Sync to upstream/release/641 (#1382)

### What's new

* Light update this week, mostly fast flag cleanups.

### New Solver

* Rename flag to enable new solver from
`DebugLuauDeferredConstraintResolution` to `LuauSolverV2`
* Added support for magic functions for the new type checker (as opposed
to the type inference component)
* Improved handling of `string.format` with magic function improvements
* Cleaning up some of the reported errors by the new type checker
* Minor refactoring of `TypeChecker2.cpp` that happens to make the diff
very hard to read.

---

### Internal Contributors

Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>

---------

Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Junseo Yoo <jyoo@roblox.com>

Analysis/include/Luau/BuiltinDefinitions.h

@@ -13,6 +13,7 @@ struct Frontend;
 struct GlobalTypes;
 struct TypeChecker;
 struct TypeArena;
+struct Subtyping;
 
 void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeCheckForAutocomplete = false);
 TypeId makeUnion(TypeArena& arena, std::vector<TypeId>&& types);
@@ -65,7 +66,7 @@ TypeId makeFunction( // Polymorphic
 void attachMagicFunction(TypeId ty, MagicFunction fn);
 void attachDcrMagicFunction(TypeId ty, DcrMagicFunction fn);
 void attachDcrMagicRefinement(TypeId ty, DcrMagicRefinement fn);
-
+void attachDcrMagicFunctionTypeCheck(TypeId ty, DcrMagicFunctionTypeCheck fn);
 Property makeProperty(TypeId ty, std::optional<std::string> documentationSymbol = std::nullopt);
 void assignPropDocumentationSymbols(TableType::Props& props, const std::string& baseName);
 

Analysis/include/Luau/Set.h

@@ -4,7 +4,7 @@
 #include "Luau/Common.h"
 #include "Luau/DenseHash.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
 {

Analysis/include/Luau/Type.h

@@ -34,6 +34,8 @@ using ScopePtr = std::shared_ptr<Scope>;
 
 struct TypeFunction;
 struct Constraint;
+struct Subtyping;
+struct TypeChecker2;
 
 /**
  * There are three kinds of type variables:
@@ -289,7 +291,6 @@ struct MagicFunctionCallContext
 };
 
 using DcrMagicFunction = std::function<bool(MagicFunctionCallContext)>;
-
 struct MagicRefinementContext
 {
     NotNull<Scope> scope;
@@ -297,8 +298,17 @@ struct MagicRefinementContext
     std::vector<std::optional<TypeId>> discriminantTypes;
 };
 
-using DcrMagicRefinement = void (*)(const MagicRefinementContext&);
+struct MagicFunctionTypeCheckContext
+{
+    NotNull<TypeChecker2> typechecker;
+    NotNull<BuiltinTypes> builtinTypes;
+    const class AstExprCall* callSite;
+    TypePackId arguments;
+    NotNull<Scope> checkScope;
+};
 
+using DcrMagicRefinement = void (*)(const MagicRefinementContext&);
+using DcrMagicFunctionTypeCheck = std::function<void(const MagicFunctionTypeCheckContext&)>;
 struct FunctionType
 {
     // Global monomorphic function
@@ -359,6 +369,14 @@ struct FunctionType
     MagicFunction magicFunction = nullptr;
     DcrMagicFunction dcrMagicFunction = nullptr;
     DcrMagicRefinement dcrMagicRefinement = nullptr;
+
+    // Callback to allow custom typechecking of builtin function calls whose argument types
+    // will only be resolved after constraint solving. For example, the arguments to string.format
+    // have types that can only be decided after parsing the format string and unifying
+    // with the passed in values, but the correctness of the call can only be decided after
+    // all the types have been finalized.
+    DcrMagicFunctionTypeCheck dcrMagicTypeCheck = nullptr;
+
     bool hasSelf;
     // `hasNoFreeOrGenericTypes` should be true if and only if the type does not have any free or generic types present inside it.
     // this flag is used as an optimization to exit early from procedures that manipulate free or generic types.

Analysis/include/Luau/TypeChecker2.h

@@ -2,7 +2,15 @@
 
 #pragma once
 
+#include "Luau/Error.h"
 #include "Luau/NotNull.h"
+#include "Luau/Common.h"
+#include "Luau/TypeUtils.h"
+#include "Luau/Type.h"
+#include "Luau/TypeFwd.h"
+#include "Luau/TypeOrPack.h"
+#include "Luau/Normalize.h"
+#include "Luau/Subtyping.h"
 
 namespace Luau
 {
@@ -13,6 +21,42 @@ struct TypeCheckLimits;
 struct UnifierSharedState;
 struct SourceModule;
 struct Module;
+struct InternalErrorReporter;
+struct Scope;
+struct PropertyType;
+struct PropertyTypes;
+struct StackPusher;
+
+struct Reasonings
+{
+    // the list of reasons
+    std::vector<std::string> reasons;
+
+    // this should be true if _all_ of the reasons have an error suppressing type, and false otherwise.
+    bool suppressed;
+
+    std::string toString()
+    {
+        // DenseHashSet ordering is entirely undefined, so we want to
+        // sort the reasons here to achieve a stable error
+        // stringification.
+        std::sort(reasons.begin(), reasons.end());
+        std::string allReasons;
+        bool first = true;
+        for (const std::string& reason : reasons)
+        {
+            if (first)
+                first = false;
+            else
+                allReasons += "\n\t";
+
+            allReasons += reason;
+        }
+
+        return allReasons;
+    }
+};
+
 
 void check(
     NotNull<BuiltinTypes> builtinTypes,
@@ -23,4 +67,154 @@ void check(
     Module* module
 );
 
+struct TypeChecker2
+{
+    NotNull<BuiltinTypes> builtinTypes;
+    DcrLogger* logger;
+    const NotNull<TypeCheckLimits> limits;
+    const NotNull<InternalErrorReporter> ice;
+    const SourceModule* sourceModule;
+    Module* module;
+
+    TypeContext typeContext = TypeContext::Default;
+    std::vector<NotNull<Scope>> stack;
+    std::vector<TypeId> functionDeclStack;
+
+    DenseHashSet<TypeId> seenTypeFunctionInstances{nullptr};
+
+    Normalizer normalizer;
+    Subtyping _subtyping;
+    NotNull<Subtyping> subtyping;
+
+    TypeChecker2(
+        NotNull<BuiltinTypes> builtinTypes,
+        NotNull<UnifierSharedState> unifierState,
+        NotNull<TypeCheckLimits> limits,
+        DcrLogger* logger,
+        const SourceModule* sourceModule,
+        Module* module
+    );
+
+    void visit(AstStatBlock* block);
+    void reportError(TypeErrorData data, const Location& location);
+    Reasonings explainReasonings(TypeId subTy, TypeId superTy, Location location, const SubtypingResult& r);
+    Reasonings explainReasonings(TypePackId subTp, TypePackId superTp, Location location, const SubtypingResult& r);
+
+private:
+    static bool allowsNoReturnValues(const TypePackId tp);
+    static Location getEndLocation(const AstExprFunction* function);
+    bool isErrorCall(const AstExprCall* call);
+    bool hasBreak(AstStat* node);
+    const AstStat* getFallthrough(const AstStat* node);
+    std::optional<StackPusher> pushStack(AstNode* node);
+    void checkForInternalTypeFunction(TypeId ty, Location location);
+    TypeId checkForTypeFunctionInhabitance(TypeId instance, Location location);
+    TypePackId lookupPack(AstExpr* expr);
+    TypeId lookupType(AstExpr* expr);
+    TypeId lookupAnnotation(AstType* annotation);
+    std::optional<TypePackId> lookupPackAnnotation(AstTypePack* annotation);
+    TypeId lookupExpectedType(AstExpr* expr);
+    TypePackId lookupExpectedPack(AstExpr* expr, TypeArena& arena);
+    TypePackId reconstructPack(AstArray<AstExpr*> exprs, TypeArena& arena);
+    Scope* findInnermostScope(Location location);
+    void visit(AstStat* stat);
+    void visit(AstStatIf* ifStatement);
+    void visit(AstStatWhile* whileStatement);
+    void visit(AstStatRepeat* repeatStatement);
+    void visit(AstStatBreak*);
+    void visit(AstStatContinue*);
+    void visit(AstStatReturn* ret);
+    void visit(AstStatExpr* expr);
+    void visit(AstStatLocal* local);
+    void visit(AstStatFor* forStatement);
+    void visit(AstStatForIn* forInStatement);
+    std::optional<TypeId> getBindingType(AstExpr* expr);
+    void reportErrorsFromAssigningToNever(AstExpr* lhs, TypeId rhsType);
+    void visit(AstStatAssign* assign);
+    void visit(AstStatCompoundAssign* stat);
+    void visit(AstStatFunction* stat);
+    void visit(AstStatLocalFunction* stat);
+    void visit(const AstTypeList* typeList);
+    void visit(AstStatTypeAlias* stat);
+    void visit(AstStatTypeFunction* stat);
+    void visit(AstTypeList types);
+    void visit(AstStatDeclareFunction* stat);
+    void visit(AstStatDeclareGlobal* stat);
+    void visit(AstStatDeclareClass* stat);
+    void visit(AstStatError* stat);
+    void visit(AstExpr* expr, ValueContext context);
+    void visit(AstExprGroup* expr, ValueContext context);
+    void visit(AstExprConstantNil* expr);
+    void visit(AstExprConstantBool* expr);
+    void visit(AstExprConstantNumber* expr);
+    void visit(AstExprConstantString* expr);
+    void visit(AstExprLocal* expr);
+    void visit(AstExprGlobal* expr);
+    void visit(AstExprVarargs* expr);
+    void visitCall(AstExprCall* call);
+    void visit(AstExprCall* call);
+    std::optional<TypeId> tryStripUnionFromNil(TypeId ty);
+    TypeId stripFromNilAndReport(TypeId ty, const Location& location);
+    void visitExprName(AstExpr* expr, Location location, const std::string& propName, ValueContext context, TypeId astIndexExprTy);
+    void visit(AstExprIndexName* indexName, ValueContext context);
+    void indexExprMetatableHelper(AstExprIndexExpr* indexExpr, const MetatableType* metaTable, TypeId exprType, TypeId indexType);
+    void visit(AstExprIndexExpr* indexExpr, ValueContext context);
+    void visit(AstExprFunction* fn);
+    void visit(AstExprTable* expr);
+    void visit(AstExprUnary* expr);
+    TypeId visit(AstExprBinary* expr, AstNode* overrideKey = nullptr);
+    void visit(AstExprTypeAssertion* expr);
+    void visit(AstExprIfElse* expr);
+    void visit(AstExprInterpString* interpString);
+    void visit(AstExprError* expr);
+    TypeId flattenPack(TypePackId pack);
+    void visitGenerics(AstArray<AstGenericType> generics, AstArray<AstGenericTypePack> genericPacks);
+    void visit(AstType* ty);
+    void visit(AstTypeReference* ty);
+    void visit(AstTypeTable* table);
+    void visit(AstTypeFunction* ty);
+    void visit(AstTypeTypeof* ty);
+    void visit(AstTypeUnion* ty);
+    void visit(AstTypeIntersection* ty);
+    void visit(AstTypePack* pack);
+    void visit(AstTypePackExplicit* tp);
+    void visit(AstTypePackVariadic* tp);
+    void visit(AstTypePackGeneric* tp);
+
+    template<typename TID>
+    Reasonings explainReasonings_(TID subTy, TID superTy, Location location, const SubtypingResult& r);
+
+    void explainError(TypeId subTy, TypeId superTy, Location location, const SubtypingResult& result);
+    void explainError(TypePackId subTy, TypePackId superTy, Location location, const SubtypingResult& result);
+    bool testIsSubtype(TypeId subTy, TypeId superTy, Location location);
+    bool testIsSubtype(TypePackId subTy, TypePackId superTy, Location location);
+    void reportError(TypeError e);
+    void reportErrors(ErrorVec errors);
+    PropertyTypes lookupProp(
+        const NormalizedType* norm,
+        const std::string& prop,
+        ValueContext context,
+        const Location& location,
+        TypeId astIndexExprType,
+        std::vector<TypeError>& errors
+    );
+    // If the provided type does not have the named property, report an error.
+    void checkIndexTypeFromType(TypeId tableTy, const std::string& prop, ValueContext context, const Location& location, TypeId astIndexExprType);
+    PropertyType hasIndexTypeFromType(
+        TypeId ty,
+        const std::string& prop,
+        ValueContext context,
+        const Location& location,
+        DenseHashSet<TypeId>& seen,
+        TypeId astIndexExprType,
+        std::vector<TypeError>& errors
+    );
+
+    void diagnoseMissingTableKey(UnknownProperty* utk, TypeErrorData& data) const;
+    bool isErrorSuppressing(Location loc, TypeId ty);
+    bool isErrorSuppressing(Location loc1, TypeId ty1, Location loc2, TypeId ty2);
+    bool isErrorSuppressing(Location loc, TypePackId tp);
+    bool isErrorSuppressing(Location loc1, TypePackId tp1, Location loc2, TypePackId tp2);
+};
+
 } // namespace Luau

Analysis/include/Luau/VisitType.h

@@ -11,7 +11,7 @@
 
 LUAU_FASTINT(LuauVisitRecursionLimit)
 LUAU_FASTFLAG(LuauBoundLazyTypes2)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
 {
@@ -226,12 +226,12 @@ struct GenericTypeVisitor
         }
         else if (auto ftv = get<FreeType>(ty))
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (visit(ty, *ftv))
                 {
                     // TODO: Replace these if statements with assert()s when we
-                    // delete FFlag::DebugLuauDeferredConstraintResolution.
+                    // delete FFlag::LuauSolverV2.
                     //
                     // When the old solver is used, these pointers are always
                     // unused. When the new solver is used, they are never null.
@@ -276,7 +276,7 @@ struct GenericTypeVisitor
                 {
                     for (auto& [_name, prop] : ttv->props)
                     {
-                        if (FFlag::DebugLuauDeferredConstraintResolution)
+                        if (FFlag::LuauSolverV2)
                         {
                             if (auto ty = prop.readTy)
                                 traverse(*ty);
@@ -314,7 +314,7 @@ struct GenericTypeVisitor
             {
                 for (const auto& [name, prop] : ctv->props)
                 {
-                    if (FFlag::DebugLuauDeferredConstraintResolution)
+                    if (FFlag::LuauSolverV2)
                     {
                         if (auto ty = prop.readTy)
                             traverse(*ty);

Analysis/src/AnyTypeSummary.cpp

@@ -692,7 +692,7 @@ bool AnyTypeSummary::containsAny(TypeId typ)
     {
         for (auto& [_name, prop] : ty->props)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (auto newT = follow(prop.readTy))
                 {

Analysis/src/AstQuery.cpp

@@ -11,8 +11,7 @@
 
 #include <algorithm>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2)
-LUAU_FASTFLAGVARIABLE(LuauFixBindingForGlobalPos, false);
 
 namespace Luau
 {
@@ -327,7 +326,7 @@ static std::optional<AstStatLocal*> findBindingLocalStatement(const SourceModule
 {
     // Bindings coming from global sources (e.g., definition files) have a zero position.
     // They cannot be defined from a local statement
-    if (FFlag::LuauFixBindingForGlobalPos && binding.location == Location{{0, 0}, {0, 0}})
+    if (binding.location == Location{{0, 0}, {0, 0}})
         return std::nullopt;
 
     std::vector<AstNode*> nodes = findAstAncestryOfPosition(source, binding.location.begin);
@@ -531,7 +530,7 @@ std::optional<DocumentationSymbol> getDocumentationSymbolAtPosition(const Source
                 {
                     if (auto propIt = ttv->props.find(indexName->index.value); propIt != ttv->props.end())
                     {
-                        if (FFlag::DebugLuauDeferredConstraintResolution)
+                        if (FFlag::LuauSolverV2)
                         {
                             if (auto ty = propIt->second.readTy)
                                 return checkOverloadedDocumentationSymbol(module, *ty, parentExpr, propIt->second.documentationSymbol);
@@ -544,7 +543,7 @@ std::optional<DocumentationSymbol> getDocumentationSymbolAtPosition(const Source
                 {
                     if (auto propIt = ctv->props.find(indexName->index.value); propIt != ctv->props.end())
                     {
-                        if (FFlag::DebugLuauDeferredConstraintResolution)
+                        if (FFlag::LuauSolverV2)
                         {
                             if (auto ty = propIt->second.readTy)
                                 return checkOverloadedDocumentationSymbol(module, *ty, parentExpr, propIt->second.documentationSymbol);

Analysis/src/Autocomplete.cpp

@@ -13,7 +13,7 @@
 #include <unordered_set>
 #include <utility>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 static const std::unordered_set<std::string> kStatementStartingKeywords =
     {"while", "if", "local", "repeat", "function", "do", "for", "return", "break", "continue", "type", "export"};
@@ -142,7 +142,7 @@ static bool checkTypeMatch(TypeId subTy, TypeId superTy, NotNull<Scope> scope, T
     UnifierSharedState unifierState(&iceReporter);
     Normalizer normalizer{typeArena, builtinTypes, NotNull{&unifierState}};
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         Subtyping subtyping{builtinTypes, NotNull{typeArena}, NotNull{&normalizer}, NotNull{&iceReporter}};
 
@@ -293,7 +293,7 @@ static void autocompleteProps(
             {
                 Luau::TypeId type;
 
-                if (FFlag::DebugLuauDeferredConstraintResolution)
+                if (FFlag::LuauSolverV2)
                 {
                     if (auto ty = prop.readTy)
                         type = follow(*ty);
@@ -1964,7 +1964,7 @@ AutocompleteResult autocomplete(Frontend& frontend, const ModuleName& moduleName
         return {};
 
     ModulePtr module;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         module = frontend.moduleResolver.getModule(moduleName);
     else
         module = frontend.moduleResolverForAutocomplete.getModule(moduleName);
@@ -1974,7 +1974,7 @@ AutocompleteResult autocomplete(Frontend& frontend, const ModuleName& moduleName
 
     NotNull<BuiltinTypes> builtinTypes = frontend.builtinTypes;
     Scope* globalScope;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         globalScope = frontend.globals.globalScope.get();
     else
         globalScope = frontend.globalsForAutocomplete.globalScope.get();

Analysis/src/BuiltinDefinitions.cpp

@@ -10,10 +10,12 @@
 #include "Luau/ConstraintGenerator.h"
 #include "Luau/NotNull.h"
 #include "Luau/TypeInfer.h"
+#include "Luau/TypeChecker2.h"
 #include "Luau/TypeFunction.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
 #include "Luau/TypeUtils.h"
+#include "Luau/Subtyping.h"
 
 #include <algorithm>
 
@@ -23,7 +25,8 @@
  * about a function that takes any number of values, but where each value must have some specific type.
  */
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
+LUAU_FASTFLAGVARIABLE(LuauDCRMagicFunctionTypeChecker, false);
 
 namespace Luau
 {
@@ -181,6 +184,14 @@ void attachDcrMagicRefinement(TypeId ty, DcrMagicRefinement fn)
         LUAU_ASSERT(!"Got a non functional type");
 }
 
+void attachDcrMagicFunctionTypeCheck(TypeId ty, DcrMagicFunctionTypeCheck fn)
+{
+    if (auto ftv = getMutable<FunctionType>(ty))
+        ftv->dcrMagicTypeCheck = fn;
+    else
+        LUAU_ASSERT(!"Got a non functional type");
+}
+
 Property makeProperty(TypeId ty, std::optional<std::string> documentationSymbol)
 {
     return {
@@ -260,7 +271,7 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
     TypeArena& arena = globals.globalTypes;
     NotNull<BuiltinTypes> builtinTypes = globals.builtinTypes;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         builtinTypeFunctions().addToScope(NotNull{&arena}, NotNull{globals.globalScope.get()});
 
     LoadDefinitionFileResult loadResult = frontend.loadDefinitionFile(
@@ -305,7 +316,7 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
     // getmetatable : <MT>({ @metatable MT, {+ +} }) -> MT
     addGlobalBinding(globals, "getmetatable", makeFunction(arena, std::nullopt, {genericMT}, {}, {tableMetaMT}, {genericMT}), "@luau");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         TypeId genericT = arena.addType(GenericType{"T"});
         TypeId tMetaMT = arena.addType(MetatableType{genericT, genericMT});
@@ -354,7 +365,7 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
 
     attachMagicFunction(getGlobalBinding(globals, "assert"), magicFunctionAssert);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // declare function assert<T>(value: T, errorMessage: string?): intersect<T, ~(false?)>
         TypeId genericT = arena.addType(GenericType{"T"});
@@ -374,7 +385,7 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
 
     if (TableType* ttv = getMutable<TableType>(getGlobalBinding(globals, "table")))
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             // CLI-114044 - The new solver does not yet support generic tables,
             // which act, in an odd way, like generics that are constrained to
@@ -517,7 +528,7 @@ static bool dcrMagicFunctionFormat(MagicFunctionCallContext context)
 
     size_t paramOffset = 1;
 
-    // unify the prefix one argument at a time
+    // unify the prefix one argument at a time - needed if any of the involved types are free
     for (size_t i = 0; i < expected.size() && i + paramOffset < params.size(); ++i)
     {
         context.solver->unify(context.constraint, params[i + paramOffset], expected[i]);
@@ -530,12 +541,52 @@ static bool dcrMagicFunctionFormat(MagicFunctionCallContext context)
     if (numExpectedParams != numActualParams && (!tail || numExpectedParams < numActualParams))
         context.solver->reportError(TypeError{context.callSite->location, CountMismatch{numExpectedParams, std::nullopt, numActualParams}});
 
+    // This is invoked at solve time, so we just need to provide a type for the result of :/.format
     TypePackId resultPack = arena->addTypePack({context.solver->builtinTypes->stringType});
     asMutable(context.result)->ty.emplace<BoundTypePack>(resultPack);
 
     return true;
 }
 
+static void dcrMagicFunctionTypeCheckFormat(MagicFunctionTypeCheckContext context)
+{
+    AstExprConstantString* fmt = nullptr;
+    if (auto index = context.callSite->func->as<AstExprIndexName>(); index && context.callSite->self)
+    {
+        if (auto group = index->expr->as<AstExprGroup>())
+            fmt = group->expr->as<AstExprConstantString>();
+        else
+            fmt = index->expr->as<AstExprConstantString>();
+    }
+
+    if (!context.callSite->self && context.callSite->args.size > 0)
+        fmt = context.callSite->args.data[0]->as<AstExprConstantString>();
+
+    if (!fmt)
+        return;
+
+    std::vector<TypeId> expected = parseFormatString(context.builtinTypes, fmt->value.data, fmt->value.size);
+    const auto& [params, tail] = flatten(context.arguments);
+
+    size_t paramOffset = 1;
+    // Compare the expressions passed with the types the function expects to determine whether this function was called with : or .
+    bool calledWithSelf = expected.size() == context.callSite->args.size;
+    // unify the prefix one argument at a time
+    for (size_t i = 0; i < expected.size() && i + paramOffset < params.size(); ++i)
+    {
+        TypeId actualTy = params[i + paramOffset];
+        TypeId expectedTy = expected[i];
+        Location location = context.callSite->args.data[i + (calledWithSelf ? 0 : paramOffset)]->location;
+        // use subtyping instead here
+        SubtypingResult result = context.typechecker->subtyping->isSubtype(actualTy, expectedTy, context.checkScope);
+        if (!result.isSubtype)
+        {
+            Reasonings reasonings = context.typechecker->explainReasonings(actualTy, expectedTy, location, result);
+            context.typechecker->reportError(TypeMismatch{expectedTy, actualTy, reasonings.toString()}, location);
+        }
+    }
+}
+
 static std::vector<TypeId> parsePatternString(NotNull<BuiltinTypes> builtinTypes, const char* data, size_t size)
 {
     std::vector<TypeId> result;
@@ -869,7 +920,7 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
     const TypePackId oneStringPack = arena->addTypePack({stringType});
     const TypePackId anyTypePack = builtinTypes->anyTypePack;
 
-    const TypePackId variadicTailPack = FFlag::DebugLuauDeferredConstraintResolution ? builtinTypes->unknownTypePack : anyTypePack;
+    const TypePackId variadicTailPack = FFlag::LuauSolverV2 ? builtinTypes->unknownTypePack : anyTypePack;
     const TypePackId emptyPack = arena->addTypePack({});
     const TypePackId stringVariadicList = arena->addTypePack(TypePackVar{VariadicTypePack{stringType}});
     const TypePackId numberVariadicList = arena->addTypePack(TypePackVar{VariadicTypePack{numberType}});
@@ -880,6 +931,8 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
     formatFTV.isCheckedFunction = true;
     const TypeId formatFn = arena->addType(formatFTV);
     attachDcrMagicFunction(formatFn, dcrMagicFunctionFormat);
+    if (FFlag::LuauDCRMagicFunctionTypeChecker)
+        attachDcrMagicFunctionTypeCheck(formatFn, dcrMagicFunctionTypeCheckFormat);
 
 
     const TypeId stringToStringType = makeFunction(*arena, std::nullopt, {}, {}, {stringType}, {}, {stringType}, /* checked */ true);

Analysis/src/Clone.cpp

@@ -6,7 +6,7 @@
 #include "Luau/TypePack.h"
 #include "Luau/Unifiable.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 // For each `Luau::clone` call, we will clone only up to N amount of types _and_ packs, as controlled by this limit.
 LUAU_FASTINTVARIABLE(LuauTypeCloneIterationLimit, 100'000)
@@ -191,7 +191,7 @@ private:
 
     Property shallowClone(const Property& p)
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             std::optional<TypeId> cloneReadTy;
             if (auto ty = p.readTy)

Analysis/src/DataFlowGraph.cpp

@@ -10,7 +10,7 @@
 #include <optional>
 
 LUAU_FASTFLAG(DebugLuauFreezeArena)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
 {
@@ -139,7 +139,7 @@ DataFlowGraph DataFlowGraphBuilder::build(AstStatBlock* block, NotNull<InternalE
 {
     LUAU_TIMETRACE_SCOPE("DataFlowGraphBuilder::build", "Typechecking");
 
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
 
     DataFlowGraphBuilder builder;
     builder.handle = handle;

Analysis/src/Frontend.cpp

@@ -38,7 +38,7 @@ LUAU_FASTINT(LuauTarjanChildLimit)
 LUAU_FASTFLAG(LuauInferInNoCheckMode)
 LUAU_FASTFLAGVARIABLE(LuauKnowsTheDataModel3, false)
 LUAU_FASTFLAGVARIABLE(LuauStoreCommentsForDefinitionFiles, false)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverToJson, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverToJsonFile, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauForbidInternalTypes, false)
@@ -473,7 +473,7 @@ CheckResult Frontend::check(const ModuleName& name, std::optional<FrontendOption
     LUAU_TIMETRACE_ARGUMENT("name", name.c_str());
 
     FrontendOptions frontendOptions = optionOverride.value_or(options);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         frontendOptions.forAutocomplete = false;
 
     if (std::optional<CheckResult> result = getCheckResult(name, true, frontendOptions.forAutocomplete))
@@ -547,7 +547,7 @@ std::vector<ModuleName> Frontend::checkQueuedModules(
 )
 {
     FrontendOptions frontendOptions = optionOverride.value_or(options);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         frontendOptions.forAutocomplete = false;
 
     // By taking data into locals, we make sure queue is cleared at the end, even if an ICE or a different exception is thrown
@@ -781,7 +781,7 @@ std::vector<ModuleName> Frontend::checkQueuedModules(
 
 std::optional<CheckResult> Frontend::getCheckResult(const ModuleName& name, bool accumulateNested, bool forAutocomplete)
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         forAutocomplete = false;
 
     auto it = sourceNodes.find(name);
@@ -1064,7 +1064,7 @@ void Frontend::checkBuildQueueItem(BuildQueueItem& item)
     if (DFFlag::LuauRunCustomModuleChecks && item.options.customModuleCheck)
         item.options.customModuleCheck(sourceModule, *module);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution && mode == Mode::NoCheck)
+    if (FFlag::LuauSolverV2 && mode == Mode::NoCheck)
         module->errors.clear();
 
     if (item.options.runLintChecks)
@@ -1531,7 +1531,7 @@ ModulePtr Frontend::check(
     TypeCheckLimits typeCheckLimits
 )
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         auto prepareModuleScopeWrap = [this, forAutocomplete](const ModuleName& name, const ScopePtr& scope)
         {

Analysis/src/Instantiation.cpp

@@ -10,7 +10,7 @@
 
 #include <algorithm>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
 {
@@ -157,7 +157,7 @@ TypeId ReplaceGenerics::clean(TypeId ty)
         clone.definitionLocation = ttv->definitionLocation;
         return addType(std::move(clone));
     }
-    else if (FFlag::DebugLuauDeferredConstraintResolution)
+    else if (FFlag::LuauSolverV2)
     {
         TypeId res = freshType(NotNull{arena}, builtinTypes, scope);
         getMutable<FreeType>(res)->level = level;

Analysis/src/Linter.cpp

@@ -14,7 +14,7 @@
 
 LUAU_FASTINTVARIABLE(LuauSuggestionDistance, 4)
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 LUAU_FASTFLAG(LuauAttribute)
 LUAU_FASTFLAG(LuauNativeAttribute)
@@ -1971,7 +1971,7 @@ private:
 
     bool visit(AstTypeTable* node) override
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             struct Rec
             {

Analysis/src/Module.cpp

@@ -14,7 +14,7 @@
 
 #include <algorithm>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAGVARIABLE(LuauSkipEmptyInstantiations, false);
 
 namespace Luau
@@ -220,7 +220,7 @@ void Module::clonePublicInterface(NotNull<BuiltinTypes> builtinTypes, InternalEr
     ScopePtr moduleScope = getModuleScope();
 
     TypePackId returnType = moduleScope->returnType;
-    std::optional<TypePackId> varargPack = FFlag::DebugLuauDeferredConstraintResolution ? std::nullopt : moduleScope->varargPack;
+    std::optional<TypePackId> varargPack = FFlag::LuauSolverV2 ? std::nullopt : moduleScope->varargPack;
 
     TxnLog log;
     ClonePublicInterface clonePublicInterface{&log, builtinTypes, this};

Analysis/src/Normalize.cpp

@@ -24,16 +24,16 @@ LUAU_FASTFLAGVARIABLE(LuauFixCyclicTablesBlowingStack, false);
 // This could theoretically be 2000 on amd64, but x86 requires this.
 LUAU_FASTINTVARIABLE(LuauNormalizeIterationLimit, 1200);
 LUAU_FASTINTVARIABLE(LuauNormalizeCacheLimit, 100000);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 static bool fixReduceStackPressure()
 {
-    return FFlag::LuauFixReduceStackPressure || FFlag::DebugLuauDeferredConstraintResolution;
+    return FFlag::LuauFixReduceStackPressure || FFlag::LuauSolverV2;
 }
 
 static bool fixCyclicTablesBlowingStack()
 {
-    return FFlag::LuauFixCyclicTablesBlowingStack || FFlag::DebugLuauDeferredConstraintResolution;
+    return FFlag::LuauFixCyclicTablesBlowingStack || FFlag::LuauSolverV2;
 }
 
 namespace Luau
@@ -42,7 +42,7 @@ namespace Luau
 // helper to make `FFlag::LuauNormalizeAwayUninhabitableTables` not explicitly required when DCR is enabled.
 static bool normalizeAwayUninhabitableTables()
 {
-    return FFlag::LuauNormalizeAwayUninhabitableTables || FFlag::DebugLuauDeferredConstraintResolution;
+    return FFlag::LuauNormalizeAwayUninhabitableTables || FFlag::LuauSolverV2;
 }
 
 static bool shouldEarlyExit(NormalizationResult res)
@@ -553,7 +553,7 @@ NormalizationResult Normalizer::isInhabited(TypeId ty, Set<TypeId>& seen)
     {
         for (const auto& [_, prop] : ttv->props)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 // A table enclosing a read property whose type is uninhabitable is also itself uninhabitable,
                 // but not its write property. That just means the write property doesn't exist, and so is readonly.
@@ -2583,7 +2583,7 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
         {
             const auto& [_name, tprop] = *tfound;
             // TODO: variance issues here, which can't be fixed until we have read/write property types
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (hprop.readTy.has_value())
                 {
@@ -3249,7 +3249,7 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
             // this is a noop since an intersection with `unknown` is trivial.
             return NormalizationResult::True;
         }
-        else if ((FFlag::LuauNormalizeNotUnknownIntersection || FFlag::DebugLuauDeferredConstraintResolution) && get<UnknownType>(t))
+        else if ((FFlag::LuauNormalizeNotUnknownIntersection || FFlag::LuauSolverV2) && get<UnknownType>(t))
         {
             // if we're intersecting with `~unknown`, this is equivalent to intersecting with `never`
             // this means we should clear the type entirely.
@@ -3389,7 +3389,7 @@ TypeId Normalizer::typeFromNormal(const NormalizedType& norm)
     if (!get<NeverType>(norm.buffers))
         result.push_back(builtinTypes->bufferType);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         result.reserve(result.size() + norm.tables.size());
         for (auto table : norm.tables)
@@ -3427,7 +3427,7 @@ bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<Built
     Normalizer normalizer{&arena, builtinTypes, NotNull{&sharedState}};
 
     // Subtyping under DCR is not implemented using unification!
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         Subtyping subtyping{builtinTypes, NotNull{&arena}, NotNull{&normalizer}, NotNull{&ice}};
 
@@ -3449,7 +3449,7 @@ bool isSubtype(TypePackId subPack, TypePackId superPack, NotNull<Scope> scope, N
     Normalizer normalizer{&arena, builtinTypes, NotNull{&sharedState}};
 
     // Subtyping under DCR is not implemented using unification!
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         Subtyping subtyping{builtinTypes, NotNull{&arena}, NotNull{&normalizer}, NotNull{&ice}};
 
@@ -3466,7 +3466,7 @@ bool isSubtype(TypePackId subPack, TypePackId superPack, NotNull<Scope> scope, N
 
 bool isConsistentSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice)
 {
-    LUAU_ASSERT(!FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(!FFlag::LuauSolverV2);
 
     UnifierSharedState sharedState{&ice};
     TypeArena arena;
@@ -3486,7 +3486,7 @@ bool isConsistentSubtype(
     InternalErrorReporter& ice
 )
 {
-    LUAU_ASSERT(!FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(!FFlag::LuauSolverV2);
 
     UnifierSharedState sharedState{&ice};
     TypeArena arena;

Analysis/src/Scope.cpp

@@ -2,7 +2,7 @@
 
 #include "Luau/Scope.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 namespace Luau
 {
@@ -184,7 +184,7 @@ std::optional<Binding> Scope::linearSearchForBinding(const std::string& name, bo
 // Updates the `this` scope with the assignments from the `childScope` including ones that doesn't exist in `this`.
 void Scope::inheritAssignments(const ScopePtr& childScope)
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     for (const auto& [k, a] : childScope->lvalueTypes)
@@ -194,7 +194,7 @@ void Scope::inheritAssignments(const ScopePtr& childScope)
 // Updates the `this` scope with the refinements from the `childScope` excluding ones that doesn't exist in `this`.
 void Scope::inheritRefinements(const ScopePtr& childScope)
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         for (const auto& [k, a] : childScope->rvalueRefinements)
         {

Analysis/src/Simplify.cpp

@@ -12,7 +12,7 @@
 #include <algorithm>
 
 LUAU_FASTINT(LuauTypeReductionRecursionLimit)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_DYNAMIC_FASTINTVARIABLE(LuauSimplificationComplexityLimit, 8);
 
 namespace Luau
@@ -1398,7 +1398,7 @@ TypeId TypeSimplifier::simplify(TypeId ty, DenseHashSet<TypeId>& seen)
 
 SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
 
     TypeSimplifier s{builtinTypes, arena};
 
@@ -1413,7 +1413,7 @@ SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<
 
 SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, std::set<TypeId> parts)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
 
     TypeSimplifier s{builtinTypes, arena};
 
@@ -1424,7 +1424,7 @@ SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<
 
 SimplifyResult simplifyUnion(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
 
     TypeSimplifier s{builtinTypes, arena};
 

Analysis/src/Substitution.cpp

@@ -9,7 +9,7 @@
 #include <stdexcept>
 
 LUAU_FASTINTVARIABLE(LuauTarjanChildLimit, 10000)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTINTVARIABLE(LuauTarjanPreallocationSize, 256);
 
 namespace Luau
@@ -182,7 +182,7 @@ void Tarjan::visitChildren(TypeId ty, int index)
         LUAU_ASSERT(!ttv->boundTo);
         for (const auto& [name, prop] : ttv->props)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 visitChild(prop.readTy);
                 visitChild(prop.writeTy);
@@ -740,7 +740,7 @@ void Substitution::replaceChildren(TypeId ty)
         LUAU_ASSERT(!ttv->boundTo);
         for (auto& [name, prop] : ttv->props)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (prop.readTy)
                     prop.readTy = replace(prop.readTy);

Analysis/src/Symbol.cpp

@@ -3,7 +3,7 @@
 
 #include "Luau/Common.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
 {
@@ -14,7 +14,7 @@ bool Symbol::operator==(const Symbol& rhs) const
         return local == rhs.local;
     else if (global.value)
         return rhs.global.value && global == rhs.global.value; // Subtlety: AstName::operator==(const char*) uses strcmp, not pointer identity.
-    else if (FFlag::DebugLuauDeferredConstraintResolution)
+    else if (FFlag::LuauSolverV2)
         return !rhs.local && !rhs.global.value; // Reflexivity: we already know `this` Symbol is empty, so check that rhs is.
     else
         return false;

Analysis/src/ToDot.cpp

@@ -10,7 +10,7 @@
 #include <unordered_map>
 #include <unordered_set>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 namespace Luau
 {
@@ -254,7 +254,7 @@ void StateDot::visitChildren(TypeId ty, int index)
             finishNodeLabel(ty);
             finishNode();
 
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (!get<NeverType>(t.lowerBound))
                     visitChild(t.lowerBound, index, "[lowerBound]");

Analysis/src/ToString.cpp

@@ -19,7 +19,7 @@
 #include <stdexcept>
 #include <string>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 /*
  * Enables increasing levels of verbosity for Luau type names when stringifying.
@@ -83,10 +83,10 @@ struct FindCyclicTypes final : TypeVisitor
         if (!visited.insert(ty))
             return false;
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             // TODO: Replace these if statements with assert()s when we
-            // delete FFlag::DebugLuauDeferredConstraintResolution.
+            // delete FFlag::LuauSolverV2.
             //
             // When the old solver is used, these pointers are always
             // unused. When the new solver is used, they are never null.
@@ -411,7 +411,7 @@ struct TypeStringifier
 
     void stringify(const std::string& name, const Property& prop)
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             return _newStringify(name, prop);
 
         emitKey(name);
@@ -473,7 +473,7 @@ struct TypeStringifier
 
         // TODO: ftv.lowerBound and ftv.upperBound should always be non-nil when
         // the new solver is used. This can be replaced with an assert.
-        if (FFlag::DebugLuauDeferredConstraintResolution && ftv.lowerBound && ftv.upperBound)
+        if (FFlag::LuauSolverV2 && ftv.lowerBound && ftv.upperBound)
         {
             const TypeId lowerBound = follow(ftv.lowerBound);
             const TypeId upperBound = follow(ftv.upperBound);
@@ -511,7 +511,7 @@ struct TypeStringifier
         if (FInt::DebugLuauVerboseTypeNames >= 2)
         {
             state.emit("-");
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 state.emitLevel(ftv.scope);
             else
                 state.emit(ftv.level);
@@ -540,7 +540,7 @@ struct TypeStringifier
         if (FInt::DebugLuauVerboseTypeNames >= 2)
         {
             state.emit("-");
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 state.emitLevel(gtv.scope);
             else
                 state.emit(gtv.level);
@@ -643,7 +643,7 @@ struct TypeStringifier
             state.emit(">");
         }
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             if (ftv.isCheckedFunction)
                 state.emit("@checked ");
@@ -726,10 +726,10 @@ struct TypeStringifier
 
         std::string openbrace = "@@@";
         std::string closedbrace = "@@@?!";
-        switch (state.opts.hideTableKind ? (FFlag::DebugLuauDeferredConstraintResolution ? TableState::Sealed : TableState::Unsealed) : ttv.state)
+        switch (state.opts.hideTableKind ? (FFlag::LuauSolverV2 ? TableState::Sealed : TableState::Unsealed) : ttv.state)
         {
         case TableState::Sealed:
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 openbrace = "{";
                 closedbrace = "}";
@@ -742,7 +742,7 @@ struct TypeStringifier
             }
             break;
         case TableState::Unsealed:
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 state.result.invalid = true;
                 openbrace = "{|";
@@ -1200,7 +1200,7 @@ struct TypePackStringifier
         if (FInt::DebugLuauVerboseTypeNames >= 2)
         {
             state.emit("-");
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 state.emitLevel(pack.scope);
             else
                 state.emit(pack.level);
@@ -1219,7 +1219,7 @@ struct TypePackStringifier
         if (FInt::DebugLuauVerboseTypeNames >= 2)
         {
             state.emit("-");
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 state.emitLevel(pack.scope);
             else
                 state.emit(pack.level);

Analysis/src/Type.cpp

@@ -752,7 +752,7 @@ TypeId Property::type() const
 void Property::setType(TypeId ty)
 {
     readTy = ty;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         writeTy = ty;
 }
 

Analysis/src/TypePack.cpp

@@ -6,7 +6,7 @@
 
 #include <stdexcept>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 namespace Luau
 {

Analysis/src/TypePath.cpp

@@ -13,7 +13,7 @@
 #include <sstream>
 #include <type_traits>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 // Maximum number of steps to follow when traversing a path. May not always
 // equate to the number of components in a path, depending on the traversal
@@ -29,7 +29,7 @@ namespace TypePath
 Property::Property(std::string name)
     : name(std::move(name))
 {
-    LUAU_ASSERT(!FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(!FFlag::LuauSolverV2);
 }
 
 Property Property::read(std::string name)
@@ -156,21 +156,21 @@ Path PathBuilder::build()
 
 PathBuilder& PathBuilder::readProp(std::string name)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
     components.push_back(Property{std::move(name), true});
     return *this;
 }
 
 PathBuilder& PathBuilder::writeProp(std::string name)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
     components.push_back(Property{std::move(name), false});
     return *this;
 }
 
 PathBuilder& PathBuilder::prop(std::string name)
 {
-    LUAU_ASSERT(!FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(!FFlag::LuauSolverV2);
     components.push_back(Property{std::move(name)});
     return *this;
 }
@@ -343,7 +343,7 @@ struct TraversalState
         if (prop)
         {
             std::optional<TypeId> maybeType;
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 maybeType = property.isRead ? prop->readTy : prop->writeTy;
             else
                 maybeType = prop->type();
@@ -540,7 +540,7 @@ std::string toString(const TypePath::Path& path, bool prefixDot)
         if constexpr (std::is_same_v<T, TypePath::Property>)
         {
             result << '[';
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 if (c.isRead)
                     result << "read ";

Analysis/src/TypeUtils.cpp

@@ -9,7 +9,7 @@
 
 #include <algorithm>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 namespace Luau
 {
@@ -153,7 +153,7 @@ std::optional<TypeId> findTablePropertyRespectingMeta(
         const auto& it = tableType->props.find(name);
         if (it != tableType->props.end())
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 switch (context)
                 {
@@ -301,7 +301,7 @@ TypePack extendTypePack(
 
             TypePack newPack;
             newPack.tail = arena.freshTypePack(ftp->scope);
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 result.tail = newPack.tail;
             size_t overridesIndex = 0;
             while (result.head.size() < length)
@@ -313,7 +313,7 @@ TypePack extendTypePack(
                 }
                 else
                 {
-                    if (FFlag::DebugLuauDeferredConstraintResolution)
+                    if (FFlag::LuauSolverV2)
                     {
                         FreeType ft{ftp->scope, builtinTypes->neverType, builtinTypes->unknownType};
                         t = arena.addType(ft);
@@ -426,7 +426,7 @@ TypeId stripNil(NotNull<BuiltinTypes> builtinTypes, TypeArena& arena, TypeId ty)
 
 ErrorSuppression shouldSuppressErrors(NotNull<Normalizer> normalizer, TypeId ty)
 {
-    LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(FFlag::LuauSolverV2);
     std::shared_ptr<const NormalizedType> normType = normalizer->normalize(ty);
 
     if (!normType)

Analysis/src/Unifier.cpp

@@ -19,7 +19,7 @@ LUAU_FASTINT(LuauTypeInferTypePackLoopLimit)
 LUAU_FASTFLAG(LuauErrorRecoveryType)
 LUAU_FASTFLAGVARIABLE(LuauInstantiateInSubtyping, false)
 LUAU_FASTFLAGVARIABLE(LuauTransitiveSubtyping, false)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAGVARIABLE(LuauFixIndexerSubtypingOrdering, false)
 LUAU_FASTFLAGVARIABLE(LuauUnifierShouldNotCopyError, false)
 LUAU_FASTFLAGVARIABLE(LuauUnifierRecursionOnRestart, false)
@@ -405,7 +405,7 @@ Unifier::Unifier(NotNull<Normalizer> normalizer, NotNull<Scope> scope, const Loc
     LUAU_ASSERT(sharedState.iceHandler);
 
     // Unifier is not usable when this flag is enabled! Please consider using Subtyping instead.
-    LUAU_ASSERT(!FFlag::DebugLuauDeferredConstraintResolution);
+    LUAU_ASSERT(!FFlag::LuauSolverV2);
 }
 
 void Unifier::tryUnify(TypeId subTy, TypeId superTy, bool isFunctionCall, bool isIntersection, const LiteralProperties* literalProperties)
@@ -1646,7 +1646,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
 
         auto mkFreshType = [this](Scope* scope, TypeLevel level)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
                 return freshType(NotNull{types}, builtinTypes, scope);
             else
                 return types->freshType(scope, level);

Ast/src/Parser.cpp

@@ -16,7 +16,7 @@ LUAU_FASTINTVARIABLE(LuauParseErrorLimit, 100)
 // Warning: If you are introducing new syntax, ensure that it is behind a separate
 // flag so that we don't break production games by reverting syntax changes.
 // See docs/SyntaxChanges.md for an explanation.
-LUAU_FASTFLAGVARIABLE(DebugLuauDeferredConstraintResolution, false)
+LUAU_FASTFLAGVARIABLE(LuauSolverV2, false)
 LUAU_FASTFLAGVARIABLE(LuauNativeAttribute, false)
 LUAU_FASTFLAGVARIABLE(LuauAttributeSyntaxFunExpr, false)
 LUAU_FASTFLAGVARIABLE(LuauUserDefinedTypeFunctions, false)

Common/include/Luau/Bytecode.h

@@ -441,7 +441,7 @@ enum LuauBytecodeTag
     // Bytecode version; runtime supports [MIN, MAX], compiler emits TARGET by default but may emit a higher version when flags are enabled
     LBC_VERSION_MIN = 3,
     LBC_VERSION_MAX = 6,
-    LBC_VERSION_TARGET = 5,
+    LBC_VERSION_TARGET = 6,
     // Type encoding version
     LBC_TYPE_VERSION_MIN = 1,
     LBC_TYPE_VERSION_MAX = 3,

Common/include/Luau/ExperimentalFlags.h

@@ -14,6 +14,7 @@ inline bool isFlagExperimental(const char* flag)
         "LuauInstantiateInSubtyping",      // requires some fixes to lua-apps code
         "LuauFixIndexerSubtypingOrdering", // requires some small fixes to lua-apps code since this fixes a false negative
         "StudioReportLuauAny2",             // takes telemetry data for usage of any types 
+        "LuauSolverV2",
         // makes sure we always have at least one entry
         nullptr,
     };

Compiler/src/BytecodeBuilder.cpp

@@ -7,9 +7,6 @@
 #include <algorithm>
 #include <string.h>
 
-LUAU_FASTFLAG(LuauCompileUserdataInfo)
-LUAU_FASTFLAG(LuauCompileFastcall3)
-
 namespace Luau
 {
 
@@ -334,8 +331,6 @@ unsigned int BytecodeBuilder::addStringTableEntry(StringRef value)
 
 const char* BytecodeBuilder::tryGetUserdataTypeName(LuauBytecodeType type) const
 {
-    LUAU_ASSERT(FFlag::LuauCompileUserdataInfo);
-
     unsigned index = unsigned((type & ~LBC_TYPE_OPTIONAL_BIT) - LBC_TYPE_TAGGED_USERDATA_BASE);
 
     if (index < userdataTypes.size())
@@ -575,8 +570,6 @@ void BytecodeBuilder::pushUpvalTypeInfo(LuauBytecodeType type)
 
 uint32_t BytecodeBuilder::addUserdataType(const char* name)
 {
-    LUAU_ASSERT(FFlag::LuauCompileUserdataInfo);
-
     UserdataType ty;
 
     ty.name = name;
@@ -587,8 +580,6 @@ uint32_t BytecodeBuilder::addUserdataType(const char* name)
 
 void BytecodeBuilder::useUserdataType(uint32_t index)
 {
-    LUAU_ASSERT(FFlag::LuauCompileUserdataInfo);
-
     userdataTypes[index].used = true;
 }
 
@@ -673,14 +664,11 @@ void BytecodeBuilder::finalize()
 {
     LUAU_ASSERT(bytecode.empty());
 
-    if (FFlag::LuauCompileUserdataInfo)
-    {
     for (auto& ty : userdataTypes)
     {
         if (ty.used)
             ty.nameRef = addStringTableEntry(StringRef({ty.name.c_str(), ty.name.length()}));
     }
-    }
 
     // preallocate space for bytecode blob
     size_t capacity = 16;
@@ -705,7 +693,6 @@ void BytecodeBuilder::finalize()
 
     writeStringTable(bytecode);
 
-    if (FFlag::LuauCompileUserdataInfo)
     {
         // Write the mapping between used type name indices and their name
         for (uint32_t i = 0; i < uint32_t(userdataTypes.size()); i++)
@@ -1232,19 +1219,12 @@ std::string BytecodeBuilder::getError(const std::string& message)
 
 uint8_t BytecodeBuilder::getVersion()
 {
-    // This function usually returns LBC_VERSION_TARGET but may sometimes return a higher number (within LBC_VERSION_MIN/MAX) under fast flags
-    if (FFlag::LuauCompileFastcall3)
-        return 6;
-
     return LBC_VERSION_TARGET;
 }
 
 uint8_t BytecodeBuilder::getTypeEncodingVersion()
 {
-    if (FFlag::LuauCompileUserdataInfo)
     return LBC_TYPE_VERSION_TARGET;
-
-    return 2;
 }
 
 #ifdef LUAU_ASSERTENABLED
@@ -1617,8 +1597,6 @@ void BytecodeBuilder::validateInstructions() const
             break;
 
         case LOP_FASTCALL3:
-            LUAU_ASSERT(FFlag::LuauCompileFastcall3);
-
             VREG(LUAU_INSN_B(insn));
             VJUMP(LUAU_INSN_C(insn));
             LUAU_ASSERT(LUAU_INSN_OP(insns[i + 1 + LUAU_INSN_C(insn)]) == LOP_CALL);
@@ -2240,8 +2218,6 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_FASTCALL3:
-        LUAU_ASSERT(FFlag::LuauCompileFastcall3);
-
         formatAppend(result, "FASTCALL3 %d R%d R%d R%d L%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code & 0xff, (*code >> 8) & 0xff, targetLabel);
         code++;
         break;
@@ -2373,8 +2349,6 @@ std::string BytecodeBuilder::dumpCurrentFunction(std::vector<int>& dumpinstoffs)
     {
         const std::string& typeinfo = functions.back().typeinfo;
 
-        if (FFlag::LuauCompileUserdataInfo)
-        {
         // Arguments start from third byte in function typeinfo string
         for (uint8_t i = 2; i < typeinfo.size(); ++i)
         {
@@ -2409,40 +2383,6 @@ std::string BytecodeBuilder::dumpCurrentFunction(std::vector<int>& dumpinstoffs)
             formatAppend(result, "R%d: %s%s from %d to %d\n", l.reg, name, optional, l.startpc, l.endpc);
         }
     }
-        else
-        {
-            // Arguments start from third byte in function typeinfo string
-            for (uint8_t i = 2; i < typeinfo.size(); ++i)
-            {
-                uint8_t et = typeinfo[i];
-
-                const char* base = getBaseTypeString(et);
-                const char* optional = (et & LBC_TYPE_OPTIONAL_BIT) ? "?" : "";
-
-                formatAppend(result, "R%d: %s%s [argument]\n", i - 2, base, optional);
-            }
-
-            for (size_t i = 0; i < typedUpvals.size(); ++i)
-            {
-                const TypedUpval& l = typedUpvals[i];
-
-                const char* base = getBaseTypeString(l.type);
-                const char* optional = (l.type & LBC_TYPE_OPTIONAL_BIT) ? "?" : "";
-
-                formatAppend(result, "U%d: %s%s\n", int(i), base, optional);
-            }
-
-            for (size_t i = 0; i < typedLocals.size(); ++i)
-            {
-                const TypedLocal& l = typedLocals[i];
-
-                const char* base = getBaseTypeString(l.type);
-                const char* optional = (l.type & LBC_TYPE_OPTIONAL_BIT) ? "?" : "";
-
-                formatAppend(result, "R%d: %s%s from %d to %d\n", l.reg, base, optional, l.startpc, l.endpc);
-            }
-        }
-    }
 
     std::vector<int> labels(insns.size(), -1);
 

Compiler/src/Compiler.cpp

@@ -26,9 +26,6 @@ LUAU_FASTINTVARIABLE(LuauCompileInlineThreshold, 25)
 LUAU_FASTINTVARIABLE(LuauCompileInlineThresholdMaxBoost, 300)
 LUAU_FASTINTVARIABLE(LuauCompileInlineDepth, 5)
 
-LUAU_FASTFLAGVARIABLE(LuauCompileUserdataInfo, false)
-LUAU_FASTFLAGVARIABLE(LuauCompileFastcall3, false)
-
 LUAU_FASTFLAG(LuauNativeAttribute)
 
 namespace Luau
@@ -469,18 +466,11 @@ struct Compiler
     {
         LUAU_ASSERT(!expr->self);
         LUAU_ASSERT(expr->args.size >= 1);
-
-        if (FFlag::LuauCompileFastcall3)
         LUAU_ASSERT(expr->args.size <= 3);
-        else
-            LUAU_ASSERT(expr->args.size <= 2 || (bfid == LBF_BIT32_EXTRACTK && expr->args.size == 3));
-
         LUAU_ASSERT(bfid == LBF_BIT32_EXTRACTK ? bfK >= 0 : bfK < 0);
 
         LuauOpcode opc = LOP_NOP;
 
-        if (FFlag::LuauCompileFastcall3)
-        {
         if (expr->args.size == 1)
             opc = LOP_FASTCALL1;
         else if (bfK >= 0 || (expr->args.size == 2 && isConstant(expr->args.data[1])))
@@ -489,13 +479,6 @@ struct Compiler
             opc = LOP_FASTCALL2;
         else
             opc = LOP_FASTCALL3;
-        }
-        else
-        {
-            opc = expr->args.size == 1                                                     ? LOP_FASTCALL1
-                  : (bfK >= 0 || (expr->args.size == 2 && isConstant(expr->args.data[1]))) ? LOP_FASTCALL2K
-                                                                                           : LOP_FASTCALL2;
-        }
 
         uint32_t args[3] = {};
 
@@ -524,7 +507,7 @@ struct Compiler
 
         bytecode.emitABC(opc, uint8_t(bfid), uint8_t(args[0]), 0);
 
-        if (FFlag::LuauCompileFastcall3 && opc == LOP_FASTCALL3)
+        if (opc == LOP_FASTCALL3)
         {
             LUAU_ASSERT(bfK < 0);
             bytecode.emitAux(args[1] | (args[2] << 8));
@@ -886,7 +869,7 @@ struct Compiler
         unsigned maxFastcallArgs = 2;
 
         // Fastcall with 3 arguments is only used if it can help save one or more move instructions
-        if (FFlag::LuauCompileFastcall3 && bfid >= 0 && expr->args.size == 3)
+        if (bfid >= 0 && expr->args.size == 3)
         {
             for (size_t i = 0; i < expr->args.size; ++i)
             {
@@ -899,7 +882,7 @@ struct Compiler
         }
 
         // Optimization: for 1/2/3 argument fast calls use specialized opcodes
-        if (bfid >= 0 && expr->args.size >= 1 && expr->args.size <= (FFlag::LuauCompileFastcall3 ? maxFastcallArgs : 2u))
+        if (bfid >= 0 && expr->args.size >= 1 && expr->args.size <= maxFastcallArgs)
         {
             if (!isExprMultRet(expr->args.data[expr->args.size - 1]))
             {
@@ -4231,8 +4214,6 @@ void compileOrThrow(BytecodeBuilder& bytecode, const ParseResult& parseResult, c
         predictTableShapes(compiler.tableShapes, root);
     }
 
-    if (FFlag::LuauCompileUserdataInfo)
-    {
     if (const char* const* ptr = options.userdataTypes)
     {
         for (; *ptr; ++ptr)
@@ -4245,7 +4226,6 @@ void compileOrThrow(BytecodeBuilder& bytecode, const ParseResult& parseResult, c
         if (uintptr_t(ptr - options.userdataTypes) > (LBC_TYPE_TAGGED_USERDATA_END - LBC_TYPE_TAGGED_USERDATA_BASE))
             CompileError::raise(root->location, "Exceeded userdata type limit in the compilation options");
     }
-    }
 
     // computes type information for all functions based on type annotations
     if (options.typeInfoLevel >= 1)

Compiler/src/Types.cpp

@@ -3,8 +3,6 @@
 
 #include "Luau/BytecodeBuilder.h"
 
-LUAU_FASTFLAG(LuauCompileUserdataInfo)
-
 namespace Luau
 {
 
@@ -70,14 +68,11 @@ static LuauBytecodeType getType(
         if (LuauBytecodeType prim = getPrimitiveType(ref->name); prim != LBC_TYPE_INVALID)
             return prim;
 
-        if (FFlag::LuauCompileUserdataInfo)
-        {
         if (const uint8_t* userdataIndex = userdataTypes.find(ref->name))
         {
             bytecode.useUserdataType(*userdataIndex);
             return LuauBytecodeType(LBC_TYPE_TAGGED_USERDATA_BASE + *userdataIndex);
         }
-        }
 
         // not primitive or alias or generic => host-provided, we assume userdata for now
         return LBC_TYPE_USERDATA;

fuzz/proto.cpp

@@ -56,7 +56,7 @@ LUAU_FASTINT(LuauTypeInferIterationLimit)
 LUAU_FASTINT(LuauTarjanChildLimit)
 LUAU_FASTFLAG(DebugLuauFreezeArena)
 LUAU_FASTFLAG(DebugLuauAbortingChecks)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 std::chrono::milliseconds kInterruptTimeout(10);
 std::chrono::time_point<std::chrono::system_clock> interruptDeadline;
@@ -247,7 +247,7 @@ DEFINE_PROTO_FUZZER(const luau::ModuleSet& message)
 
     FFlag::DebugLuauFreezeArena.value = true;
     FFlag::DebugLuauAbortingChecks.value = true;
-    FFlag::DebugLuauDeferredConstraintResolution.value = kFuzzUseNewSolver;
+    FFlag::LuauSolverV2.value = kFuzzUseNewSolver;
 
     std::vector<std::string> sources = protoprint(message, kFuzzTypes);
 

tests/AnyTypeSummary.test.cpp

@@ -14,7 +14,7 @@ using namespace Luau;
 
 using Pattern = AnyTypeSummary::Pattern;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(DebugLuauFreezeArena)
 LUAU_FASTFLAG(DebugLuauMagicTypes)
 LUAU_FASTFLAG(StudioReportLuauAny2)
@@ -35,7 +35,7 @@ TEST_SUITE_BEGIN("AnyTypeSummaryTest");
 TEST_CASE_FIXTURE(ATSFixture, "var_typepack_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -56,7 +56,7 @@ type A = (number, string) -> ...any
 TEST_CASE_FIXTURE(ATSFixture, "export_alias")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -77,7 +77,7 @@ export type t8<t8> =  t0 &(<t0 ...>(true | any)->(''))
 TEST_CASE_FIXTURE(ATSFixture, "typepacks")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -103,7 +103,7 @@ end
 TEST_CASE_FIXTURE(ATSFixture, "typepacks_no_ret")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -128,7 +128,7 @@ end
 TEST_CASE_FIXTURE(ATSFixture, "var_typepack_any_gen_table")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -149,7 +149,7 @@ type Pair<T> = {first: T, second: any}
 TEST_CASE_FIXTURE(ATSFixture, "assign_uneq")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -173,7 +173,7 @@ local x, y, z = greetings("Dibri") -- mismatch
 TEST_CASE_FIXTURE(ATSFixture, "var_typepack_any_gen")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -195,7 +195,7 @@ type Pair<T> = (boolean, T) -> ...any
 TEST_CASE_FIXTURE(ATSFixture, "typeof_any_in_func")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -219,7 +219,7 @@ TEST_CASE_FIXTURE(ATSFixture, "typeof_any_in_func")
 TEST_CASE_FIXTURE(ATSFixture, "generic_types")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -249,7 +249,7 @@ foo(addNumbers)
 TEST_CASE_FIXTURE(ATSFixture, "no_annot")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -268,7 +268,7 @@ local character = script.Parent
 TEST_CASE_FIXTURE(ATSFixture, "if_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -302,7 +302,7 @@ end
 TEST_CASE_FIXTURE(ATSFixture, "variadic_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -327,7 +327,7 @@ TEST_CASE_FIXTURE(ATSFixture, "variadic_any")
 TEST_CASE_FIXTURE(ATSFixture, "type_alias_intersection")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -351,7 +351,7 @@ TEST_CASE_FIXTURE(ATSFixture, "type_alias_intersection")
 TEST_CASE_FIXTURE(ATSFixture, "var_func_arg")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -379,7 +379,7 @@ TEST_CASE_FIXTURE(ATSFixture, "var_func_arg")
 TEST_CASE_FIXTURE(ATSFixture, "var_func_apps")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -404,7 +404,7 @@ TEST_CASE_FIXTURE(ATSFixture, "var_func_apps")
 TEST_CASE_FIXTURE(ATSFixture, "CannotExtendTable")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -431,7 +431,7 @@ end
 TEST_CASE_FIXTURE(ATSFixture, "unknown_symbol")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -455,7 +455,7 @@ end
 TEST_CASE_FIXTURE(ATSFixture, "racing_3_short")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -496,7 +496,7 @@ initialize()
 TEST_CASE_FIXTURE(ATSFixture, "racing_collision_2")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -579,7 +579,7 @@ initialize()
 TEST_CASE_FIXTURE(ATSFixture, "racing_spawning_1")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -651,7 +651,7 @@ initialize()
 TEST_CASE_FIXTURE(ATSFixture, "mutually_recursive_generic")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -676,7 +676,7 @@ TEST_CASE_FIXTURE(ATSFixture, "mutually_recursive_generic")
 TEST_CASE_FIXTURE(ATSFixture, "explicit_pack")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -698,7 +698,7 @@ type Bar = Foo<(number, any)>
 TEST_CASE_FIXTURE(ATSFixture, "local_val")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -719,7 +719,7 @@ local a, b, c = 1 :: any
 TEST_CASE_FIXTURE(ATSFixture, "var_any_local")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -743,7 +743,7 @@ local x: number, y: any, z, h: nil = 1, nil
 TEST_CASE_FIXTURE(ATSFixture, "table_uses_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -766,7 +766,7 @@ TEST_CASE_FIXTURE(ATSFixture, "table_uses_any")
 TEST_CASE_FIXTURE(ATSFixture, "typeof_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -789,7 +789,7 @@ TEST_CASE_FIXTURE(ATSFixture, "typeof_any")
 TEST_CASE_FIXTURE(ATSFixture, "table_type_assigned")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -813,7 +813,7 @@ TEST_CASE_FIXTURE(ATSFixture, "table_type_assigned")
 TEST_CASE_FIXTURE(ATSFixture, "simple_func_wo_ret")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -835,7 +835,7 @@ TEST_CASE_FIXTURE(ATSFixture, "simple_func_wo_ret")
 TEST_CASE_FIXTURE(ATSFixture, "simple_func_w_ret")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -858,7 +858,7 @@ TEST_CASE_FIXTURE(ATSFixture, "simple_func_w_ret")
 TEST_CASE_FIXTURE(ATSFixture, "nested_local")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -882,7 +882,7 @@ TEST_CASE_FIXTURE(ATSFixture, "nested_local")
 TEST_CASE_FIXTURE(ATSFixture, "generic_func")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -905,7 +905,7 @@ TEST_CASE_FIXTURE(ATSFixture, "generic_func")
 TEST_CASE_FIXTURE(ATSFixture, "type_alias_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -927,7 +927,7 @@ TEST_CASE_FIXTURE(ATSFixture, "type_alias_any")
 TEST_CASE_FIXTURE(ATSFixture, "multi_module_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 
@@ -960,7 +960,7 @@ TEST_CASE_FIXTURE(ATSFixture, "multi_module_any")
 TEST_CASE_FIXTURE(ATSFixture, "cast_on_cyclic_req")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::StudioReportLuauAny2, true},
     };
 

tests/AstQuery.test.cpp

@@ -6,8 +6,6 @@
 #include "doctest.h"
 #include "Fixture.h"
 
-LUAU_FASTFLAG(LuauFixBindingForGlobalPos);
-
 using namespace Luau;
 
 struct DocumentationSymbolFixture : BuiltinsFixture
@@ -171,7 +169,7 @@ TEST_SUITE_BEGIN("AstQuery");
 
 TEST_CASE_FIXTURE(Fixture, "last_argument_function_call_type")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     check(R"(
 local function foo() return 2 end
@@ -353,7 +351,7 @@ TEST_CASE_FIXTURE(Fixture, "find_expr_ancestry")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "find_binding_at_position_global_start_of_file")
 {
-    ScopedFastFlag sff{FFlag::LuauFixBindingForGlobalPos, true};
+
     check("local x = string.char(1)");
     const Position pos(0, 12);
 

tests/Autocomplete.test.cpp

@@ -110,7 +110,7 @@ struct ACFixtureImpl : BaseType
         );
         freeze(globals.globalTypes);
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             GlobalTypes& globals = this->frontend.globals;
             unfreeze(globals.globalTypes);
@@ -1607,7 +1607,7 @@ return target(a.@1
 
 TEST_CASE_FIXTURE(ACFixture, "type_correct_suggestion_in_table")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution) // CLI-116815 Autocomplete cannot suggest keys while autocompleting inside of a table
+    if (FFlag::LuauSolverV2) // CLI-116815 Autocomplete cannot suggest keys while autocompleting inside of a table
         return;
 
     check(R"(
@@ -2213,7 +2213,7 @@ local fp: @1= f
 
     auto ac = autocomplete('1');
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         REQUIRE_EQ("({ x: number, y: number }) -> number", toString(requireType("f")));
     else
         REQUIRE_EQ("({| x: number, y: number |}) -> number", toString(requireType("f")));
@@ -2264,7 +2264,7 @@ local ec = e(f@5)
 
 TEST_CASE_FIXTURE(ACFixture, "type_correct_suggestion_for_overloads")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution) // CLI-116814 Autocomplete needs to populate expected types for function arguments correctly
+    if (FFlag::LuauSolverV2) // CLI-116814 Autocomplete needs to populate expected types for function arguments correctly
                                                       // (overloads and singletons)
         return;
     check(R"(
@@ -2614,7 +2614,7 @@ end
 
 TEST_CASE_FIXTURE(ACFixture, "suggest_table_keys")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution) // CLI-116812 AutocompleteTest.suggest_table_keys needs to populate expected types for nested
+    if (FFlag::LuauSolverV2) // CLI-116812 AutocompleteTest.suggest_table_keys needs to populate expected types for nested
                                                       // tables without an annotation
         return;
 
@@ -3101,7 +3101,7 @@ TEST_CASE_FIXTURE(ACBuiltinsFixture, "autocomplete_on_string_singletons")
 
 TEST_CASE_FIXTURE(ACFixture, "autocomplete_string_singletons")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution) // CLI-116814 Autocomplete needs to populate expected types for function arguments correctly
+    if (FFlag::LuauSolverV2) // CLI-116814 Autocomplete needs to populate expected types for function arguments correctly
                                                       // (overloads and singletons)
         return;
 
@@ -3210,7 +3210,7 @@ TEST_CASE_FIXTURE(ACFixture, "string_singleton_as_table_key")
 TEST_CASE_FIXTURE(ACFixture, "string_singleton_in_if_statement")
 {
     ScopedFastFlag sff[]{
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     check(R"(
@@ -3294,7 +3294,7 @@ TEST_CASE_FIXTURE(ACFixture, "string_singleton_in_if_statement")
 TEST_CASE_FIXTURE(ACFixture, "string_singleton_in_if_statement2")
 {
     // don't run this when the DCR flag isn't set
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     check(R"(
@@ -3578,7 +3578,7 @@ t.@1
 
     REQUIRE(ac.entryMap.count("m"));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(ac.entryMap["m"].wrongIndexType);
     else
         CHECK(!ac.entryMap["m"].wrongIndexType);
@@ -3760,7 +3760,7 @@ TEST_CASE_FIXTURE(ACFixture, "string_contents_is_available_to_callback")
         declare function require(path: string): any
     )");
 
-    GlobalTypes& globals = FFlag::DebugLuauDeferredConstraintResolution ? frontend.globals : frontend.globalsForAutocomplete;
+    GlobalTypes& globals = FFlag::LuauSolverV2 ? frontend.globals : frontend.globalsForAutocomplete;
 
     std::optional<Binding> require = globals.globalScope->linearSearchForBinding("require");
     REQUIRE(require);
@@ -3787,7 +3787,7 @@ TEST_CASE_FIXTURE(ACFixture, "string_contents_is_available_to_callback")
 
 TEST_CASE_FIXTURE(ACFixture, "autocomplete_response_perf1" * doctest::timeout(0.5))
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return; // FIXME: This test is just barely at the threshhold which makes it very flaky under the new solver
 
     // Build a function type with a large overload set
@@ -3869,7 +3869,7 @@ TEST_CASE_FIXTURE(ACFixture, "string_completion_outside_quotes")
         declare function require(path: string): any
     )");
 
-    GlobalTypes& globals = FFlag::DebugLuauDeferredConstraintResolution ? frontend.globals : frontend.globalsForAutocomplete;
+    GlobalTypes& globals = FFlag::LuauSolverV2 ? frontend.globals : frontend.globalsForAutocomplete;
 
     std::optional<Binding> require = globals.globalScope->linearSearchForBinding("require");
     REQUIRE(require);
@@ -4262,7 +4262,7 @@ foo(@1)
 TEST_CASE_FIXTURE(ACFixture, "anonymous_autofilled_generic_type_pack_vararg")
 {
     // CLI-116932 - Autocomplete on a anonymous function in a function argument should not recommend a function with a generic parameter.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     check(R"(
 local function foo<A>(a: (...A) -> number, ...: A)
@@ -4294,7 +4294,7 @@ foo(@1)
     )");
 
     const std::optional<std::string> EXPECTED_INSERT =
-        FFlag::DebugLuauDeferredConstraintResolution ? "function(...: number): number  end" : "function(...): number  end";
+        FFlag::LuauSolverV2 ? "function(...: number): number  end" : "function(...): number  end";
 
     auto ac = autocomplete('1');
 

tests/Compiler.test.cpp

@@ -22,9 +22,6 @@ LUAU_FASTINT(LuauCompileLoopUnrollThreshold)
 LUAU_FASTINT(LuauCompileLoopUnrollThresholdMaxBoost)
 LUAU_FASTINT(LuauRecursionLimit)
 
-LUAU_FASTFLAG(LuauCompileUserdataInfo)
-LUAU_FASTFLAG(LuauCompileFastcall3)
-
 using namespace Luau;
 
 static std::string compileFunction(const char* source, uint32_t id, int optimizationLevel = 1, bool enableVectors = false)
@@ -3330,8 +3327,6 @@ RETURN R0 0
 
 TEST_CASE("DebugTypes")
 {
-    ScopedFastFlag luauCompileUserdataInfo{FFlag::LuauCompileUserdataInfo, true};
-
     const char* source = R"(
 local up: number = 2
 
@@ -3591,8 +3586,6 @@ RETURN R1 -1
 
 TEST_CASE("Fastcall3")
 {
-    ScopedFastFlag luauCompileFastcall3{FFlag::LuauCompileFastcall3, true};
-
     CHECK_EQ(
         "\n" + compileFunction0(R"(
 local a, b, c = ...
@@ -4898,8 +4891,6 @@ L0: RETURN R0 -1
 
 TEST_CASE("VectorFastCall3")
 {
-    ScopedFastFlag luauCompileFastcall3{FFlag::LuauCompileFastcall3, true};
-
     const char* source = R"(
 local a, b, c = ...
 return Vector3.new(a, b, c)

tests/ConstraintGeneratorFixture.cpp

@@ -2,7 +2,7 @@
 #include "ConstraintGeneratorFixture.h"
 #include "ScopedFlags.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 namespace Luau
 {
@@ -10,7 +10,7 @@ namespace Luau
 ConstraintGeneratorFixture::ConstraintGeneratorFixture()
     : Fixture()
     , mainModule(new Module)
-    , forceTheFlag{FFlag::DebugLuauDeferredConstraintResolution, true}
+    , forceTheFlag{FFlag::LuauSolverV2, true}
 {
     mainModule->name = "MainModule";
     mainModule->humanReadableName = "MainModule";

tests/ConstraintSolver.test.cpp

@@ -4,7 +4,7 @@
 #include "Fixture.h"
 #include "doctest.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 using namespace Luau;
 

tests/DataFlowGraph.test.cpp

@@ -11,12 +11,12 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 struct DataFlowGraphFixture
 {
     // Only needed to fix the operator== reflexivity of an empty Symbol.
-    ScopedFastFlag dcr{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag dcr{FFlag::LuauSolverV2, true};
 
     InternalErrorReporter handle;
 

tests/Differ.test.cpp

@@ -15,7 +15,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 TEST_SUITE_BEGIN("Differ");
 
@@ -234,7 +234,7 @@ TEST_CASE_FIXTURE(DifferFixture, "right_cyclic_table_left_table_property_wrong")
 
 TEST_CASE_FIXTURE(DifferFixture, "equal_table_two_cyclic_tables_are_not_different")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
     local function id<a>(x: a): a
@@ -625,7 +625,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_table_cyclic_diamonds_unraveled")
 TEST_CASE_FIXTURE(DifferFixture, "equal_function_cyclic")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function foo()
@@ -646,7 +646,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_function_cyclic")
 TEST_CASE_FIXTURE(DifferFixture, "equal_function_table_cyclic")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function foo()
@@ -673,7 +673,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_function_table_cyclic")
 TEST_CASE_FIXTURE(DifferFixture, "function_table_self_referential_cyclic")
 {
     // Old solver does not correctly infer function typepacks
-    // ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    // ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function foo()
@@ -692,7 +692,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_table_self_referential_cyclic")
     )");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         compareTypesNe(
             "foo",
             "almostFoo",
@@ -726,7 +726,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_union_cyclic")
 TEST_CASE_FIXTURE(DifferFixture, "equal_intersection_cyclic")
 {
     // Old solver does not correctly refine test types
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo1(x: number)
@@ -804,7 +804,7 @@ TEST_CASE_FIXTURE(DifferFixture, "singleton_string")
 
 TEST_CASE_FIXTURE(DifferFixtureWithBuiltins, "negation")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -879,7 +879,7 @@ TEST_CASE_FIXTURE(DifferFixture, "union_missing")
     )");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         compareTypesNe(
             "foo",
             "almostFoo",
@@ -931,7 +931,7 @@ TEST_CASE_FIXTURE(DifferFixture, "intersection_tables_missing_right")
     )");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         compareTypesNe(
             "foo",
             "almostFoo",
@@ -953,7 +953,7 @@ TEST_CASE_FIXTURE(DifferFixture, "intersection_tables_missing_left")
     )");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         compareTypesNe(
             "foo",
             "almostFoo",
@@ -970,7 +970,7 @@ TEST_CASE_FIXTURE(DifferFixture, "intersection_tables_missing_left")
 TEST_CASE_FIXTURE(DifferFixture, "equal_function")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number)
@@ -988,7 +988,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_function")
 TEST_CASE_FIXTURE(DifferFixture, "equal_function_inferred_ret_length")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function bar(x: number, y: string)
@@ -1012,7 +1012,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_function_inferred_ret_length")
 TEST_CASE_FIXTURE(DifferFixture, "equal_function_inferred_ret_length_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function bar(x: number, y: string)
@@ -1033,7 +1033,7 @@ TEST_CASE_FIXTURE(DifferFixture, "equal_function_inferred_ret_length_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_normal")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: number, z: number)
@@ -1055,7 +1055,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_normal")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_normal_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: number, z: string)
@@ -1077,7 +1077,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_normal_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_ret_normal")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: number, z: string)
@@ -1099,7 +1099,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_ret_normal")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_length")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: number)
@@ -1121,7 +1121,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_length")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string, z: number)
@@ -1143,7 +1143,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_none")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo()
@@ -1165,7 +1165,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_none")
 TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_none_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number)
@@ -1187,7 +1187,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_arg_length_none_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_ret_length")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: number)
@@ -1209,7 +1209,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_ret_length")
 TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string, z: number)
@@ -1231,7 +1231,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_none")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string)
@@ -1253,7 +1253,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_none")
 TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_none_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo()
@@ -1275,7 +1275,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_ret_length_none_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_normal")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string, ...: number)
@@ -1297,7 +1297,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_normal")
 TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_missing")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string, ...: number)
@@ -1319,7 +1319,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_missing")
 TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_missing_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x: number, y: string)
@@ -1341,7 +1341,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_variadic_arg_missing_2")
 TEST_CASE_FIXTURE(DifferFixture, "function_variadic_oversaturation")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     -- allowed to be oversaturated
@@ -1363,7 +1363,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_variadic_oversaturation")
 TEST_CASE_FIXTURE(DifferFixture, "function_variadic_oversaturation_2")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     -- must not be oversaturated
@@ -1385,7 +1385,7 @@ TEST_CASE_FIXTURE(DifferFixture, "function_variadic_oversaturation_2")
 TEST_CASE_FIXTURE(DifferFixture, "generic")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo(x, y)
@@ -1407,7 +1407,7 @@ TEST_CASE_FIXTURE(DifferFixture, "generic")
 TEST_CASE_FIXTURE(DifferFixture, "generic_one_vs_two")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo<X>(x: X, y: X)
@@ -1429,7 +1429,7 @@ TEST_CASE_FIXTURE(DifferFixture, "generic_one_vs_two")
 TEST_CASE_FIXTURE(DifferFixture, "generic_three_or_three")
 {
     // Old solver does not correctly infer function typepacks
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
     function foo<X, Y>(x: X, y: X, z: Y)
@@ -1473,7 +1473,7 @@ TEST_CASE_FIXTURE(DifferFixtureWithBuiltins, "equal_metatable")
 
 TEST_CASE_FIXTURE(DifferFixtureWithBuiltins, "metatable_normal")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
     local metaFoo = {

tests/Error.test.cpp

@@ -6,7 +6,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 TEST_SUITE_BEGIN("ErrorTests");
 
@@ -47,7 +47,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "binary_op_type_function_errors")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(
             "Operator '+' could not be applied to operands of types number and string; there is no corresponding overload for __add",
             toString(result.errors[0])
@@ -66,7 +66,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "unary_op_type_function_errors")
     )");
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(

tests/Fixture.cpp

@@ -22,7 +22,7 @@
 
 static const char* mainModuleName = "MainModule";
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(DebugLuauFreezeArena);
 LUAU_FASTFLAG(DebugLuauLogSolverToJsonFile)
 
@@ -204,7 +204,7 @@ AstStatBlock* Fixture::parse(const std::string& source, const ParseOptions& pars
         // if AST is available, check how lint and typecheck handle error nodes
         if (result.root)
         {
-            if (FFlag::DebugLuauDeferredConstraintResolution)
+            if (FFlag::LuauSolverV2)
             {
                 Mode mode = sourceModule->mode ? *sourceModule->mode : Mode::Strict;
                 ModulePtr module = Luau::check(
@@ -371,7 +371,7 @@ std::optional<TypeId> Fixture::getType(const std::string& name)
     if (!module->hasModuleScope())
         return std::nullopt;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return linearSearchForBinding(module->getModuleScope().get(), name.c_str());
     else
         return lookupName(module->getModuleScope(), name);

tests/Frontend.test.cpp

@@ -12,7 +12,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(DebugLuauFreezeArena);
 LUAU_FASTFLAG(DebugLuauMagicTypes);
 
@@ -164,7 +164,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "automatically_check_dependent_scripts")
     auto bExports = first(bModule->returnType);
     REQUIRE(!!bExports);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ b_value: number }", toString(*bExports));
     else
         CHECK_EQ("{| b_value: number |}", toString(*bExports));
@@ -311,7 +311,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "nocheck_cycle_used_by_checked")
     std::optional<TypeId> cExports = first(cModule->returnType);
     REQUIRE(bool(cExports));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ a: { hello: any }, b: { hello: any } }", toString(*cExports));
     else
         CHECK_EQ("{| a: any, b: any |}", toString(*cExports));
@@ -485,13 +485,13 @@ return {mod_b = 2}
     LUAU_REQUIRE_ERRORS(resultB);
 
     TypeId tyB = requireExportedType("game/B", "btype");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(tyB, opts), "{ x: number }");
     else
         CHECK_EQ(toString(tyB, opts), "{| x: number |}");
 
     TypeId tyA = requireExportedType("game/A", "atype");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(tyA, opts), "{ x: any }");
     else
         CHECK_EQ(toString(tyA, opts), "{| x: any |}");
@@ -501,13 +501,13 @@ return {mod_b = 2}
     LUAU_REQUIRE_ERRORS(resultB);
 
     tyB = requireExportedType("game/B", "btype");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(tyB, opts), "{ x: number }");
     else
         CHECK_EQ(toString(tyB, opts), "{| x: number |}");
 
     tyA = requireExportedType("game/A", "atype");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(tyA, opts), "{ x: any }");
     else
         CHECK_EQ(toString(tyA, opts), "{| x: any |}");
@@ -583,7 +583,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "recheck_if_dependent_script_is_dirty")
     auto bExports = first(bModule->returnType);
     REQUIRE(!!bExports);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ b_value: string }", toString(*bExports));
     else
         CHECK_EQ("{| b_value: string |}", toString(*bExports));
@@ -917,7 +917,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "it_should_be_safe_to_stringify_errors_when_f
     // When this test fails, it is because the TypeIds needed by the error have been deallocated.
     // It is thus basically impossible to predict what will happen when this assert is evaluated.
     // It could segfault, or you could see weird type names like the empty string or <VALUELESS BY EXCEPTION>
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         REQUIRE_EQ(
             R"(Type
     '{ count: string }'
@@ -934,7 +934,7 @@ could not be converted into
 TEST_CASE_FIXTURE(FrontendFixture, "trace_requires_in_nonstrict_mode")
 {
     // The new non-strict mode is not currently expected to signal any errors here.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     fileResolver.source["Module/A"] = R"(
@@ -1003,7 +1003,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "environments")
 
     CheckResult resultB = frontend.check("B");
     // In the new non-strict mode, we do not currently support error reporting for unknown symbols in type positions.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(resultB);
     else
         LUAU_REQUIRE_ERROR_COUNT(1, resultB);
@@ -1111,7 +1111,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "typecheck_twice_for_ast_types")
 TEST_CASE_FIXTURE(FrontendFixture, "imported_table_modification_2")
 {
     // This test describes non-strict mode behavior that is just not currently present in the new non-strict mode.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     frontend.options.retainFullTypeGraphs = false;
@@ -1375,7 +1375,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "checked_modules_have_the_correct_mode")
 
 TEST_CASE_FIXTURE(FrontendFixture, "separate_caches_for_autocomplete")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     fileResolver.source["game/A"] = R"(
         --!nonstrict
@@ -1405,7 +1405,7 @@ TEST_CASE_FIXTURE(FrontendFixture, "separate_caches_for_autocomplete")
 
 TEST_CASE_FIXTURE(FrontendFixture, "no_separate_caches_with_the_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     fileResolver.source["game/A"] = R"(
         --!nonstrict

tests/Generalization.test.cpp

@@ -14,7 +14,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 TEST_SUITE_BEGIN("Generalization");
 
@@ -29,7 +29,7 @@ struct GeneralizationFixture
     DenseHashSet<TypeId> generalizedTypes_{nullptr};
     NotNull<DenseHashSet<TypeId>> generalizedTypes{&generalizedTypes_};
 
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     std::pair<TypeId, FreeType*> freshType()
     {

tests/IrLowering.test.cpp

@@ -15,9 +15,6 @@
 #include <memory>
 #include <string_view>
 
-LUAU_FASTFLAG(LuauCompileUserdataInfo)
-LUAU_FASTFLAG(LuauCompileFastcall3)
-
 static std::string getCodegenAssembly(const char* source, bool includeIrTypes = false, int debugLevel = 1)
 {
     Luau::CodeGen::AssemblyOptions options;
@@ -942,8 +939,6 @@ bb_bytecode_0:
 
 TEST_CASE("FastcallTypeInferThroughLocal")
 {
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileFastcall3, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -994,8 +989,6 @@ bb_bytecode_1:
 
 TEST_CASE("FastcallTypeInferThroughUpvalue")
 {
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileFastcall3, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1124,8 +1117,6 @@ bb_bytecode_4:
 
 TEST_CASE("ArgumentTypeRefinement")
 {
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileFastcall3, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1433,8 +1424,6 @@ bb_2:
 
 TEST_CASE("UnaryTypeResolve")
 {
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileFastcall3, true}};
-
     CHECK_EQ(
         "\n" + getCodegenHeader(R"(
 local function foo(a, b: vector, c)
@@ -1634,37 +1623,12 @@ end
     );
 }
 
-// Temporary test, when we don't compile new typeinfo, but support loading it
-TEST_CASE("CustomUserdataTypesTemp")
-{
-    // This test requires runtime component to be present
-    if (!Luau::CodeGen::isSupported())
-        return;
-
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, false}};
-
-    CHECK_EQ(
-        "\n" + getCodegenHeader(R"(
-local function foo(v: vec2, x: mat3)
-    return v.X * x
-end
-)"),
-        R"(
-; function foo(v, x) line 2
-; R0: userdata [argument 'v']
-; R1: userdata [argument 'x']
-)"
-    );
-}
-
 TEST_CASE("CustomUserdataTypes")
 {
     // This test requires runtime component to be present
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenHeader(R"(
 local function foo(v: vec2, x: mat3)
@@ -1685,8 +1649,6 @@ TEST_CASE("CustomUserdataPropertyAccess")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1724,8 +1686,6 @@ TEST_CASE("CustomUserdataPropertyAccess2")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1765,8 +1725,6 @@ TEST_CASE("CustomUserdataNamecall1")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1815,8 +1773,6 @@ TEST_CASE("CustomUserdataNamecall2")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1868,8 +1824,6 @@ TEST_CASE("CustomUserdataMetamethodDirectFlow")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1904,8 +1858,6 @@ TEST_CASE("CustomUserdataMetamethodDirectFlow2")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1938,8 +1890,6 @@ TEST_CASE("CustomUserdataMetamethodDirectFlow3")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(
@@ -1972,8 +1922,6 @@ TEST_CASE("CustomUserdataMetamethod")
     if (!Luau::CodeGen::isSupported())
         return;
 
-    ScopedFastFlag sffs[]{{FFlag::LuauCompileUserdataInfo, true}};
-
     CHECK_EQ(
         "\n" + getCodegenAssembly(
                    R"(

tests/Linter.test.cpp

@@ -7,7 +7,7 @@
 
 #include "doctest.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauNativeAttribute);
 LUAU_FASTFLAG(LintRedundantNativeAttribute);
 
@@ -1265,7 +1265,7 @@ _ = {
 
 TEST_CASE_FIXTURE(Fixture, "read_write_table_props")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     LintResult result = lint(R"(-- line 1
         type A = {x: number}
@@ -1659,7 +1659,7 @@ table.create(42, {} :: {})
 TEST_CASE_FIXTURE(BuiltinsFixture, "TableOperationsIndexer")
 {
     // CLI-116824 Linter incorrectly issues false positive when taking the length of a unannotated string function argument
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     LintResult result = lint(R"(

tests/Module.test.cpp

@@ -11,7 +11,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(DebugLuauFreezeArena);
 LUAU_FASTINT(LuauTypeCloneIterationLimit);
 
@@ -111,7 +111,7 @@ TEST_CASE_FIXTURE(Fixture, "deepClone_cyclic_table")
     // not, but it's tangental to the core purpose of this test.
 
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     CheckResult result = check(R"(
@@ -283,7 +283,7 @@ TEST_CASE_FIXTURE(Fixture, "clone_class")
 
 TEST_CASE_FIXTURE(Fixture, "clone_free_types")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     TypeArena arena;
     TypeId freeTy = freshType(NotNull{&arena}, builtinTypes, nullptr);
@@ -317,7 +317,7 @@ TEST_CASE_FIXTURE(Fixture, "clone_free_tables")
 TEST_CASE_FIXTURE(BuiltinsFixture, "clone_self_property")
 {
     // CLI-117082 ModuleTests.clone_self_property we don't infer self correctly, instead replacing it with unknown.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     fileResolver.source["Module/A"] = R"(
         --!nonstrict
@@ -415,7 +415,7 @@ type B = A
     auto it = mod->exportedTypeBindings.find("A");
     REQUIRE(it != mod->exportedTypeBindings.end());
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(it->second.type) == "any");
     else
         CHECK(toString(it->second.type) == "*error-type*");

tests/NonStrictTypeChecker.test.cpp

@@ -67,7 +67,7 @@ struct NonStrictTypeCheckerFixture : Fixture
     CheckResult checkNonStrict(const std::string& code)
     {
         ScopedFastFlag flags[] = {
-            {FFlag::DebugLuauDeferredConstraintResolution, true},
+            {FFlag::LuauSolverV2, true},
         };
         LoadDefinitionFileResult res = loadDefinition(definitions);
         LUAU_ASSERT(res.success);
@@ -77,7 +77,7 @@ struct NonStrictTypeCheckerFixture : Fixture
     CheckResult checkNonStrictModule(const std::string& moduleName)
     {
         ScopedFastFlag flags[] = {
-            {FFlag::DebugLuauDeferredConstraintResolution, true},
+            {FFlag::LuauSolverV2, true},
         };
         LoadDefinitionFileResult res = loadDefinition(definitions);
         LUAU_ASSERT(res.success);

tests/NonstrictMode.test.cpp

@@ -16,7 +16,7 @@ TEST_SUITE_BEGIN("NonstrictModeTests");
 
 TEST_CASE_FIXTURE(Fixture, "infer_nullary_function")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         function foo(x, y) end
@@ -39,7 +39,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_nullary_function")
 
 TEST_CASE_FIXTURE(Fixture, "infer_the_maximum_number_of_values_the_function_could_return")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         function getMinCardCountForWidth(width)
@@ -103,7 +103,7 @@ TEST_CASE_FIXTURE(Fixture, "inconsistent_return_types_are_ok")
 
 TEST_CASE_FIXTURE(Fixture, "locals_are_any_by_default")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         local m = 55
@@ -130,7 +130,7 @@ TEST_CASE_FIXTURE(Fixture, "parameters_having_type_any_are_optional")
 
 TEST_CASE_FIXTURE(Fixture, "local_tables_are_not_any")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         local T = {}
@@ -148,7 +148,7 @@ TEST_CASE_FIXTURE(Fixture, "local_tables_are_not_any")
 
 TEST_CASE_FIXTURE(Fixture, "offer_a_hint_if_you_use_a_dot_instead_of_a_colon")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         local T = {}
@@ -163,7 +163,7 @@ TEST_CASE_FIXTURE(Fixture, "offer_a_hint_if_you_use_a_dot_instead_of_a_colon")
 
 TEST_CASE_FIXTURE(Fixture, "table_props_are_any")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         local T = {}
@@ -185,7 +185,7 @@ TEST_CASE_FIXTURE(Fixture, "table_props_are_any")
 
 TEST_CASE_FIXTURE(Fixture, "inline_table_props_are_also_any")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
         local T = {
@@ -261,7 +261,7 @@ TEST_CASE_FIXTURE(Fixture, "delay_function_does_not_require_its_argument_to_retu
 
 TEST_CASE_FIXTURE(Fixture, "inconsistent_module_return_types_are_ok")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
     CheckResult result = check(R"(
         --!nonstrict
 

tests/Normalize.test.cpp

@@ -10,7 +10,7 @@
 #include "Luau/Normalize.h"
 #include "Luau/BuiltinDefinitions.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauNormalizeNotUnknownIntersection)
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
 using namespace Luau;
@@ -142,7 +142,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "table_with_union_prop")
     TypeId a = requireType("a");
     TypeId b = requireType("b");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(!isSubtype(a, b)); // table properties are invariant
     else
         CHECK(isSubtype(a, b));
@@ -159,7 +159,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "table_with_any_prop")
     TypeId a = requireType("a");
     TypeId b = requireType("b");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(!isSubtype(a, b)); // table properties are invariant
     else
         CHECK(isSubtype(a, b));
@@ -219,7 +219,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "tables")
     TypeId c = requireType("c");
     TypeId d = requireType("d");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(!isSubtype(a, b)); // table properties are invariant
     else
         CHECK(isSubtype(a, b));
@@ -231,7 +231,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "tables")
     CHECK(isSubtype(d, a));
     CHECK(!isSubtype(a, d));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(!isSubtype(d, b)); // table properties are invariant
     else
         CHECK(isSubtype(d, b));
@@ -406,7 +406,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "error_suppression")
 
     // We have added this as an exception - the set of inhabitants of any is exactly the set of inhabitants of unknown (since error has no
     // inhabitants). any = err | unknown, so under semantic subtyping, {} U unknown = unknown
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(isSubtype(any, unk));
     }
@@ -415,7 +415,7 @@ TEST_CASE_FIXTURE(IsSubtypeFixture, "error_suppression")
         CHECK(!isSubtype(any, unk));
     }
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(isSubtype(err, str));
     }
@@ -454,7 +454,7 @@ struct NormalizeFixture : Fixture
         CheckResult result = check("type _Res = " + annotation);
         LUAU_REQUIRE_ERROR_COUNT(expectedErrors, result);
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             SourceModule* sourceModule = getMainSourceModule();
             REQUIRE(sourceModule);
@@ -670,7 +670,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "negated_function_is_anything_except_a_funct
 
 TEST_CASE_FIXTURE(NormalizeFixture, "specific_functions_cannot_be_negated")
 {
-    CHECK(nullptr == toNormalizedType("Not<(boolean) -> boolean>", FFlag::DebugLuauDeferredConstraintResolution ? 1 : 0));
+    CHECK(nullptr == toNormalizedType("Not<(boolean) -> boolean>", FFlag::LuauSolverV2 ? 1 : 0));
 }
 
 TEST_CASE_FIXTURE(NormalizeFixture, "trivial_intersection_inhabited")
@@ -711,7 +711,7 @@ TEST_CASE_FIXTURE(Fixture, "higher_order_function_with_annotation")
 {
     // CLI-117088 - Inferring the type of a higher order function with an annotation sometimes doesn't fully constrain the type (there are free types
     // left over).
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     check(R"(
         function apply<a, b>(f: (a) -> b, x)
@@ -781,7 +781,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "narrow_union_of_classes_with_intersection")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "intersection_of_metatables_where_the_metatable_is_top_or_bottom")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("{ @metatable *error-type*, {  } }" == toString(normal("Mt<{}, any> & Mt<{}, err>")));
     else
         CHECK("{ @metatable *error-type*, {|  |} }" == toString(normal("Mt<{}, any> & Mt<{}, err>")));
@@ -878,7 +878,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "classes_and_never")
 TEST_CASE_FIXTURE(NormalizeFixture, "top_table_type")
 {
     CHECK("table" == toString(normal("{} | tbl")));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("{  }" == toString(normal("{} & tbl")));
     else
         CHECK("{|  |}" == toString(normal("{} & tbl")));
@@ -887,7 +887,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "top_table_type")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "negations_of_tables")
 {
-    CHECK(nullptr == toNormalizedType("Not<{}>", FFlag::DebugLuauDeferredConstraintResolution ? 1 : 0));
+    CHECK(nullptr == toNormalizedType("Not<{}>", FFlag::LuauSolverV2 ? 1 : 0));
     CHECK("(boolean | buffer | class | function | number | string | thread)?" == toString(normal("Not<tbl>")));
     CHECK("table" == toString(normal("Not<Not<tbl>>")));
 }
@@ -928,7 +928,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "normalize_unknown")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "read_only_props")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK("{ x: string }" == toString(normal("{ read x: string } & { x: string }"), {true}));
     CHECK("{ x: string }" == toString(normal("{ x: string } & { read x: string }"), {true}));
@@ -936,7 +936,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "read_only_props")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "read_only_props_2")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK(R"({ x: "hello" })" == toString(normal(R"({ x: "hello" } & { x: string })"), {true}));
     CHECK(R"(never)" == toString(normal(R"({ x: "hello" } & { x: "world" })"), {true}));
@@ -944,7 +944,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "read_only_props_2")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "read_only_props_3")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK(R"({ read x: "hello" })" == toString(normal(R"({ read x: "hello" } & { read x: string })"), {true}));
     CHECK("never" == toString(normal(R"({ read x: "hello" } & { read x: "world" })"), {true}));
@@ -1009,7 +1009,7 @@ TEST_CASE_FIXTURE(NormalizeFixture, "cyclic_stack_overflow_2")
 
 TEST_CASE_FIXTURE(NormalizeFixture, "truthy_table_property_and_optional_table_with_optional_prop")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     // { x: ~(false?) }
     TypeId t1 = arena.addType(TableType{TableType::Props{{"x", builtinTypes->truthyType}}, std::nullopt, TypeLevel{}, TableState::Sealed});

tests/Parser.test.cpp

@@ -15,7 +15,7 @@ LUAU_FASTFLAG(LuauLexerLookaheadRemembersBraceType);
 LUAU_FASTINT(LuauRecursionLimit);
 LUAU_FASTINT(LuauTypeLengthLimit);
 LUAU_FASTINT(LuauParseErrorLimit);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauAttributeSyntaxFunExpr);
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctions);
 
@@ -1192,7 +1192,7 @@ until false
 TEST_CASE_FIXTURE(Fixture, "parse_nesting_based_end_detection_local_function")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     try
@@ -1229,7 +1229,7 @@ end
 TEST_CASE_FIXTURE(Fixture, "parse_nesting_based_end_detection_failsafe_earlier")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     try
@@ -2597,7 +2597,7 @@ TEST_CASE_FIXTURE(Fixture, "recovery_of_parenthesized_expressions")
     };
 
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     checkRecovery("function foo(a, b. c) return a + b end", "function foo(a, b) return a + b end", 1);
@@ -2841,7 +2841,7 @@ TEST_CASE_FIXTURE(Fixture, "AstName_comparison")
 TEST_CASE_FIXTURE(Fixture, "generic_type_list_recovery")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     try

tests/RuntimeLimits.test.cpp

@@ -18,7 +18,7 @@
 using namespace Luau;
 
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 struct LimitFixture : BuiltinsFixture
 {
@@ -46,7 +46,7 @@ TEST_SUITE_BEGIN("RuntimeLimits");
 TEST_CASE_FIXTURE(LimitFixture, "typescript_port_of_Result_type")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     constexpr const char* src = R"LUA(

tests/Simplify.test.cpp

@@ -8,7 +8,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_DYNAMIC_FASTINT(LuauSimplificationComplexityLimit)
 
 namespace
@@ -62,7 +62,7 @@ struct SimplifyFixture : Fixture
     TypeId anotherChildClassTy = nullptr;
     TypeId unrelatedClassTy = nullptr;
 
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     SimplifyFixture()
     {

tests/Subtyping.test.cpp

@@ -15,7 +15,7 @@
 
 #include <initializer_list>
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 using namespace Luau;
 
@@ -67,7 +67,7 @@ struct SubtypeFixture : Fixture
     UnifierSharedState sharedState{&ice};
     Normalizer normalizer{&arena, builtinTypes, NotNull{&sharedState}};
 
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     ScopePtr rootScope{new Scope(builtinTypes->emptyTypePack)};
     ScopePtr moduleScope{new Scope(rootScope)};
@@ -837,28 +837,28 @@ TEST_CASE_FIXTURE(SubtypeFixture, "{x: <T>(T) -> ()} <: {x: <U>(U) -> ()}")
 
 TEST_CASE_FIXTURE(SubtypeFixture, "{ x: number } <: { read x: number }")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK_IS_SUBTYPE(tbl({{"x", builtinTypes->numberType}}), tbl({{"x", Property::readonly(builtinTypes->numberType)}}));
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "{ x: number } <: { write x: number }")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK_IS_SUBTYPE(tbl({{"x", builtinTypes->numberType}}), tbl({{"x", Property::writeonly(builtinTypes->numberType)}}));
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "{ x: \"hello\" } <: { read x: string }")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK_IS_SUBTYPE(tbl({{"x", helloType}}), tbl({{"x", Property::readonly(builtinTypes->stringType)}}));
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "{ x: string } <: { write x: string }")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK_IS_SUBTYPE(tbl({{"x", builtinTypes->stringType}}), tbl({{"x", Property::writeonly(builtinTypes->stringType)}}));
 }

tests/Symbol.test.cpp

@@ -8,7 +8,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 TEST_SUITE_BEGIN("SymbolTests");
 
@@ -68,7 +68,7 @@ TEST_CASE("equality_and_hashing_of_locals")
 
 TEST_CASE("equality_of_empty_symbols")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     std::string s1 = "name";
     std::string s2 = "name";

tests/ToDot.test.cpp

@@ -9,7 +9,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 struct ToDotClassFixture : Fixture
 {
@@ -145,7 +145,7 @@ local function f(a, ...: string) return a end
     ToDotOptions opts;
     opts.showPointers = false;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             R"(digraph graphname {
@@ -242,7 +242,7 @@ local a: A<number, ...string>
 
     ToDotOptions opts;
     opts.showPointers = false;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             R"(digraph graphname {
@@ -323,7 +323,7 @@ n3 [label="TableType 3"];
 TEST_CASE_FIXTURE(Fixture, "free")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     Type type{TypeVariant{FreeType{TypeLevel{0, 0}}}};
@@ -341,7 +341,7 @@ n1 [label="FreeType 1"];
 TEST_CASE_FIXTURE(Fixture, "free_with_constraints")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     Type type{TypeVariant{FreeType{nullptr, builtinTypes->numberType, builtinTypes->optionalNumberType}}};

tests/ToString.test.cpp

@@ -11,7 +11,7 @@
 using namespace Luau;
 
 LUAU_FASTFLAG(LuauRecursiveTypeParameterRestriction);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauAttributeSyntax);
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctions)
 
@@ -22,7 +22,7 @@ TEST_CASE_FIXTURE(Fixture, "primitive")
     CheckResult result = check("local a = nil    local b = 44    local c = 'lalala'    local d = true");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("nil" == toString(requireType("a")));
     else
     {
@@ -45,7 +45,7 @@ TEST_CASE_FIXTURE(Fixture, "bound_types")
 
 TEST_CASE_FIXTURE(Fixture, "free_types")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check("local a");
     LUAU_REQUIRE_NO_ERRORS(result);
@@ -59,7 +59,7 @@ TEST_CASE_FIXTURE(Fixture, "cyclic_table")
     TableType* tableOne = getMutable<TableType>(&cyclicTable);
     tableOne->props["self"] = {&cyclicTable};
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("t1 where t1 = {| self: t1 |}", toString(&cyclicTable));
     else
         CHECK_EQ("t1 where t1 = { self: t1 }", toString(&cyclicTable));
@@ -80,7 +80,7 @@ TEST_CASE_FIXTURE(Fixture, "empty_table")
         local a: {}
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{  }", toString(requireType("a")));
     else
         CHECK_EQ("{|  |}", toString(requireType("a")));
@@ -88,7 +88,7 @@ TEST_CASE_FIXTURE(Fixture, "empty_table")
     // Should stay the same with useLineBreaks enabled
     ToStringOptions opts;
     opts.useLineBreaks = true;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{  }", toString(requireType("a"), opts));
     else
         CHECK_EQ("{|  |}", toString(requireType("a"), opts));
@@ -103,7 +103,7 @@ TEST_CASE_FIXTURE(Fixture, "table_respects_use_line_break")
     ToStringOptions opts;
     opts.useLineBreaks = true;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(
             "{\n"
             "    anotherProp: number,\n"
@@ -150,7 +150,7 @@ TEST_CASE_FIXTURE(Fixture, "metatable")
     Type table{TypeVariant(TableType())};
     Type metatable{TypeVariant(TableType())};
     Type mtv{TypeVariant(MetatableType{&table, &metatable})};
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ @metatable {|  |}, {|  |} }", toString(&mtv));
     else
         CHECK_EQ("{ @metatable {  }, {  } }", toString(&mtv));
@@ -166,7 +166,7 @@ TEST_CASE_FIXTURE(Fixture, "named_metatable")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "named_metatable_toStringNamedFunction")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function createTbl(): NamedMetatable
@@ -207,7 +207,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "exhaustive_toString_of_cyclic_table")
     CHECK_EQ(std::string::npos, a.find("CYCLE"));
     CHECK_EQ(std::string::npos, a.find("TRUNCATED"));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(
             "t2 where "
@@ -346,7 +346,7 @@ TEST_CASE_FIXTURE(Fixture, "quit_stringifying_table_type_when_length_is_exceeded
     ToStringOptions o;
     o.exhaustive = false;
     o.maxTableLength = 40;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(&tv, o), "{| a: number, b: number, c: number, d: number, e: number, ... 10 more ... |}");
     else
         CHECK_EQ(toString(&tv, o), "{ a: number, b: number, c: number, d: number, e: number, ... 10 more ... }");
@@ -363,7 +363,7 @@ TEST_CASE_FIXTURE(Fixture, "stringifying_table_type_is_still_capped_when_exhaust
     ToStringOptions o;
     o.exhaustive = true;
     o.maxTableLength = 40;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(&tv, o), "{| a: number, b: number, c: number, d: number, e: number, ... 2 more ... |}");
     else
         CHECK_EQ(toString(&tv, o), "{ a: number, b: number, c: number, d: number, e: number, ... 2 more ... }");
@@ -377,7 +377,7 @@ TEST_CASE_FIXTURE(Fixture, "quit_stringifying_type_when_length_is_exceeded")
         function f2(f) return f or f1 end
         function f3(f) return f or f2 end
     )");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
 
@@ -412,7 +412,7 @@ TEST_CASE_FIXTURE(Fixture, "stringifying_type_is_still_capped_when_exhaustive")
         function f3(f) return f or f2 end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
 
@@ -448,7 +448,7 @@ TEST_CASE_FIXTURE(Fixture, "stringifying_table_type_correctly_use_matching_table
 
     ToStringOptions o;
     o.maxTableLength = 40;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(&tv, o), "{ a: number, b: number, c: number, d: number, e: number, ... 5 more ... }");
     else
         CHECK_EQ(toString(&tv, o), "{| a: number, b: number, c: number, d: number, e: number, ... 5 more ... |}");
@@ -482,7 +482,7 @@ TEST_CASE_FIXTURE(Fixture, "stringifying_array_uses_array_syntax")
     CHECK_EQ("{string}", toString(Type{ttv}));
 
     ttv.props["A"] = {builtinTypes->numberType};
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ [number]: string, A: number }", toString(Type{ttv}));
     else
         CHECK_EQ("{| [number]: string, A: number |}", toString(Type{ttv}));
@@ -594,7 +594,7 @@ TEST_CASE_FIXTURE(Fixture, "toStringDetailed")
 
 TEST_CASE_FIXTURE(Fixture, "toStringErrorPack")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local function target(callback: nil) return callback(4, "hello") end
@@ -633,7 +633,7 @@ TEST_CASE_FIXTURE(Fixture, "toString_the_boundTo_table_type_contained_within_a_T
     TypePackVar tpv2{TypePack{{&tv2}}};
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("{ hello: number, world: number }", toString(&tpv1));
         CHECK_EQ("{ hello: number, world: number }", toString(&tpv2));
@@ -680,7 +680,7 @@ TEST_CASE_FIXTURE(Fixture, "no_parentheses_around_cyclic_function_type_in_inters
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(() -> t1) & ((number) -> ()) where t1 = () -> t1" == toString(requireType("a")));
     else
         CHECK_EQ("((number) -> ()) & t1 where t1 = () -> t1", toString(requireType("a")));
@@ -723,7 +723,7 @@ TEST_CASE_FIXTURE(Fixture, "toStringNamedFunction_map")
     TypeId ty = requireType("map");
     const FunctionType* ftv = get<FunctionType>(follow(ty));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("map<a, b>(arr: {a}, fn: (a) -> (b, ...unknown)): {b}", toStringNamedFunction("map", *ftv));
     else
         CHECK_EQ("map<a, b>(arr: {a}, fn: (a) -> b): {b}", toStringNamedFunction("map", *ftv));
@@ -841,7 +841,7 @@ TEST_CASE_FIXTURE(Fixture, "pick_distinct_names_for_mixed_explicit_and_implicit_
         function foo<a>(x: a, y) end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("<a>(a, 'b) -> ()" == toString(requireType("foo")));
     }
@@ -873,7 +873,7 @@ TEST_CASE_FIXTURE(Fixture, "tostring_error_mismatch")
     )");
 
     std::string expected;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         expected =
             R"(Type pack '{ a: number, b: string, c: { d: string } }' could not be converted into '{ a: number, b: string, c: { d: number } }'; at [0][read "c"][read "d"], string is not exactly number)";
     else
@@ -901,7 +901,7 @@ Type 'string' could not be converted into 'number' in an invariant context)";
 TEST_CASE_FIXTURE(Fixture, "checked_fn_toString")
 {
     ScopedFastFlag flags[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     auto _result = loadDefinition(R"(
@@ -920,7 +920,7 @@ local f = abs
 
 TEST_CASE_FIXTURE(Fixture, "read_only_properties")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type A = {x: string}
@@ -950,7 +950,7 @@ TEST_CASE_FIXTURE(Fixture, "cycle_rooted_in_a_pack")
 
     packPtr->head[0] = theTable;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("tp1 where tp1 = { read BaseField: unknown, read BaseMethod: (tp1) -> () }, number" == toString(thePack));
     else
         CHECK("tp1 where tp1 = {| BaseField: unknown, BaseMethod: (tp1) -> () |}, number" == toString(thePack));
@@ -969,7 +969,7 @@ TEST_CASE_FIXTURE(Fixture, "correct_stringification_user_defined_type_functions"
 
     Type tv{tftt};
 
-    if (FFlag::DebugLuauDeferredConstraintResolution && FFlag::LuauUserDefinedTypeFunctions)
+    if (FFlag::LuauSolverV2 && FFlag::LuauUserDefinedTypeFunctions)
         CHECK_EQ(toString(&tv, {}), "woohoo<number>");
 }
 

tests/TxnLog.test.cpp

@@ -12,7 +12,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 struct TxnLogFixture
 {
@@ -35,7 +35,7 @@ TEST_SUITE_BEGIN("TxnLog");
 
 TEST_CASE_FIXTURE(TxnLogFixture, "colliding_union_incoming_type_has_greater_scope")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     log.replace(c, BoundType{a});
     log2.replace(a, BoundType{c});
@@ -68,7 +68,7 @@ TEST_CASE_FIXTURE(TxnLogFixture, "colliding_union_incoming_type_has_greater_scop
 
 TEST_CASE_FIXTURE(TxnLogFixture, "colliding_union_incoming_type_has_lesser_scope")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     log.replace(a, BoundType{c});
     log2.replace(c, BoundType{a});
@@ -101,7 +101,7 @@ TEST_CASE_FIXTURE(TxnLogFixture, "colliding_union_incoming_type_has_lesser_scope
 
 TEST_CASE_FIXTURE(TxnLogFixture, "colliding_coincident_logs_do_not_create_degenerate_unions")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     log.replace(a, BoundType{b});
     log2.replace(a, BoundType{b});

tests/TypeFunction.test.cpp

@@ -12,7 +12,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctions)
 LUAU_DYNAMIC_FASTINT(LuauTypeFamilyApplicationCartesianProductLimit)
 
@@ -67,7 +67,7 @@ TEST_SUITE_BEGIN("TypeFunctionTests");
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "basic_type_function")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -89,7 +89,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "basic_type_function")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "function_as_fn_ret")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -108,7 +108,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "function_as_fn_ret")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "function_as_fn_arg")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -126,7 +126,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "function_as_fn_arg")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "resolve_deep_functions")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -139,7 +139,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "resolve_deep_functions")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "unsolvable_function")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -159,7 +159,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "unsolvable_function")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "table_internal_functions")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -179,7 +179,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "table_internal_functions")
 
 TEST_CASE_FIXTURE(TypeFunctionFixture, "function_internal_functions")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -200,7 +200,7 @@ TEST_CASE_FIXTURE(TypeFunctionFixture, "function_internal_functions")
 
 TEST_CASE_FIXTURE(Fixture, "add_function_at_work")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -229,7 +229,7 @@ TEST_CASE_FIXTURE(Fixture, "add_function_at_work")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "cyclic_add_function_at_work")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -242,7 +242,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "cyclic_add_function_at_work")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "mul_function_with_union_of_multiplicatives")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     loadDefinition(R"(
@@ -265,7 +265,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "mul_function_with_union_of_multiplicatives")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "mul_function_with_union_of_multiplicatives_2")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     loadDefinition(R"(
@@ -285,7 +285,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "mul_function_with_union_of_multiplicatives_2
 
 TEST_CASE_FIXTURE(Fixture, "internal_functions_raise_errors")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -303,7 +303,7 @@ TEST_CASE_FIXTURE(Fixture, "internal_functions_raise_errors")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "type_functions_can_be_shadowed")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -328,7 +328,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_functions_can_be_shadowed")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "type_functions_inhabited_with_normalization")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -346,7 +346,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_functions_inhabited_with_normalization"
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_works")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -367,7 +367,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_works")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_works_with_metatables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -390,7 +390,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_works_with_metatables")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_errors_if_it_has_nontable_part")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -408,7 +408,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_errors_if_it_has_nontabl
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_string_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -436,7 +436,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_string_indexer")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_common_subset_if_union_of_differing_tables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -457,7 +457,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_common_subset_if_union_o
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_never_for_empty_table")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -472,7 +472,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_function_never_for_empty_table")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_works")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -493,7 +493,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_works")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_ignores_metatables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -516,7 +516,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_ignores_metatables")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_errors_if_it_has_nontable_part")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -534,7 +534,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_errors_if_it_has_nont
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_common_subset_if_union_of_differing_tables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -555,7 +555,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_common_subset_if_unio
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_never_for_empty_table")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -570,7 +570,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_function_never_for_empty_table
 
 TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_works_on_classes")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -590,7 +590,7 @@ TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_works_on_classes")
 
 TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_errors_if_it_has_nonclass_part")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -607,7 +607,7 @@ TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_errors_if_it_has_nonclass_p
 
 TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_common_subset_if_union_of_differing_classes")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -621,7 +621,7 @@ TEST_CASE_FIXTURE(ClassFixture, "keyof_type_function_common_subset_if_union_of_d
 
 TEST_CASE_FIXTURE(ClassFixture, "binary_type_function_works_with_default_argument")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -636,7 +636,7 @@ TEST_CASE_FIXTURE(ClassFixture, "binary_type_function_works_with_default_argumen
 
 TEST_CASE_FIXTURE(ClassFixture, "vector2_multiply_is_overloaded")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -659,7 +659,7 @@ TEST_CASE_FIXTURE(ClassFixture, "vector2_multiply_is_overloaded")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_rfc_example")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -690,7 +690,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_rfc_example")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_oss_crash_gh1161")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -730,7 +730,7 @@ _(setmetatable(_,{[...]=_,}))
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "cyclic_concat_function_at_work")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -743,7 +743,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "cyclic_concat_function_at_work")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "exceeded_distributivity_limits")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     ScopedFastInt sfi{DFInt::LuauTypeFamilyApplicationCartesianProductLimit, 10};
@@ -776,7 +776,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "exceeded_distributivity_limits")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "didnt_quite_exceed_distributivity_limits")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     // We duplicate the test here because we want to make sure the test failed
@@ -810,7 +810,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "didnt_quite_exceed_distributivity_limits")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "ensure_equivalence_with_distributivity")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     loadDefinition(R"(
@@ -843,7 +843,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "ensure_equivalence_with_distributivity")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "we_shouldnt_warn_that_a_reducible_type_function_is_uninhabited")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -873,7 +873,7 @@ end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -896,7 +896,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_array")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -911,7 +911,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_array")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_generic_types")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -933,7 +933,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_generic_types")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_errors_w_bad_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -949,7 +949,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_errors_w_bad_indexer")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_errors_w_var_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -966,7 +966,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_errors_w_var_indexer")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_union_type_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -984,7 +984,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_union_type_index
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_union_type_indexee")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1003,7 +1003,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_union_type_index
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_rfc_alternative_section")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1021,7 +1021,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_rfc_alternative_section"
 
 TEST_CASE_FIXTURE(ClassFixture, "index_type_function_works_on_classes")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1035,7 +1035,7 @@ TEST_CASE_FIXTURE(ClassFixture, "index_type_function_works_on_classes")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_index_metatables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1061,7 +1061,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_type_function_works_w_index_metatables
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1083,7 +1083,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_array")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1097,7 +1097,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_array")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_errors_w_var_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1113,7 +1113,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_errors_w_var_indexer")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_union_type_indexer")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1129,7 +1129,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_union_type_inde
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_union_type_indexee")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1146,7 +1146,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_union_type_inde
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_index_metatables")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1166,7 +1166,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawget_type_function_works_w_index_metatable
 
 TEST_CASE_FIXTURE(ClassFixture, "rawget_type_function_errors_w_classes")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(

tests/TypeInfer.aliases.test.cpp

@@ -8,7 +8,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctions)
 
 TEST_SUITE_BEGIN("TypeAliases");
@@ -72,7 +72,7 @@ TEST_CASE_FIXTURE(Fixture, "cannot_steal_hoisted_type_alias")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(
             result.errors[0] ==
@@ -105,7 +105,7 @@ TEST_CASE_FIXTURE(Fixture, "cannot_steal_hoisted_type_alias")
 TEST_CASE_FIXTURE(Fixture, "mismatched_generic_type_param")
 {
     // We erroneously report an extra error in this case when the new solver is enabled.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type T<A> = (A...) -> ()
@@ -205,7 +205,7 @@ TEST_CASE_FIXTURE(Fixture, "mutually_recursive_aliases")
 TEST_CASE_FIXTURE(Fixture, "generic_aliases")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
     CheckResult result = check(R"(
         type T<a> = { v: a }
@@ -223,7 +223,7 @@ TEST_CASE_FIXTURE(Fixture, "generic_aliases")
 TEST_CASE_FIXTURE(Fixture, "dependent_generic_aliases")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     CheckResult result = check(R"(
@@ -244,7 +244,7 @@ TEST_CASE_FIXTURE(Fixture, "dependent_generic_aliases")
 TEST_CASE_FIXTURE(Fixture, "mutually_recursive_generic_aliases")
 {
     // CLI-116108
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -344,7 +344,7 @@ TEST_CASE_FIXTURE(Fixture, "stringify_type_alias_of_recursive_template_table_typ
 
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("t1 where t1 = ({ a: t1 }) -> string", toString(tm->wantedType));
     else
         CHECK_EQ("t1 where t1 = ({| a: t1 |}) -> string", toString(tm->wantedType));
@@ -355,7 +355,7 @@ TEST_CASE_FIXTURE(Fixture, "stringify_type_alias_of_recursive_template_table_typ
 TEST_CASE_FIXTURE(Fixture, "cli_38393_recursive_intersection_oom")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     }; // FIXME
 
     CheckResult result = check(R"(
@@ -417,7 +417,7 @@ TEST_CASE_FIXTURE(Fixture, "corecursive_function_types")
 
 TEST_CASE_FIXTURE(Fixture, "generic_param_remap")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     const std::string code = R"(
         -- An example of a forwarded use of a type that has different type arguments than parameters
@@ -543,7 +543,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_import_mutation")
 
 TEST_CASE_FIXTURE(Fixture, "type_alias_local_mutation")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Cool = { a: number, b: string }
@@ -564,7 +564,7 @@ TEST_CASE_FIXTURE(Fixture, "type_alias_local_mutation")
 
 TEST_CASE_FIXTURE(Fixture, "type_alias_local_rename")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type Cool = { a: number, b: string }
@@ -660,7 +660,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_of_an_imported_recursive_generic_
     ty2 = lookupType("X");
     REQUIRE(ty2);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(toString(*ty1, {true}) == "t1 where t1 = { C: t1?, a: T, b: U }");
         CHECK(toString(*ty2, {true}) == "t1 where t1 = { C: t1?, a: U, b: T }");
@@ -712,7 +712,7 @@ TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_ok")
 TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_not_ok_1")
 {
     // CLI-116108
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         -- OK because forwarded types are used with their parameters.
@@ -726,7 +726,7 @@ TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_not_ok_1")
 TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_not_ok_2")
 {
     // CLI-116108
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         -- Not OK because forwarded types are used with different types than their parameters.
@@ -750,7 +750,7 @@ TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_swapsies_ok")
 TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_swapsies_not_ok")
 {
     // CLI-116108
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Tree1<T,U> = { data: T, children: {Tree2<U,T>} }
@@ -855,7 +855,7 @@ TEST_CASE_FIXTURE(Fixture, "forward_declared_alias_is_not_clobbered_by_prior_uni
         local d: FutureType = { smth = true } -- missing error, 'd' is resolved to 'any'
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ foo: number }", toString(requireType("d"), {true}));
     else
         CHECK_EQ("{| foo: number |}", toString(requireType("d"), {true}));
@@ -875,7 +875,7 @@ TEST_CASE_FIXTURE(Fixture, "recursive_types_restriction_ok")
 TEST_CASE_FIXTURE(Fixture, "recursive_types_restriction_not_ok")
 {
     // CLI-116108
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         -- this would be an infinite type if we allowed it
@@ -888,7 +888,7 @@ TEST_CASE_FIXTURE(Fixture, "recursive_types_restriction_not_ok")
 TEST_CASE_FIXTURE(Fixture, "report_shadowed_aliases")
 {
     // CLI-116110
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     // We allow a previous type alias to depend on a future type alias. That exact feature enables a confusing example, like the following snippet,
     // which has the type alias FakeString point to the type alias `string` that which points to `number`.
@@ -972,7 +972,7 @@ TEST_CASE_FIXTURE(Fixture, "type_alias_locations")
 TEST_CASE_FIXTURE(BuiltinsFixture, "dont_lose_track_of_PendingExpansionTypes_after_substitution")
 {
     // CLI-114134 - We need egraphs to properly simplify these types.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     fileResolver.source["game/ReactCurrentDispatcher"] = R"(
         export type BasicStateAction<S> = ((S) -> S) | S
@@ -1115,7 +1115,7 @@ type Foo<T> = Foo<T>
 
 TEST_CASE_FIXTURE(Fixture, "recursive_type_alias_bad_pack_use_warns")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1155,7 +1155,7 @@ type Foo<T> = Foo<T> | string
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_adds_reduce_constraint_for_type_function")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution || !FFlag::LuauUserDefinedTypeFunctions)
+    if (!FFlag::LuauSolverV2 || !FFlag::LuauUserDefinedTypeFunctions)
         return;
 
     CheckResult result = check(R"(

tests/TypeInfer.annotations.test.cpp

@@ -7,7 +7,7 @@
 
 #include "doctest.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(DebugLuauMagicTypes);
 
 using namespace Luau;
@@ -78,7 +78,7 @@ TEST_CASE_FIXTURE(Fixture, "assignment_cannot_transform_a_table_property_type")
 
 TEST_CASE_FIXTURE(Fixture, "assignments_to_unannotated_parameters_can_transform_the_type")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(x)
@@ -94,7 +94,7 @@ TEST_CASE_FIXTURE(Fixture, "assignments_to_unannotated_parameters_can_transform_
 
 TEST_CASE_FIXTURE(Fixture, "assignments_to_annotated_parameters_are_checked")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(x: string)
@@ -264,7 +264,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_of_value_a_via_typeof_with_assignment")
         a = "foo"
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("string?" == toString(requireType("a")));
         CHECK("nil" == toString(requireType("b")));

tests/TypeInfer.anyerror.test.cpp

@@ -13,7 +13,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("TypeInferAnyError");
 
@@ -32,7 +32,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_returns_any")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any?" == toString(requireType("a")));
     else
         CHECK(builtinTypes->anyType == requireType("a"));
@@ -53,7 +53,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_returns_any2")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any?" == toString(requireType("a")));
     else
         CHECK("any" == toString(requireType("a")));
@@ -72,7 +72,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_is_any")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any?" == toString(requireType("a")));
     else
         CHECK("any" == toString(requireType("a")));
@@ -89,7 +89,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_is_any2")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any?" == toString(requireType("a")));
     else
         CHECK("any" == toString(requireType("a")));
@@ -108,7 +108,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_is_any_pack")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any?" == toString(requireType("a")));
     else
         CHECK("any" == toString(requireType("a")));
@@ -126,7 +126,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_is_error")
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // Bug: We do not simplify at the right time
         CHECK_EQ("*error-type*?", toString(requireType("a")));
@@ -148,7 +148,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_iterator_is_error2")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-97375(awe): `bar()` is returning `nil` here, which isn't wrong necessarily,
         // but then we're signaling an additional error for the access on `nil`.
@@ -277,7 +277,7 @@ TEST_CASE_FIXTURE(Fixture, "calling_error_type_yields_error")
 
     CHECK_EQ("unknown", err->name);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("any", toString(requireType("a")));
     else
         CHECK_EQ("*error-type*", toString(requireType("a")));
@@ -289,7 +289,7 @@ TEST_CASE_FIXTURE(Fixture, "chain_calling_error_type_yields_error")
         local a = Utility.Create "Foo" {}
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("any", toString(requireType("a")));
     else
         CHECK_EQ("*error-type*", toString(requireType("a")));
@@ -307,7 +307,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "replace_every_free_type_when_unifying_a_comp
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("any?", toString(requireType("b")));
     else
         CHECK_EQ("any", toString(requireType("b")));

tests/TypeInfer.builtins.test.cpp

@@ -8,7 +8,8 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
+LUAU_FASTFLAG(LuauDCRMagicFunctionTypeChecker);
 
 TEST_SUITE_BEGIN("BuiltinTests");
 
@@ -132,7 +133,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "sort_with_predicate")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "sort_with_bad_predicate")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -414,7 +415,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_pack")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ [number]: boolean | number | string, n: number }", toString(requireType("t")));
     else
         CHECK_EQ("{| [number]: boolean | number | string, n: number |}", toString(requireType("t")));
@@ -432,7 +433,7 @@ local t = table.pack(f())
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ [number]: number | string, n: number }", toString(requireType("t")));
     else
         CHECK_EQ("{| [number]: number | string, n: number |}", toString(requireType("t")));
@@ -445,7 +446,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_pack_reduce")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ [number]: boolean | number, n: number }", toString(requireType("t")));
     else
         CHECK_EQ("{| [number]: boolean | number, n: number |}", toString(requireType("t")));
@@ -455,7 +456,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_pack_reduce")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ [number]: string, n: number }", toString(requireType("t")));
     else
         CHECK_EQ("{| [number]: string, n: number |}", toString(requireType("t")));
@@ -512,7 +513,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "buffer_is_a_type")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "coroutine_resume_anything_goes")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function nifty(x, y)
@@ -551,7 +552,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "coroutine_wrap_anything_goes")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "setmetatable_should_not_mutate_persisted_types")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -599,7 +600,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "string_format_arg_count_mismatch")
 TEST_CASE_FIXTURE(BuiltinsFixture, "string_format_correctly_ordered_types")
 {
     // CLI-115690
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -703,7 +704,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "bad_select_should_not_crash")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // Counterintuitively, the parameter l0 is unconstrained and therefore it is valid to pass nil.
         // The new solver therefore considers that parameter to be optional.
@@ -721,7 +722,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "bad_select_should_not_crash")
 TEST_CASE_FIXTURE(BuiltinsFixture, "select_way_out_of_range")
 {
     // CLI-115720
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -736,7 +737,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "select_way_out_of_range")
 TEST_CASE_FIXTURE(BuiltinsFixture, "select_slightly_out_of_range")
 {
     // CLI-115720
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -770,7 +771,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "select_with_variadic_typepack_tail")
 TEST_CASE_FIXTURE(BuiltinsFixture, "select_with_variadic_typepack_tail_and_string_head")
 {
     // CLI-115720
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -793,7 +794,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "select_with_variadic_typepack_tail_and_strin
 TEST_CASE_FIXTURE(Fixture, "string_format_as_method")
 {
     // CLI-115690
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check("local _ = ('%s'):format(5)");
@@ -820,7 +821,7 @@ TEST_CASE_FIXTURE(Fixture, "string_format_use_correct_argument")
 TEST_CASE_FIXTURE(Fixture, "string_format_use_correct_argument2")
 {
     // CLI-115690
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -882,7 +883,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "debug_info_is_crazy")
 TEST_CASE_FIXTURE(BuiltinsFixture, "aliased_string_format")
 {
     // CLI-115690
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -945,9 +946,10 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "select_on_variadic")
 TEST_CASE_FIXTURE(BuiltinsFixture, "string_format_report_all_type_errors_at_correct_positions")
 {
     // CLI-115690
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
+    ScopedFastFlag sff{FFlag::LuauDCRMagicFunctionTypeChecker, true};
     CheckResult result = check(R"(
         ("%s%d%s"):format(1, "hello", true)
         string.format("%s%d%s", 1, "hello", true)
@@ -986,7 +988,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "tonumber_returns_optional_number_type")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(
             "Type 'number?' could not be converted into 'number'; type number?[1] (nil) is not a subtype of number (number)",
             toString(result.errors[0])
@@ -1009,7 +1011,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dont_add_definitions_to_persistent_types")
 {
     // This test makes no sense with type states and I think it generally makes no sense under the new solver.
     // TODO: clip.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1042,7 +1044,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "assert_removes_falsy_types")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("((boolean | number)?) -> number | true", toString(requireType("f")));
     else
         CHECK_EQ("((boolean | number)?) -> boolean | number", toString(requireType("f")));
@@ -1070,7 +1072,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "assert_removes_falsy_types3")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("((boolean | number)?) -> number | true", toString(requireType("f")));
     else // without the annotation, the old solver doesn't infer the best return type here
         CHECK_EQ("((boolean | number)?) -> boolean | number", toString(requireType("f")));
@@ -1078,7 +1080,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "assert_removes_falsy_types3")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "assert_removes_falsy_types_even_from_type_pack_tail_but_only_for_the_first_type")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1093,7 +1095,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "assert_removes_falsy_types_even_from_type_pa
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "assert_returns_false_and_string_iff_it_knows_the_first_argument_cannot_be_truthy")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114134 - egraph simplification
         return;
@@ -1128,7 +1130,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_freeze_is_generic")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Key 'b' not found in table '{ a: number }'" == toString(result.errors[0]));
     else
         CHECK_EQ("Key 'b' not found in table '{| a: number |}'", toString(result.errors[0]));
@@ -1138,7 +1140,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_freeze_is_generic")
     CHECK_EQ("string", toString(requireType("b")));
     CHECK_EQ("boolean", toString(requireType("c")));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("any", toString(requireType("d")));
     else
         CHECK_EQ("*error-type*", toString(requireType("d")));
@@ -1147,7 +1149,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_freeze_is_generic")
 TEST_CASE_FIXTURE(BuiltinsFixture, "set_metatable_needs_arguments")
 {
     // In the new solver, nil can certainly be used where a generic is required, so all generic parameters are optional.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a = {b=setmetatable}

tests/TypeInfer.classes.test.cpp

@@ -13,7 +13,7 @@
 using namespace Luau;
 using std::nullopt;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("TypeInferClasses");
 
@@ -128,7 +128,7 @@ TEST_CASE_FIXTURE(ClassFixture, "we_can_infer_that_a_parameter_must_be_a_particu
 
 TEST_CASE_FIXTURE(ClassFixture, "we_can_report_when_someone_is_trying_to_use_a_table_rather_than_a_class")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function makeClone(o)
@@ -156,7 +156,7 @@ TEST_CASE_FIXTURE(ClassFixture, "we_can_report_when_someone_is_trying_to_use_a_t
 
 TEST_CASE_FIXTURE(ClassFixture, "we_can_report_when_someone_is_trying_to_use_a_table_rather_than_a_class_using_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function makeClone(o)
@@ -235,7 +235,7 @@ TEST_CASE_FIXTURE(ClassFixture, "can_assign_to_prop_of_base_class_using_string")
 TEST_CASE_FIXTURE(ClassFixture, "cannot_unify_class_instance_with_primitive")
 {
     // This is allowed in the new solver
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local v = Vector2.New(0, 5)
@@ -397,7 +397,7 @@ TEST_CASE_FIXTURE(ClassFixture, "table_class_unification_reports_sane_errors_for
         foo(a)
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK("Type 'Vector2' could not be converted into '{ Y: number, w: number, x: number }'" == toString(result.errors[0]));
@@ -454,7 +454,7 @@ b(a)
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("Type 'number' could not be converted into 'string'" == toString(result.errors.at(0)));
     }
@@ -472,7 +472,7 @@ Type 'number' could not be converted into 'string')";
 TEST_CASE_FIXTURE(ClassFixture, "class_type_mismatch_with_name_conflict")
 {
     // CLI-116433
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local i = ChildClass.New()
@@ -545,7 +545,7 @@ local b: B = a
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == "Type 'A' could not be converted into 'B'; at [read \"x\"], ChildClass is not exactly BaseClass");
     else
     {
@@ -559,7 +559,7 @@ Type 'ChildClass' could not be converted into 'BaseClass' in an invariant contex
 
 TEST_CASE_FIXTURE(ClassFixture, "optional_class_casts_work_in_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type A = { x: ChildClass }
@@ -664,7 +664,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
             local y = x[true]
         )");
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK(
                 "Type 'boolean' could not be converted into 'number | string'" == toString(result.errors.at(0))
             );
@@ -679,7 +679,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
             x[true] = 42
         )");
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK(
                 "Type 'boolean' could not be converted into 'number | string'" == toString(result.errors.at(0))
             );
@@ -696,7 +696,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
             x.key = "string value"
         )");
 
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
         {
             // Disabled for now.  CLI-115686
         }
@@ -724,7 +724,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
             local x : IndexableNumericKeyClass
             x["key"] = 1
         )");
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK_EQ(toString(result.errors.at(0)), "Key 'key' not found in class 'IndexableNumericKeyClass'");
         else
             CHECK_EQ(toString(result.errors.at(0)), "Type 'string' could not be converted into 'number'");
@@ -749,7 +749,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
             local x : IndexableNumericKeyClass
             local y = x["key"]
         )");
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK(toString(result.errors.at(0)) == "Key 'key' not found in class 'IndexableNumericKeyClass'");
         else
             CHECK_EQ(toString(result.errors.at(0)), "Type 'string' could not be converted into 'number'");
@@ -766,7 +766,7 @@ TEST_CASE_FIXTURE(ClassFixture, "indexable_classes")
 
 TEST_CASE_FIXTURE(Fixture, "read_write_class_properties")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     TypeArena& arena = frontend.globals.globalTypes;
 

tests/TypeInfer.functions.test.cpp

@@ -17,7 +17,7 @@
 using namespace Luau;
 
 LUAU_FASTFLAG(LuauInstantiateInSubtyping);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTINT(LuauTarjanChildLimit);
 
 LUAU_DYNAMIC_FASTFLAG(LuauImproveNonFunctionCallError)
@@ -79,7 +79,7 @@ TEST_CASE_FIXTURE(Fixture, "check_function_bodies")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         const TypePackMismatch* tm = get<TypePackMismatch>(result.errors[0]);
         REQUIRE(tm);
@@ -238,7 +238,7 @@ TEST_CASE_FIXTURE(Fixture, "list_only_alternative_overloads_that_match_argument_
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         GenericError* g = get<GenericError>(result.errors[0]);
         REQUIRE(g);
@@ -255,7 +255,7 @@ TEST_CASE_FIXTURE(Fixture, "list_only_alternative_overloads_that_match_argument_
     ExtraInformation* ei = get<ExtraInformation>(result.errors[1]);
     REQUIRE(ei);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Available overloads: (number) -> number; (number) -> string; and (number, number) -> number" == ei->message);
     else
         CHECK_EQ("Other overloads are also not viable: (number) -> string", ei->message);
@@ -312,7 +312,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_return_type_from_selected_overload")
 TEST_CASE_FIXTURE(Fixture, "too_many_arguments")
 {
     // This is not part of the new non-strict specification currently.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -480,7 +480,7 @@ TEST_CASE_FIXTURE(Fixture, "another_higher_order_function")
 
 TEST_CASE_FIXTURE(Fixture, "another_other_higher_order_function")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CheckResult result = check(R"(
             local function f(d)
@@ -604,7 +604,7 @@ TEST_CASE_FIXTURE(Fixture, "duplicate_functions_allowed_in_nonstrict")
 TEST_CASE_FIXTURE(Fixture, "duplicate_functions_with_different_signatures_not_allowed_in_nonstrict")
 {
     // This is not part of the spec for the new non-strict mode currently.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -883,7 +883,7 @@ TEST_CASE_FIXTURE(Fixture, "another_indirect_function_case_where_it_is_ok_to_pro
 TEST_CASE_FIXTURE(Fixture, "report_exiting_without_return_nonstrict")
 {
     // new non-strict mode spec does not include this error yet.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -1009,7 +1009,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "calling_function_with_anytypepack_doesnt_lea
     opts.exhaustive = true;
     opts.maxTableLength = 0;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{string}", toString(requireType("tab"), opts));
     else
         CHECK_EQ("{any}", toString(requireType("tab"), opts));
@@ -1018,7 +1018,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "calling_function_with_anytypepack_doesnt_lea
 TEST_CASE_FIXTURE(Fixture, "too_many_return_values")
 {
     // FIXME: CLI-116157 variadic and generic type packs seem to be interacting incorrectly.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -1042,7 +1042,7 @@ TEST_CASE_FIXTURE(Fixture, "too_many_return_values")
 TEST_CASE_FIXTURE(Fixture, "too_many_return_values_in_parentheses")
 {
     // FIXME: CLI-116157 variadic and generic type packs seem to be interacting incorrectly.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -1066,7 +1066,7 @@ TEST_CASE_FIXTURE(Fixture, "too_many_return_values_in_parentheses")
 TEST_CASE_FIXTURE(Fixture, "too_many_return_values_no_function")
 {
     // FIXME: CLI-116157 variadic and generic type packs seem to be interacting incorrectly.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -1108,7 +1108,7 @@ TEST_CASE_FIXTURE(Fixture, "function_does_not_return_enough_values")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 
@@ -1148,7 +1148,7 @@ TEST_CASE_FIXTURE(Fixture, "function_cast_error_uses_correct_language")
     REQUIRE(tm1);
 
     CHECK_EQ("(string) -> number", toString(tm1->wantedType));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(unknown, unknown) -> number", toString(tm1->givenType));
     else
         CHECK_EQ("(string, *error-type*) -> number", toString(tm1->givenType));
@@ -1157,7 +1157,7 @@ TEST_CASE_FIXTURE(Fixture, "function_cast_error_uses_correct_language")
     REQUIRE(tm2);
 
     CHECK_EQ("(number, number) -> (number, number)", toString(tm2->wantedType));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(unknown, unknown) -> number", toString(tm1->givenType));
     else
         CHECK_EQ("(string, *error-type*) -> number", toString(tm2->givenType));
@@ -1177,7 +1177,7 @@ TEST_CASE_FIXTURE(Fixture, "no_lossy_function_type")
 
     LUAU_REQUIRE_NO_ERRORS(result);
     TypeId type = requireTypeAtPosition(Position(6, 14));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(unknown, number, number) -> number", toString(type));
     else
         CHECK_EQ("(tbl, number, number) -> number", toString(type));
@@ -1224,7 +1224,7 @@ TEST_CASE_FIXTURE(Fixture, "return_type_by_overload")
     LUAU_REQUIRE_ERRORS(result);
     CHECK_EQ("string", toString(requireType("x")));
     // the new solver does not currently "favor" arity-matching overloads when the call itself is ill-typed.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("string", toString(requireType("y")));
     else
         CHECK_EQ("number", toString(requireType("y")));
@@ -1235,7 +1235,7 @@ TEST_CASE_FIXTURE(Fixture, "return_type_by_overload")
 TEST_CASE_FIXTURE(BuiltinsFixture, "infer_anonymous_function_arguments")
 {
     // FIXME: CLI-116133 bidirectional type inference needs to push expected types in for higher-order function calls
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     // Simple direct arg to arg propagation
     CheckResult result = check(R"(
@@ -1354,7 +1354,7 @@ f(function(x) return x * 2 end)
 TEST_CASE_FIXTURE(BuiltinsFixture, "infer_generic_function_function_argument")
 {
     // FIXME: CLI-116133 bidirectional type inference needs to push expected types in for higher-order function calls
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local function sum<a>(x: a, y: a, f: (a, a) -> a) return f(x, y) end
@@ -1385,7 +1385,7 @@ local r = foldl(a, {s=0,c=0}, function(a, b) return {s = a.s + b, c = a.c + 1} e
 TEST_CASE_FIXTURE(Fixture, "infer_generic_function_function_argument_overloaded")
 {
     // FIXME: CLI-116133 bidirectional type inference needs to push expected types in for higher-order function calls
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local function g1<T>(a: T, f: (T) -> T) return f(a) end
@@ -1452,7 +1452,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "variadic_any_is_compatible_with_a_generic_Ty
 TEST_CASE_FIXTURE(Fixture, "infer_anonymous_function_arguments_outside_call")
 {
     // FIXME: CLI-116133 bidirectional type inference needs to push expected types in for higher-order function calls
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type Table = { x: number, y: number }
@@ -1486,7 +1486,7 @@ end
     )");
 
     // `h` regresses in the new solver, the return type is not being pushed into the body.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_ERROR_COUNT(1, result);
     else
         LUAU_REQUIRE_NO_ERRORS(result);
@@ -1495,7 +1495,7 @@ end
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_arg_count")
 {
     // FIXME: CLI-116111 test disabled until type path stringification is improved
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type A = (number, number) -> string
@@ -1518,7 +1518,7 @@ caused by:
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_arg")
 {
     // FIXME: CLI-116111 test disabled until type path stringification is improved
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type A = (number, number) -> string
@@ -1542,7 +1542,7 @@ Type 'string' could not be converted into 'number')";
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_ret_count")
 {
     // FIXME: CLI-116111 test disabled until type path stringification is improved
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type A = (number, number) -> (number)
@@ -1565,7 +1565,7 @@ caused by:
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_ret")
 {
     // FIXME: CLI-116111 test disabled until type path stringification is improved
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type A = (number, number) -> string
@@ -1589,7 +1589,7 @@ Type 'string' could not be converted into 'number')";
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_ret_mult")
 {
     // FIXME: CLI-116111 test disabled until type path stringification is improved
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type A = (number, number) -> (number, string)
@@ -1670,7 +1670,7 @@ t.f = function(x)
 end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(
@@ -1720,7 +1720,7 @@ TEST_CASE_FIXTURE(Fixture, "inferred_higher_order_functions_are_quantified_at_th
 {
     // This test regresses in the new solver, but is sort of nonsensical insofar as `foo` is known to be `nil`, so it's "right" to not be able to call
     // it.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local foo
@@ -1748,7 +1748,7 @@ t.f = function(x)
 end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK_EQ(
@@ -1789,7 +1789,7 @@ TEST_CASE_FIXTURE(Fixture, "strict_mode_ok_with_missing_arguments")
 TEST_CASE_FIXTURE(Fixture, "function_statement_sealed_table_assignment_through_indexer")
 {
     // FIXME: CLI-116122 bug where `t:b` does not check against the type from the indexer annotation on `t`.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local t: {[string]: () -> number} = {}
@@ -1834,7 +1834,7 @@ TEST_CASE_FIXTURE(Fixture, "too_few_arguments_variadic")
 TEST_CASE_FIXTURE(Fixture, "too_few_arguments_variadic_generic")
 {
     // FIXME: CLI-116157 variadic and generic type packs seem to be interacting incorrectly.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 function test(a: number, b: string, ...)
@@ -1862,7 +1862,7 @@ wrapper(test)
 TEST_CASE_FIXTURE(BuiltinsFixture, "too_few_arguments_variadic_generic2")
 {
     // FIXME: CLI-116157 variadic and generic type packs seem to be interacting incorrectly.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 function test(a: number, b: string, ...)
@@ -1903,7 +1903,7 @@ TEST_CASE_FIXTURE(Fixture, "occurs_check_failure_in_function_return_type")
 TEST_CASE_FIXTURE(Fixture, "free_is_not_bound_to_unknown")
 {
     // This test only makes sense for the old solver
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1937,7 +1937,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_infer_parameter_types_for_functions_from_their_
     LUAU_REQUIRE_NO_ERRORS(result);
 
     CHECK_EQ("<a>(a) -> a", toString(requireType("f")));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("({ read p: { read q: unknown } }) -> ~(false?)?", toString(requireType("g")));
     else
         CHECK_EQ("({+ p: {+ q: nil +} +}) -> nil", toString(requireType("g")));
@@ -1985,7 +1985,7 @@ u.b().foo()
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(9, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // These improvements to the error messages are currently regressed in the new type solver.
         CHECK_EQ(toString(result.errors[0]), "Argument count mismatch. Function expects 1 argument, but none are specified");
@@ -2016,7 +2016,7 @@ u.b().foo()
 TEST_CASE_FIXTURE(BuiltinsFixture, "improved_function_arg_mismatch_error_nonstrict")
 {
     // This behavior is not part of the current specification of the new type solver.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -2031,7 +2031,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "improved_function_arg_mismatch_error_nonstri
 TEST_CASE_FIXTURE(Fixture, "luau_subtyping_is_np_hard")
 {
     // The case that _should_ succeed here (`z = x`) does not currently in the new solver.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -2153,7 +2153,7 @@ end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "dont_assert_when_the_tarjan_limit_is_exceeded_during_generalization")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
     ScopedFastInt sfi{FInt::LuauTarjanChildLimit, 1};
 
     CheckResult result = check(R"(
@@ -2199,7 +2199,7 @@ TEST_CASE_FIXTURE(Fixture, "instantiated_type_packs_must_have_a_non_null_scope")
 
 TEST_CASE_FIXTURE(Fixture, "inner_frees_become_generic_in_dcr")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -2229,7 +2229,7 @@ TEST_CASE_FIXTURE(Fixture, "function_exprs_are_generalized_at_signature_scope_no
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(requireType("foo")) == "((unknown) -> nil)?");
     else
     {
@@ -2248,7 +2248,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "param_1_and_2_both_takes_the_same_generic_bu
         local ret: number = foo(vec2, { x = 5 })
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 
@@ -2312,7 +2312,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "param_1_and_2_both_takes_the_same_generic_bu
         local z: boolean = f(5, "five")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 
@@ -2342,14 +2342,14 @@ TEST_CASE_FIXTURE(Fixture, "attempt_to_call_an_intersection_of_tables")
 
     if (DFFlag::LuauImproveNonFunctionCallError)
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK_EQ(toString(result.errors[0]), "Cannot call a value of type { x: number } & { y: string }");
         else
             CHECK_EQ(toString(result.errors[0]), "Cannot call a value of type {| x: number |}");
     }
     else
     {
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK_EQ(toString(result.errors[0]), "Cannot call non-function { x: number } & { y: string }");
         else
             CHECK_EQ(toString(result.errors[0]), "Cannot call non-function {| x: number |}");
@@ -2373,7 +2373,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "attempt_to_call_an_intersection_of_tables_wi
 
 TEST_CASE_FIXTURE(Fixture, "generic_packs_are_not_variadic")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function apply<a, b..., c...>(f: (a, b...) -> c..., x: a)
@@ -2409,7 +2409,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "num_is_solved_before_num_or_str")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == "Type pack 'string' could not be converted into 'number'; at [0], string is not a subtype of number");
     else
         CHECK_EQ("Type 'string' could not be converted into 'number'", toString(result.errors[0]));
@@ -2434,7 +2434,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "num_is_solved_after_num_or_str")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == "Type pack 'string' could not be converted into 'number'; at [0], string is not a subtype of number");
     else
         CHECK_EQ("Type 'string' could not be converted into 'number'", toString(result.errors[0]));
@@ -2483,7 +2483,7 @@ a = function(a, b) return a + b end
 TEST_CASE_FIXTURE(BuiltinsFixture, "simple_unannotated_mutual_recursion")
 {
     // CLI-117118 - TypeInferFunctions.simple_unannotated_mutual_recursion relies on unstable assertions to pass.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
 function even(n)
@@ -2505,7 +2505,7 @@ function odd(n)
 end
 )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(5, result);
         // CLI-117117 Constraint solving is incomplete inTypeInferFunctions.simple_unannotated_mutual_recursion
@@ -2565,7 +2565,7 @@ end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "tf_suggest_return_type")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
 function fib(n)
@@ -2583,7 +2583,7 @@ end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "tf_suggest_arg_type")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
 function fib(n, u)
@@ -2602,7 +2602,7 @@ end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "tf_suggest_arg_type_2")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     // Make sure the error types are cloned to module interface
@@ -2655,7 +2655,7 @@ TEST_CASE_FIXTURE(Fixture, "bidirectional_checking_of_callback_property")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         auto tm = get<TypeMismatch>(result.errors[0]);
         REQUIRE(tm);
@@ -2727,7 +2727,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_infer_overloaded_functions")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(t1) -> () where t1 = { read FindFirstChild: (t1, string) -> (...unknown) }" == toString(requireType("getR6Attachments")));
     else
         CHECK("<a...>(t1) -> () where t1 = {+ FindFirstChild: (t1, string) -> (a...) +}" == toString(requireType("getR6Attachments")));
@@ -2891,7 +2891,7 @@ TEST_CASE_FIXTURE(Fixture, "unifier_should_not_bind_free_types")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // The new solver should ideally be able to do better here, but this is no worse than the old solver.
 

tests/TypeInfer.generics.test.cpp

@@ -10,7 +10,7 @@
 #include "doctest.h"
 
 LUAU_FASTFLAG(LuauInstantiateInSubtyping);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 using namespace Luau;
 
@@ -70,7 +70,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "unions_and_generics")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("number | {number}", toString(requireType("res")));
     else // in the old solver, this just totally falls apart
         CHECK_EQ("a", toString(requireType("res")));
@@ -142,7 +142,7 @@ TEST_CASE_FIXTURE(Fixture, "properties_can_be_polytypes")
 
 TEST_CASE_FIXTURE(Fixture, "properties_can_be_instantiated_polytypes")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t: { m: (number)->number } = { m = function(x:number) return x+1 end }
@@ -198,7 +198,7 @@ TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions")
 
 TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions_unannotated")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -220,7 +220,7 @@ TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions_unannotated")
 
 TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions_errors")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -260,7 +260,7 @@ TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions_errors")
 
 TEST_CASE_FIXTURE(Fixture, "generic_functions_in_types_old_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type T = { id: <a>(a) -> a }
@@ -273,7 +273,7 @@ TEST_CASE_FIXTURE(Fixture, "generic_functions_in_types_old_solver")
 
 TEST_CASE_FIXTURE(Fixture, "generic_functions_in_types_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type T = { read id: <a>(a) -> a }
@@ -286,7 +286,7 @@ TEST_CASE_FIXTURE(Fixture, "generic_functions_in_types_new_solver")
 
 TEST_CASE_FIXTURE(Fixture, "generic_factories")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type T<a> = { id: (a) -> a }
@@ -309,7 +309,7 @@ TEST_CASE_FIXTURE(Fixture, "generic_factories")
 
 TEST_CASE_FIXTURE(Fixture, "factories_of_generics")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type T = { id: <a>(a) -> a }
@@ -466,7 +466,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_leak_generic_types")
         local b: boolean = f(true)
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -489,7 +489,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_leak_inferred_generic_types")
             local y: number = id(37)
         end
     )");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -648,7 +648,7 @@ TEST_CASE_FIXTURE(Fixture, "generic_type_pack_parentheses")
 
     // This should really error, but the error from the old solver is wrong.
     // `a...` is a generic type pack, and we don't know that it will be non-empty, thus this code may not work.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_ERROR_COUNT(1, result);
@@ -669,7 +669,7 @@ TEST_CASE_FIXTURE(Fixture, "better_mismatch_error_messages")
     SwappedGenericTypeParameter* fErr;
     SwappedGenericTypeParameter* gErr;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(3, result);
         // The first error here is an unknown symbol that is redundant with the `fErr`.
@@ -774,7 +774,7 @@ return exports
 
 TEST_CASE_FIXTURE(Fixture, "instantiated_function_argument_names_old_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f<T, U...>(a: T, ...: U...) end
@@ -793,7 +793,7 @@ TEST_CASE_FIXTURE(Fixture, "instantiated_function_argument_names_old_solver")
 
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_generic_types")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type C = () -> ()
@@ -810,7 +810,7 @@ local d: D = c
 
 TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_generic_pack")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 type C = () -> ()
@@ -866,7 +866,7 @@ y.a.c = y
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(
             toString(result.errors.at(0)) ==
             R"(Type '{ a: { c: nil, d: number }, b: number }' could not be converted into 'T<number>'; type { a: { c: nil, d: number }, b: number }[read "a"][read "c"] (nil) is not exactly T<number>[read "a"][read "c"][0] (T<number>))"
@@ -886,7 +886,7 @@ Type 'number' could not be converted into 'string' in an invariant context)";
 
 TEST_CASE_FIXTURE(Fixture, "generic_type_pack_unification1")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -906,7 +906,7 @@ local TheDispatcher: Dispatcher = {
 
 TEST_CASE_FIXTURE(Fixture, "generic_type_pack_unification2")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -926,7 +926,7 @@ local TheDispatcher: Dispatcher = {
 
 TEST_CASE_FIXTURE(Fixture, "generic_type_pack_unification3")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -946,7 +946,7 @@ local TheDispatcher: Dispatcher = {
 
 TEST_CASE_FIXTURE(Fixture, "generic_argument_count_too_few")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 function test(a: number)
@@ -965,7 +965,7 @@ wrapper(test)
 
 TEST_CASE_FIXTURE(Fixture, "generic_argument_count_too_many")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 function test2(a: number, b: string)
@@ -1163,7 +1163,7 @@ local a: Self<Table>
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireType("a")), "Table<Table>");
     else
         CHECK_EQ(toString(requireType("a")), "Table");
@@ -1182,7 +1182,7 @@ TEST_CASE_FIXTURE(Fixture, "no_stack_overflow_from_quantifying")
 
     std::optional<TypeId> t0 = lookupType("t0");
     REQUIRE(t0);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("any", toString(*t0));
     else
         CHECK_EQ("*error-type*", toString(*t0));
@@ -1202,7 +1202,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "infer_generic_function_function_argument")
 {
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CheckResult result = check(R"(
             local function sum<a>(x: a, y: a, f: (a, a) -> add<a>)
@@ -1259,7 +1259,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "infer_generic_function_function_argument_3")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         REQUIRE_EQ("{ c: number, s: number } | { c: number, s: number }", toString(requireType("r")));
     else
         REQUIRE_EQ("{ c: number, s: number }", toString(requireType("r")));
@@ -1301,7 +1301,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "do_not_infer_generic_functions")
 
     CheckResult result;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         result = check(R"(
             local function sum<a>(x: a, y: a, f: (a, a) -> a) return f(x, y) end
@@ -1421,7 +1421,7 @@ TEST_CASE_FIXTURE(Fixture, "apply_type_function_nested_generics3")
 
 TEST_CASE_FIXTURE(Fixture, "quantify_functions_even_if_they_have_an_explicit_generic")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function foo<X>(f, x: X)
@@ -1434,7 +1434,7 @@ TEST_CASE_FIXTURE(Fixture, "quantify_functions_even_if_they_have_an_explicit_gen
 
 TEST_CASE_FIXTURE(Fixture, "do_not_always_instantiate_generic_intersection_types")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -1470,7 +1470,7 @@ end
 TEST_CASE_FIXTURE(BuiltinsFixture, "higher_rank_polymorphism_should_not_accept_instantiated_arguments")
 {
     ScopedFastFlag sffs[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
         {FFlag::LuauInstantiateInSubtyping, true},
     };
 
@@ -1537,9 +1537,9 @@ TEST_CASE_FIXTURE(Fixture, "missing_generic_type_parameter")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "generic_type_functions_work_in_subtyping")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(

tests/TypeInfer.intersectionTypes.test.cpp

@@ -9,7 +9,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("IntersectionTypes");
 
@@ -172,7 +172,7 @@ TEST_CASE_FIXTURE(Fixture, "index_on_an_intersection_type_with_property_guarante
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(A & B) -> { y: number }" == toString(requireType("f")));
     else
         CHECK("(A & B) -> {| y: number |} & {| y: number |}" == toString(requireType("f")));
@@ -191,7 +191,7 @@ TEST_CASE_FIXTURE(Fixture, "index_on_an_intersection_type_works_at_arbitrary_dep
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(A & B) -> string", toString(requireType("f")));
     else
         CHECK_EQ("(A & B) -> string & string", toString(requireType("f")));
@@ -210,7 +210,7 @@ TEST_CASE_FIXTURE(Fixture, "index_on_an_intersection_type_with_mixed_types")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(A & B) -> never", toString(requireType("f")));
     else
         CHECK_EQ("(A & B) -> number & string", toString(requireType("f")));
@@ -333,7 +333,7 @@ TEST_CASE_FIXTURE(Fixture, "table_intersection_write_sealed")
 TEST_CASE_FIXTURE(Fixture, "table_intersection_write_sealed_indirect")
 {
     ScopedFastFlag dcr{
-        FFlag::DebugLuauDeferredConstraintResolution, false
+        FFlag::LuauSolverV2, false
     }; // CLI-116476 Subtyping between type alias and an equivalent but not named type isn't working.
     CheckResult result = check(R"(
         type X = { x: (number) -> number }
@@ -348,7 +348,7 @@ TEST_CASE_FIXTURE(Fixture, "table_intersection_write_sealed_indirect")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(toString(result.errors[0]), "Cannot add property 'z' to table 'X & Y'");
@@ -372,7 +372,7 @@ caused by:
 
 TEST_CASE_FIXTURE(Fixture, "table_write_sealed_indirect")
 {
-    ScopedFastFlag dcr{FFlag::DebugLuauDeferredConstraintResolution, false}; // CLI-
+    ScopedFastFlag dcr{FFlag::LuauSolverV2, false}; // CLI-
     // After normalization, previous 'table_intersection_write_sealed_indirect' is identical to this one
     CheckResult result = check(R"(
     type XY = { x: (number) -> number, y: (string) -> string }
@@ -430,7 +430,7 @@ Type 'number' could not be converted into 'X')";
         R"(Type 'number' could not be converted into 'X & Y & Z'; type number (number) is not a subtype of X & Y & Z[0] (X)
 	type number (number) is not a subtype of X & Y & Z[1] (Y)
 	type number (number) is not a subtype of X & Y & Z[2] (Z))";
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(dcrExprected, toString(result.errors[0]));
     else
         CHECK_EQ(expected, toString(result.errors[0]));
@@ -450,7 +450,7 @@ end
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             R"(Type pack 'X & Y & Z' could not be converted into 'number'; type X & Y & Z[0][0] (X) is not a subtype of number[0] (number)
@@ -503,7 +503,7 @@ TEST_CASE_FIXTURE(Fixture, "intersect_bool_and_false")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             R"(Type 'boolean & false' could not be converted into 'true'; type boolean & false[0] (boolean) is not a subtype of true (true)
@@ -528,7 +528,7 @@ TEST_CASE_FIXTURE(Fixture, "intersect_false_and_bool_and_false")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
     // TODO: odd stringification of `false & (boolean & false)`.)
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(
             R"(Type 'boolean & false & false' could not be converted into 'true'; type boolean & false & false[0] (false) is not a subtype of true (true)
 	type boolean & false & false[1] (boolean) is not a subtype of true (true)
@@ -550,7 +550,7 @@ TEST_CASE_FIXTURE(Fixture, "intersect_saturate_overloaded_functions")
             local z : (number) -> number = x -- Not OK
         end
     )");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         const std::string expected1 = R"(Type
@@ -582,7 +582,7 @@ could not be converted into
 TEST_CASE_FIXTURE(Fixture, "union_saturate_overloaded_functions")
 {
     ScopedFastFlag dcr{
-        FFlag::DebugLuauDeferredConstraintResolution, false
+        FFlag::LuauSolverV2, false
     }; // CLI-116474 Semantic subtyping of assignments needs to decide how to interpret intersections of functions
     CheckResult result = check(R"(
         function f(x: ((number) -> number) & ((string) -> string))
@@ -610,7 +610,7 @@ TEST_CASE_FIXTURE(Fixture, "intersection_of_tables")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
     const std::string expected =
-        (FFlag::DebugLuauDeferredConstraintResolution)
+        (FFlag::LuauSolverV2)
             ? R"(Type '{ p: number?, q: number?, r: number? } & { p: number?, q: string? }' could not be converted into '{ p: nil }'; type { p: number?, q: number?, r: number? } & { p: number?, q: string? }[0][read "p"][0] (number) is not exactly { p: nil }[read "p"] (nil)
 	type { p: number?, q: number?, r: number? } & { p: number?, q: string? }[1][read "p"][0] (number) is not exactly { p: nil }[read "p"] (nil))"
             :
@@ -630,7 +630,7 @@ TEST_CASE_FIXTURE(Fixture, "intersection_of_tables_with_top_properties")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK_EQ(
@@ -678,7 +678,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_functions_returning_intersections")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(
@@ -726,7 +726,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_functions_mentioning_generic")
             end
         end
     )");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(0, result);
     }
@@ -753,7 +753,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_functions_mentioning_generics")
     )");
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -778,7 +778,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_functions_mentioning_generic_packs")
             end
         end
     )");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(
@@ -812,7 +812,7 @@ could not be converted into
 TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_unknown_result")
 {
     ScopedFastFlag dcr{
-        FFlag::DebugLuauDeferredConstraintResolution, false
+        FFlag::LuauSolverV2, false
     }; // CLI-116474 Semantic subtyping of assignments needs to decide how to interpret intersections of functions
     CheckResult result = check(R"(
         function f<a...,b...>()
@@ -834,7 +834,7 @@ could not be converted into
 TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_unknown_arguments")
 {
     ScopedFastFlag dcr{
-        FFlag::DebugLuauDeferredConstraintResolution, false
+        FFlag::LuauSolverV2, false
     }; // CLI-116474 Semantic subtyping of assignments needs to decide how to interpret intersections of functions
     CheckResult result = check(R"(
         function f<a...,b...>()
@@ -864,7 +864,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_never_result")
     end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         CHECK_EQ(
@@ -907,7 +907,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_never_arguments")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
         const std::string expected1 = R"(Type
@@ -940,7 +940,7 @@ could not be converted into
 TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_overlapping_results_and_variadics")
 {
     ScopedFastFlag dcr{
-        FFlag::DebugLuauDeferredConstraintResolution, false
+        FFlag::LuauSolverV2, false
     }; // CLI-116474 Semantic subtyping of assignments needs to decide how to interpret intersections of functions
     CheckResult result = check(R"(
         function f(x : ((string?) -> (string | number)) & ((number?) -> ...number))
@@ -968,7 +968,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_weird_typepacks_1")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -993,7 +993,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_weird_typepacks_2")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -1018,7 +1018,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_weird_typepacks_3")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -1045,7 +1045,7 @@ TEST_CASE_FIXTURE(Fixture, "overloadeded_functions_with_weird_typepacks_4")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             R"(Type
@@ -1071,10 +1071,10 @@ could not be converted into
 TEST_CASE_FIXTURE(BuiltinsFixture, "intersect_metatables")
 {
     // CLI-117121 - Intersection of types are not compatible with the equivalent alias
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CheckResult result = check(R"(
             function f(a: string?, b: string?)
@@ -1164,7 +1164,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "intersect_metatables_with_properties")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "intersect_metatable_with_table")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CheckResult result = check(R"(
             local x = setmetatable({ a = 5 }, { p = 5 })
@@ -1230,7 +1230,7 @@ TEST_CASE_FIXTURE(Fixture, "CLI-44817")
 
 TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_intersection_types")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1247,7 +1247,7 @@ TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_intersection_types")
 
 TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_intersection_types_2")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1293,7 +1293,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "index_property_table_intersection_2")
 
 TEST_CASE_FIXTURE(Fixture, "cli_80596_simplify_degenerate_intersections")
 {
-    ScopedFastFlag dcr{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag dcr{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type A = {
@@ -1316,7 +1316,7 @@ TEST_CASE_FIXTURE(Fixture, "cli_80596_simplify_degenerate_intersections")
 
 TEST_CASE_FIXTURE(Fixture, "cli_80596_simplify_more_realistic_intersections")
 {
-    ScopedFastFlag dcr{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag dcr{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type A = {

tests/TypeInfer.loops.test.cpp

@@ -14,7 +14,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauOkWithIteratingOverTableProperties)
 
 LUAU_DYNAMIC_FASTFLAG(LuauImproveNonFunctionCallError)
@@ -32,7 +32,7 @@ TEST_CASE_FIXTURE(Fixture, "for_loop")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // Luau cannot see that the loop must always run at least once, so we
         // think that q could be nil.
@@ -45,10 +45,10 @@ TEST_CASE_FIXTURE(Fixture, "for_loop")
 TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_no_table_passed")
 {
     // This test may block CI if forced to run outside of DCR.
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
     CheckResult result = check(R"(
 
 type Iterable = typeof(setmetatable(
@@ -72,7 +72,7 @@ for a, b in t do end
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_regression_issue_69967")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -93,7 +93,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_regression_issue_69967")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_regression_issue_69967_alt")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -114,7 +114,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_regression_issue_69967_alt")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // It's possible for the loop body to execute 0 times.
         CHECK("number?" == toString(requireType("x")));
@@ -140,7 +140,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("number?" == toString(requireType("n")));
         CHECK("string?" == toString(requireType("s")));
@@ -155,7 +155,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop")
 TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_with_next")
 {
     // CLI-116494 The generics K and V are leaking out of the next() function somehow.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local n
@@ -222,7 +222,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_with_just_one_iterator_is_ok")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_with_zero_iterators_dcr")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function no_iter() end
@@ -267,7 +267,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_on_error")
     LUAU_REQUIRE_ERROR_COUNT(2, result);
 
     TypeId p = requireType("p");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("*error-type*?", toString(p));
     else
         CHECK_EQ("*error-type*", toString(p));
@@ -276,7 +276,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_on_error")
 TEST_CASE_FIXTURE(Fixture, "for_in_loop_on_non_function")
 {
     // We report a spuriouus duplicate error here.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local bad_iter = 5
@@ -293,7 +293,7 @@ TEST_CASE_FIXTURE(Fixture, "for_in_loop_on_non_function")
 TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_error_on_factory_not_returning_the_right_amount_of_values")
 {
     // Spurious duplicate errors
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function hasDivisors(value: number, table)
@@ -345,7 +345,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_error_on_factory_not_returning_t
 TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_error_on_iterator_requiring_args_but_none_given")
 {
     // CLI-116496
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function prime_iter(state, index)
@@ -419,7 +419,7 @@ TEST_CASE_FIXTURE(Fixture, "while_loop")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("number?" == toString(requireType("i")));
     else
         CHECK_EQ(*builtinTypes->numberType, *requireType("i"));
@@ -436,7 +436,7 @@ TEST_CASE_FIXTURE(Fixture, "repeat_loop")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("string?" == toString(requireType("i")));
     else
         CHECK_EQ(*builtinTypes->stringType, *requireType("i"));
@@ -478,7 +478,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "varlist_declared_by_for_in_loop_should_be_fr
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         auto err = get<TypeMismatch>(result.errors[0]);
@@ -535,7 +535,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "properly_infer_iteratee_is_a_free_table")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // In the new solver, we infer iter: unknown and so we warn on use of its properties.
         LUAU_REQUIRE_ERROR_COUNT(1, result);
@@ -585,7 +585,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "ipairs_produces_integral_indices")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("number?" == toString(requireType("key")));
     else
         REQUIRE_EQ("number", toString(requireType("key")));
@@ -696,7 +696,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "unreachable_code_after_infinite_loop")
 TEST_CASE_FIXTURE(BuiltinsFixture, "loop_typecheck_crash_on_empty_optional")
 {
     // CLI-116498 Sometimes you can iterate over tables with no indexers.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     ScopedFastFlag sff{FFlag::LuauOkWithIteratingOverTableProperties, true};
@@ -753,7 +753,7 @@ TEST_CASE_FIXTURE(Fixture, "loop_iter_basic")
 
     // The old solver just infers the wrong type here.
     // The right type for `key` is `number?`
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         TypeId keyTy = requireType("key");
         CHECK("number?" == toString(keyTy));
@@ -765,7 +765,7 @@ TEST_CASE_FIXTURE(Fixture, "loop_iter_basic")
 TEST_CASE_FIXTURE(Fixture, "loop_iter_trailing_nil")
 {
     // CLI-116498 Sometimes you can iterate over tables with no indexers.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t: {string} = {}
@@ -783,7 +783,7 @@ TEST_CASE_FIXTURE(Fixture, "loop_iter_no_indexer_strict")
 {
     // CLI-116498 Sometimes you can iterate over tables with no indexers.
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
         {FFlag::LuauOkWithIteratingOverTableProperties, true}
     };
 
@@ -810,7 +810,7 @@ TEST_CASE_FIXTURE(Fixture, "loop_iter_no_indexer_nonstrict")
 TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_nil")
 {
     // CLI-116499 Free types persisting until typechecking time.
-    if (1 || !FFlag::DebugLuauDeferredConstraintResolution)
+    if (1 || !FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -826,7 +826,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_nil")
 TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_not_enough_returns")
 {
     // CLI-116500
-    if (1 || !FFlag::DebugLuauDeferredConstraintResolution)
+    if (1 || !FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -848,7 +848,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_not_enough_returns")
 TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_ok")
 {
     // CLI-116500
-    if (1 || !FFlag::DebugLuauDeferredConstraintResolution)
+    if (1 || !FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -865,7 +865,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_ok")
 TEST_CASE_FIXTURE(BuiltinsFixture, "loop_iter_metamethod_ok_with_inference")
 {
     // CLI-116500
-    if (1 || !FFlag::DebugLuauDeferredConstraintResolution)
+    if (1 || !FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -916,7 +916,7 @@ TEST_CASE_FIXTURE(Fixture, "for_loop_lower_bound_is_string_3")
 TEST_CASE_FIXTURE(BuiltinsFixture, "cli_68448_iterators_need_not_accept_nil")
 {
     // CLI-116500
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1051,7 +1051,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_iteration_fragmented_keys")
 TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_xpath_candidates")
 {
     // CLI-116500
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1071,7 +1071,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_xpath_candidates")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_iteration_on_never_gives_never")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1084,7 +1084,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_iteration_on_never_gives_never")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("never?" == toString(requireType("ans"))); // CLI-114134 egraph simplification.  Should just be nil.
     else
         CHECK(toString(requireType("ans")) == "never");
@@ -1093,7 +1093,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dcr_iteration_on_never_gives_never")
 TEST_CASE_FIXTURE(BuiltinsFixture, "iterate_over_properties")
 {
     // CLI-116498 - Sometimes you can iterate over tables with no indexer.
-    ScopedFastFlag sff0{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff0{FFlag::LuauSolverV2, false};
 
     ScopedFastFlag sff{FFlag::LuauOkWithIteratingOverTableProperties, true};
 
@@ -1151,7 +1151,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "pairs_should_not_retroactively_add_an_indexe
         print(prices.wwwww)
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // We regress a little here: The old solver would typecheck the first
         // access to prices.wwwww on a table that had no indexer, and the second
@@ -1186,7 +1186,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "iterate_array_of_singletons")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_ERRORS(result);
@@ -1210,7 +1210,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "iter_mm_results_are_lvalue")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "forin_metatable_no_iter_mm")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local t = setmetatable({1, 2, 3}, {})
@@ -1228,7 +1228,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "forin_metatable_no_iter_mm")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "forin_metatable_iter_mm")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type Iterable<T...> = typeof(setmetatable({}, {} :: {

tests/TypeInfer.modules.test.cpp

@@ -11,7 +11,7 @@
 #include "doctest.h"
 
 LUAU_FASTFLAG(LuauInstantiateInSubtyping)
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 using namespace Luau;
 
@@ -56,7 +56,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "require")
         return {hooty=hooty}
     )";
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         fileResolver.source["game/B"] = R"(
             local Hooty = require(game.A)
@@ -237,7 +237,7 @@ local tbl: string = require(game.A)
 
     CheckResult result = frontend.check("game/B");
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("Type '{ def: number }' could not be converted into 'string'", toString(result.errors[0]));
     else
         CHECK_EQ("Type '{| def: number |}' could not be converted into 'string'", toString(result.errors[0]));
@@ -424,7 +424,7 @@ local b: B.T = a
     CheckResult result = frontend.check("game/C");
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == "Type 'T' could not be converted into 'T'; at [read \"x\"], number is not exactly string");
     else
     {
@@ -465,7 +465,7 @@ local b: B.T = a
     CheckResult result = frontend.check("game/D");
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == "Type 'T' could not be converted into 'T'; at [read \"x\"], number is not exactly string");
     else
     {

tests/TypeInfer.negations.test.cpp

@@ -51,7 +51,7 @@ TEST_CASE_FIXTURE(NegationFixture, "string_is_not_a_subtype_of_negated_string")
 TEST_CASE_FIXTURE(Fixture, "cofinite_strings_can_be_compared_for_equality")
 {
     // CLI-117082 Cofinite strings cannot be compared for equality because normalization produces a large type with cycles
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         function f(e)

tests/TypeInfer.oop.test.cpp

@@ -12,14 +12,14 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("TypeInferOOP");
 
 TEST_CASE_FIXTURE(Fixture, "dont_suggest_using_colon_rather_than_dot_if_not_defined_with_colon")
 {
     // CLI-116571 method calls are missing arity checking?
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local someTable = {}
@@ -37,7 +37,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_suggest_using_colon_rather_than_dot_if_not_defi
 TEST_CASE_FIXTURE(Fixture, "dont_suggest_using_colon_rather_than_dot_if_it_wont_help_2")
 {
     // CLI-116571 method calls are missing arity checking?
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local someTable = {}
@@ -144,7 +144,7 @@ TEST_CASE_FIXTURE(Fixture, "inferring_hundreds_of_self_calls_should_not_suffocat
     )");
 
     ModulePtr module = getMainModule();
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_GE(80, module->internalTypes.types.size());
     else
         CHECK_GE(50, module->internalTypes.types.size());
@@ -346,7 +346,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "augmenting_an_unsealed_table_with_a_metatabl
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("{ @metatable { number: number }, { method: (unknown) -> string } }" == toString(requireType("B"), {true}));
     else
         CHECK("{ @metatable { number: number }, { method: <a>(a) -> string } }" == toString(requireType("B"), {true}));
@@ -505,7 +505,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "promise_type_error_too_complex" * doctest::t
 
 TEST_CASE_FIXTURE(Fixture, "method_should_not_create_cyclic_type")
 {
-    ScopedFastFlag sff(FFlag::DebugLuauDeferredConstraintResolution, true);
+    ScopedFastFlag sff(FFlag::LuauSolverV2, true);
 
     CheckResult result = check(R"(
         local Component = {}

tests/TypeInfer.operators.test.cpp

@@ -16,7 +16,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauRemoveBadRelationalOperatorWarning)
 
 TEST_SUITE_BEGIN("TypeInferOperators");
@@ -194,7 +194,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_overloaded_multiply_that_is_an_int
     CHECK("Vec3" == toString(requireType("c")));
     CHECK("Vec3" == toString(requireType("d")));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("mul<Vec3, string>" == toString(requireType("e")));
     else
         CHECK_EQ("Vec3", toString(requireType("e")));
@@ -232,7 +232,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_overloaded_multiply_that_is_an_int
     CHECK("Vec3" == toString(requireType("c")));
     CHECK("Vec3" == toString(requireType("d")));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("mul<string, Vec3>" == toString(requireType("e")));
     else
         CHECK_EQ("Vec3", toString(requireType("e")));
@@ -270,7 +270,7 @@ TEST_CASE_FIXTURE(Fixture, "cannot_indirectly_compare_types_that_do_not_have_a_m
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
@@ -300,7 +300,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "cannot_indirectly_compare_types_that_do_not_
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
@@ -404,7 +404,7 @@ TEST_CASE_FIXTURE(Fixture, "compound_assign_mismatch_result")
         s += 10
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK_EQ(result.errors[0], (TypeError{Location{{2, 8}, {2, 9}}, TypeMismatch{builtinTypes->numberType, builtinTypes->stringType}}));
@@ -441,7 +441,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "compound_assign_metatable")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "compound_assign_metatable_with_changing_return_type")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         --!strict
@@ -567,7 +567,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_unary_minus")
     CHECK_EQ("string", toString(requireType("a")));
     CHECK_EQ("number", toString(requireType("b")));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
 
@@ -607,7 +607,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_unary_minus_error")
         local a = -foo
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
 
@@ -631,7 +631,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_unary_minus_error")
 TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_unary_len_error")
 {
     // CLI-116463
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -702,7 +702,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "disallow_string_and_types_without_metatables
 
     LUAU_REQUIRE_ERROR_COUNT(3, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(get<UninhabitedTypeFunction>(result.errors[0]));
         CHECK(Location{{2, 18}, {2, 30}} == result.errors[0].location);
@@ -720,7 +720,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "disallow_string_and_types_without_metatables
 
         GenericError* gen1 = get<GenericError>(result.errors[1]);
         REQUIRE(gen1);
-        if (FFlag::DebugLuauDeferredConstraintResolution)
+        if (FFlag::LuauSolverV2)
             CHECK_EQ(gen1->message, "Operator + is not applicable for '{ value: number }' and 'number' because neither type has a metatable");
         else
             CHECK_EQ(gen1->message, "Binary operator '+' not supported by types 'foo' and 'number'");
@@ -753,7 +753,7 @@ TEST_CASE_FIXTURE(Fixture, "concat_op_on_free_lhs_and_string_rhs")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK("<a>(a) -> concat<a, string>" == toString(requireType("f")));
@@ -775,7 +775,7 @@ TEST_CASE_FIXTURE(Fixture, "concat_op_on_string_lhs_and_free_rhs")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("<a>(a) -> concat<string, a>" == toString(requireType("f")));
     else
         CHECK_EQ("(string) -> string", toString(requireType("f")));
@@ -794,7 +794,7 @@ TEST_CASE_FIXTURE(Fixture, "strict_binary_op_where_lhs_unknown")
 
     CheckResult result = check(src);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(ops.size(), result);
         CHECK_EQ(
@@ -821,7 +821,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "and_binexps_dont_unify")
     )");
 
     // This infers a type for `t` of `{unknown}`, and so it makes sense that `t[1].test` would error.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_ERROR_COUNT(1, result);
     else
         LUAU_REQUIRE_NO_ERRORS(result);
@@ -837,7 +837,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
@@ -860,7 +860,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
     )");
 
     // If DCR is off and the flag to remove this check in the old solver is on, the expected behavior is no errors.
-    if (!FFlag::DebugLuauDeferredConstraintResolution && FFlag::LuauRemoveBadRelationalOperatorWarning)
+    if (!FFlag::LuauSolverV2 && FFlag::LuauRemoveBadRelationalOperatorWarning)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         return;
@@ -868,7 +868,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
@@ -885,7 +885,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
 TEST_CASE_FIXTURE(Fixture, "cli_38355_recursive_union")
 {
     // There's an extra spurious warning here when the new solver is enabled.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -901,7 +901,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "UnknownGlobalCompoundAssign")
 {
     // In non-strict mode, global definition is still allowed
     {
-        if (!FFlag::DebugLuauDeferredConstraintResolution)
+        if (!FFlag::LuauSolverV2)
         {
             CheckResult result = check(R"(
                 --!nonstrict
@@ -928,7 +928,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "UnknownGlobalCompoundAssign")
 
     // In non-strict mode, compound assignment is not a definition, it's a modification
     {
-        if (!FFlag::DebugLuauDeferredConstraintResolution)
+        if (!FFlag::LuauSolverV2)
         {
             CheckResult result = check(R"(
                 --!nonstrict
@@ -1047,7 +1047,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_any_in_all_modes_when_lhs_is_unknown")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> add<a, b>");
@@ -1079,7 +1079,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_subtraction")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> sub<a, b>");
@@ -1099,7 +1099,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_multiplication")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> mul<a, b>");
@@ -1119,7 +1119,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_division")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> div<a, b>");
@@ -1139,7 +1139,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_floor_division")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> idiv<a, b>");
@@ -1159,7 +1159,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_exponentiation")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> pow<a, b>");
@@ -1179,7 +1179,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_modulo")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> mod<a, b>");
@@ -1199,7 +1199,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_type_for_generic_concat")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK(toString(requireType("f")) == "<a, b>(a, b) -> concat<a, b>");
@@ -1294,7 +1294,7 @@ TEST_CASE_FIXTURE(Fixture, "unrelated_primitives_cannot_be_compared")
 TEST_CASE_FIXTURE(BuiltinsFixture, "mm_comparisons_must_return_a_boolean")
 {
     // CLI-115687
-    if (1 || !FFlag::DebugLuauDeferredConstraintResolution)
+    if (1 || !FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1341,12 +1341,12 @@ local w = c and 1
 
     CHECK("number?" == toString(requireType("x")));
     CHECK("number" == toString(requireType("y")));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("false | number" == toString(requireType("z")));
     else
         CHECK("boolean | number" == toString(requireType("z"))); // 'false' widened to boolean
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("number?" == toString(requireType("w")));
     else
         CHECK("(boolean | number)?" == toString(requireType("w")));
@@ -1372,7 +1372,7 @@ local f1 = f or 'f'
 
     CHECK("number | string" == toString(requireType("a1")));
     CHECK("number" == toString(requireType("b1")));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("string | true" == toString(requireType("c1")));
         CHECK("string | true" == toString(requireType("d1")));
@@ -1426,7 +1426,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "luau_polyfill_is_array_simplified")
 TEST_CASE_FIXTURE(BuiltinsFixture, "luau_polyfill_is_array")
 {
     // CLI-116480 Subtyping bug: table should probably be a subtype of {[unknown]: unknown}
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -1524,7 +1524,7 @@ return startsWith
 
 TEST_CASE_FIXTURE(Fixture, "add_type_function_works")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1584,7 +1584,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "compare_singleton_string_to_string")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "no_infinite_expansion_of_free_type" * doctest::timeout(1.0))
 {
-    ScopedFastFlag sff(FFlag::DebugLuauDeferredConstraintResolution, true);
+    ScopedFastFlag sff(FFlag::LuauSolverV2, true);
     check(R"(
         local tooltip = {}
 

tests/TypeInfer.primitives.test.cpp

@@ -84,7 +84,7 @@ TEST_CASE_FIXTURE(Fixture, "check_methods_of_number")
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("Expected type table, got 'number' instead" == toString(result.errors[0]));
         CHECK("Type 'number' could not be converted into 'string'" == toString(result.errors[1]));

tests/TypeInfer.provisional.test.cpp

@@ -10,7 +10,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTINT(LuauNormalizeCacheLimit);
 LUAU_FASTINT(LuauTarjanChildLimit);
 LUAU_FASTINT(LuauTypeInferIterationLimit);
@@ -65,7 +65,7 @@ TEST_CASE_FIXTURE(Fixture, "typeguard_inference_incomplete")
         end
     )";
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(expectedWithNewSolver, decorateWithTypes(code));
     else
         CHECK_EQ(expected, decorateWithTypes(code));
@@ -73,7 +73,7 @@ TEST_CASE_FIXTURE(Fixture, "typeguard_inference_incomplete")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "luau-polyfill.Array.filter")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     // This test exercises the fact that we should reduce sealed/unsealed/free tables
     // res is a unsealed table with type {((T & ~nil)?) & any}
@@ -172,7 +172,7 @@ TEST_CASE_FIXTURE(Fixture, "it_should_be_agnostic_of_actual_size")
 // For now, infer it as just a free table.
 TEST_CASE_FIXTURE(BuiltinsFixture, "setmetatable_constrains_free_type_into_free_table")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a = {}
@@ -192,7 +192,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "setmetatable_constrains_free_type_into_free_
 // Luau currently doesn't yet know how to allow assignments when the binding was refined.
 TEST_CASE_FIXTURE(Fixture, "while_body_are_also_refined")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Node<T> = { value: T, child: Node<T>? }
@@ -217,7 +217,7 @@ TEST_CASE_FIXTURE(Fixture, "while_body_are_also_refined")
 // We should be type checking the metamethod at the call site of setmetatable.
 TEST_CASE_FIXTURE(BuiltinsFixture, "error_on_eq_metamethod_returning_a_type_other_than_boolean")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local tab = {a = 1}
@@ -277,7 +277,7 @@ TEST_CASE_FIXTURE(Fixture, "discriminate_from_x_not_equal_to_nil")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("{ x: string, y: number }", toString(requireTypeAtPosition({5, 28})));
         CHECK_EQ("{ x: nil, y: nil }", toString(requireTypeAtPosition({7, 28})));
@@ -359,7 +359,7 @@ TEST_CASE_FIXTURE(Fixture, "do_not_ice_when_trying_to_pick_first_of_generic_type
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("() -> ()" == toString(requireType("f")));
         CHECK("() -> ()" == toString(requireType("g")));
@@ -382,7 +382,7 @@ TEST_CASE_FIXTURE(Fixture, "specialization_binds_with_prototypes_too_early")
         local s2s: (string) -> string = id
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_ERRORS(result); // Should not have any errors.
@@ -393,7 +393,7 @@ TEST_CASE_FIXTURE(Fixture, "weird_fail_to_unify_type_pack")
     ScopedFastFlag sff[] = {
         // I'm not sure why this is broken without DCR, but it seems to be fixed
         // when DCR is enabled.
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     CheckResult result = check(R"(
@@ -477,7 +477,7 @@ TEST_CASE_FIXTURE(Fixture, "free_is_not_bound_to_any")
 TEST_CASE_FIXTURE(Fixture, "dcr_can_partially_dispatch_a_constraint")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     CheckResult result = check(R"(
@@ -509,7 +509,7 @@ TEST_CASE_FIXTURE(Fixture, "dcr_can_partially_dispatch_a_constraint")
     // to be solved later.  This should be faster and theoretically less prone
     // to cyclic constraint dependencies.
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(unknown, number) -> ()" == toString(requireType("prime_iter")));
     else
         CHECK("<a>(a, number) -> ()" == toString(requireType("prime_iter")));
@@ -517,7 +517,7 @@ TEST_CASE_FIXTURE(Fixture, "dcr_can_partially_dispatch_a_constraint")
 
 TEST_CASE_FIXTURE(Fixture, "free_options_cannot_be_unified_together")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     TypeArena arena;
     TypeId nilType = builtinTypes->nilType;
@@ -535,7 +535,7 @@ TEST_CASE_FIXTURE(Fixture, "free_options_cannot_be_unified_together")
     Normalizer normalizer{&arena, builtinTypes, NotNull{&sharedState}};
     Unifier u{NotNull{&normalizer}, NotNull{scope.get()}, Location{}, Variance::Covariant};
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         u.enableNewSolver();
 
     u.tryUnify(option1, option2);
@@ -553,7 +553,7 @@ TEST_CASE_FIXTURE(Fixture, "free_options_cannot_be_unified_together")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "for_in_loop_with_zero_iterators")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function no_iter() end
@@ -600,7 +600,7 @@ return wrapStrictTable(Constants, "Constants")
 
     std::optional<TypeId> result = first(m->returnType);
     REQUIRE(result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("unknown", toString(*result));
     else
         CHECK_MESSAGE(get<AnyType>(*result), *result);
@@ -643,7 +643,7 @@ return wrapStrictTable(Constants, "Constants")
     std::optional<TypeId> result = first(m->returnType);
     REQUIRE(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("unknown" == toString(*result));
     else
         CHECK("any" == toString(*result));
@@ -829,7 +829,7 @@ TEST_CASE_FIXTURE(Fixture, "assign_table_with_refined_property_with_a_similar_ty
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result); // This is wrong.  We should be rejecting this assignment.
     else
     {
@@ -847,7 +847,7 @@ Type 'number?' could not be converted into 'number' in an invariant context)";
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "table_insert_with_a_singleton_argument")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function foo(t, x)
@@ -864,7 +864,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_insert_with_a_singleton_argument")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{string}", toString(requireType("t")));
     else
     {
@@ -904,7 +904,7 @@ TEST_CASE_FIXTURE(Fixture, "expected_type_should_be_a_helpful_deduction_guide_fo
         local x: Ref<number?> = useRef(nil)
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // This bug is fixed in the new solver.
         LUAU_REQUIRE_ERROR_COUNT(1, result);
@@ -921,7 +921,7 @@ TEST_CASE_FIXTURE(Fixture, "expected_type_should_be_a_helpful_deduction_guide_fo
 
 TEST_CASE_FIXTURE(Fixture, "floating_generics_should_not_be_allowed")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local assign : <T, U, V, W>(target: T, source0: U?, source1: V?, source2: W?, ...any) -> T & U & V & W = (nil :: any)
@@ -945,7 +945,7 @@ TEST_CASE_FIXTURE(Fixture, "floating_generics_should_not_be_allowed")
 
 TEST_CASE_FIXTURE(Fixture, "free_options_can_be_unified_together")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     TypeArena arena;
     TypeId nilType = builtinTypes->nilType;
@@ -963,7 +963,7 @@ TEST_CASE_FIXTURE(Fixture, "free_options_can_be_unified_together")
     Normalizer normalizer{&arena, builtinTypes, NotNull{&sharedState}};
     Unifier u{NotNull{&normalizer}, NotNull{scope.get()}, Location{}, Variance::Covariant};
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         u.enableNewSolver();
 
     u.tryUnify(option1, option2);
@@ -992,7 +992,7 @@ TEST_CASE_FIXTURE(Fixture, "unify_more_complex_unions_that_include_nil")
 
 TEST_CASE_FIXTURE(Fixture, "optional_class_instances_are_invariant_old_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     createSomeClasses(&frontend);
 
@@ -1010,7 +1010,7 @@ TEST_CASE_FIXTURE(Fixture, "optional_class_instances_are_invariant_old_solver")
 
 TEST_CASE_FIXTURE(Fixture, "optional_class_instances_are_invariant_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     createSomeClasses(&frontend);
 
@@ -1076,7 +1076,7 @@ end
 TEST_CASE_FIXTURE(BuiltinsFixture, "table_unification_infinite_recursion")
 {
     // The new solver doesn't recurse as heavily in this situation.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
 #if defined(_NOOPT) || defined(_DEBUG)
     ScopedFastInt LuauTypeInferRecursionLimit{FInt::LuauTypeInferRecursionLimit, 100};
@@ -1113,7 +1113,7 @@ tbl:f3()
 TEST_CASE_FIXTURE(BuiltinsFixture, "normalization_limit_in_unify_with_any")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     // With default limit, this test will take 10 seconds in NoOpt
@@ -1148,7 +1148,7 @@ foo(1 :: any)
 
 TEST_CASE_FIXTURE(Fixture, "luau_roact_useState_nilable_state_1")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type Dispatch<A> = (A) -> ()
@@ -1173,7 +1173,7 @@ TEST_CASE_FIXTURE(Fixture, "luau_roact_useState_nilable_state_1")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
     {
@@ -1189,7 +1189,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "luau_roact_useState_minimization")
 {
     // We don't expect this test to work on the old solver, but it also does not yet work on the new solver.
     // So, we can't just put a scoped fast flag here, or it would block CI.
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -1307,7 +1307,7 @@ TEST_CASE_FIXTURE(Fixture, "we_cannot_infer_functions_that_return_inconsistently
 #else
     // This is what actually happens right now.
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_CHECK_ERROR_COUNT(2, result);
 

tests/TypeInfer.refinements.test.cpp

@@ -7,7 +7,7 @@
 
 #include "doctest.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 using namespace Luau;
 
@@ -255,7 +255,7 @@ TEST_CASE_FIXTURE(Fixture, "a_and_b_or_a_and_c")
 
     CHECK_EQ("string", toString(requireTypeAtPosition({3, 28})));
     CHECK_EQ("number?", toString(requireTypeAtPosition({4, 28})));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("boolean", toString(requireTypeAtPosition({5, 28})));
     else
         CHECK_EQ("true", toString(requireTypeAtPosition({5, 28}))); // oh no! :(
@@ -278,7 +278,7 @@ TEST_CASE_FIXTURE(Fixture, "type_assertion_expr_carry_its_constraints")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("number?", toString(requireTypeAtPosition({3, 26})));
         CHECK_EQ("string?", toString(requireTypeAtPosition({4, 26})));
@@ -307,7 +307,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typeguard_in_if_condition_position")
     LUAU_REQUIRE_NO_ERRORS(result);
 
     // DCR changes refinements to preserve error suppression.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("*error-type* | number", toString(requireTypeAtPosition({3, 26})));
     else
         CHECK_EQ("number", toString(requireTypeAtPosition({3, 26})));
@@ -326,7 +326,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typeguard_in_assert_position")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("<a>(a) -> a & number" == toString(requireType("f")));
     else
         CHECK("<a>(a) -> number" == toString(requireType("f")));
@@ -346,7 +346,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_test_a_prop")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
     {
@@ -376,7 +376,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_test_a_nested_p
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         const UnknownProperty* up = get<UnknownProperty>(result.errors[0]);
@@ -410,7 +410,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_test_a_tested_n
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
     {
@@ -486,7 +486,7 @@ TEST_CASE_FIXTURE(Fixture, "truthy_constraint_on_properties")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 - Types produced by refinements don't always get simplified
         CHECK("{ x: number? } & { x: ~(false?) }" == toString(requireTypeAtPosition({4, 23})));
@@ -573,7 +573,7 @@ TEST_CASE_FIXTURE(Fixture, "term_is_equal_to_an_lvalue")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(toString(requireTypeAtPosition({3, 28})), R"("hello")");                         // a == "hello"
         CHECK_EQ(toString(requireTypeAtPosition({5, 28})), R"(((string & ~"hello") | number)?)"); // a ~= "hello"
@@ -600,7 +600,7 @@ TEST_CASE_FIXTURE(Fixture, "lvalue_is_not_nil")
     LUAU_REQUIRE_NO_ERRORS(result);
 
     CHECK_EQ(toString(requireTypeAtPosition({3, 28})), "number | string"); // a ~= nil
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireTypeAtPosition({5, 28})), "nil"); // a == nil :)
     else
         CHECK_EQ(toString(requireTypeAtPosition({5, 28})), "(number | string)?"); // a == nil
@@ -618,7 +618,7 @@ TEST_CASE_FIXTURE(Fixture, "free_type_is_equal_to_an_lvalue")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireTypeAtPosition({3, 33})), "unknown"); // a == b
     else
         CHECK_EQ(toString(requireTypeAtPosition({3, 33})), "a"); // a == b
@@ -639,7 +639,7 @@ TEST_CASE_FIXTURE(Fixture, "unknown_lvalue_is_not_synonymous_with_other_on_not_e
     LUAU_REQUIRE_NO_ERRORS(result);
 
     CHECK_EQ(toString(requireTypeAtPosition({3, 33})), "any"); // a ~= b
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireTypeAtPosition({3, 36})), "{ x: number }?"); // a ~= b
     else
         CHECK_EQ(toString(requireTypeAtPosition({3, 36})), "{| x: number |}?"); // a ~= b
@@ -664,7 +664,7 @@ TEST_CASE_FIXTURE(Fixture, "string_not_equal_to_string_or_nil")
     CHECK_EQ(toString(requireTypeAtPosition({6, 29})), "string");  // a ~= b
     CHECK_EQ(toString(requireTypeAtPosition({6, 32})), "string?"); // a ~= b
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(toString(requireTypeAtPosition({8, 29})), "string?"); // a == b
         CHECK_EQ(toString(requireTypeAtPosition({8, 32})), "string?"); // a == b
@@ -703,7 +703,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_narrow_to_vector")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("never", toString(requireTypeAtPosition({3, 28})));
     else
         CHECK_EQ("*error-type*", toString(requireTypeAtPosition({3, 28})));
@@ -729,7 +729,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "nonoptional_type_can_narrow_to_nil_if_sense_
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 Types produced by refinements do not consistently get simplified
         CHECK_EQ("(nil & string)?", toString(requireTypeAtPosition({4, 24})));    // type(v) == "nil"
@@ -780,7 +780,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typeguard_narrows_for_table")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ x: number } | { y: boolean }", toString(requireTypeAtPosition({3, 28}))); // type(x) == "table"
     else
         CHECK_EQ("{| x: number |} | {| y: boolean |}", toString(requireTypeAtPosition({3, 28}))); // type(x) == "table"
@@ -822,7 +822,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_guard_can_filter_for_intersection_of_ta
 
     ToStringOptions opts;
     opts.exhaustive = true;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ x: number } & { y: number }", toString(requireTypeAtPosition({4, 28}), opts));
     else
         CHECK_EQ("{| x: number |} & {| y: number |}", toString(requireTypeAtPosition({4, 28}), opts));
@@ -863,7 +863,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_guard_narrowed_into_nothingness")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 Types produced by refinements do not consistently get simplified
         CHECK_EQ("{ x: number } & ~table", toString(requireTypeAtPosition({3, 28})));
@@ -955,7 +955,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "either_number_or_string")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("*error-type* | number | string", toString(requireTypeAtPosition({3, 28})));
     else
         CHECK_EQ("number | string", toString(requireTypeAtPosition({3, 28})));
@@ -974,7 +974,7 @@ TEST_CASE_FIXTURE(Fixture, "not_t_or_some_prop_of_t")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 Types produced by refinements do not consistently get simplified
         CHECK_EQ("({ x: boolean } & { x: ~(false?) })?", toString(requireTypeAtPosition({3, 28})));
@@ -1082,7 +1082,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_comparison_ifelse_expression")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("*error-type* | number", toString(requireTypeAtPosition({6, 49})));
         CHECK_EQ("*error-type* | ~number", toString(requireTypeAtPosition({6, 66})));
@@ -1094,7 +1094,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_comparison_ifelse_expression")
     }
 
     CHECK_EQ("number", toString(requireTypeAtPosition({10, 49})));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("~number", toString(requireTypeAtPosition({10, 66})));
     else
         CHECK_EQ("unknown", toString(requireTypeAtPosition({10, 66})));
@@ -1224,7 +1224,7 @@ TEST_CASE_FIXTURE(Fixture, "discriminate_from_truthiness_of_x")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 Types produced by refinements do not consistently get simplified
         CHECK("{ tag: \"exists\", x: string } & { x: ~(false?) }" == toString(requireTypeAtPosition({5, 28})));
@@ -1360,7 +1360,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "discriminate_from_isa_of_x")
     LUAU_REQUIRE_NO_ERRORS(result);
 
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(R"({ tag: "Part", x: Part })" == toString(requireTypeAtPosition({5, 28})));
         CHECK(R"({ tag: "Folder", x: Folder })" == toString(requireTypeAtPosition({7, 28})));
@@ -1375,7 +1375,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "discriminate_from_isa_of_x")
 TEST_CASE_FIXTURE(RefinementClassFixture, "typeguard_cast_free_table_to_vector")
 {
     // CLI-115286 - Refining via type(x) == 'vector' does not work in the new solver
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f(vec)
@@ -1450,7 +1450,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "type_narrow_but_the_discriminant_type
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("never", toString(requireTypeAtPosition({3, 28})));
         CHECK_EQ("Instance | Vector3 | number | string", toString(requireTypeAtPosition({5, 28})));
@@ -1501,7 +1501,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "narrow_from_subclasses_of_instance_or
 TEST_CASE_FIXTURE(RefinementClassFixture, "x_as_any_if_x_is_instance_elseif_x_is_table")
 {
     // CLI-117136 - this code doesn't finish constraint solving and has blocked types in the output
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         --!nonstrict
@@ -1517,7 +1517,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "x_as_any_if_x_is_instance_elseif_x_is
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("Folder & Instance & {-  -}", toString(requireTypeAtPosition({5, 28})));
         CHECK_EQ("(~Folder | ~Instance) & {-  -} & never", toString(requireTypeAtPosition({7, 28})));
@@ -1569,7 +1569,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "isa_type_refinement_must_be_known_ahe
 {
     // CLI-115087 - The new solver does not consistently combine tables with
     // class types when they appear in the upper bounds of a free type.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f(x): Instance
@@ -1592,7 +1592,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "isa_type_refinement_must_be_known_ahe
 TEST_CASE_FIXTURE(RefinementClassFixture, "x_is_not_instance_or_else_not_part")
 {
     // CLI-117135 - RefinementTests.x_is_not_instance_or_else_not_part not correctly applying refinements to a function parameter
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         local function f(x: Part | Folder | string)
@@ -1641,7 +1641,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknowns")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("string", toString(requireTypeAtPosition({3, 28})));
         CHECK_EQ("~string", toString(requireTypeAtPosition({5, 28})));
@@ -1779,7 +1779,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_take_the_length
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK_EQ("table", toString(requireTypeAtPosition({3, 29})));
@@ -1801,7 +1801,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_clone_it")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
     }
@@ -1814,7 +1814,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table_then_clone_it")
 TEST_CASE_FIXTURE(RefinementClassFixture, "refine_a_param_that_got_resolved_during_constraint_solving_stage")
 {
     // CLI-117134 - Applying a refinement causes an optional value access error.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         type Id<T> = T
@@ -1849,7 +1849,7 @@ TEST_CASE_FIXTURE(RefinementClassFixture, "refine_a_param_that_got_resolved_duri
 
     LUAU_REQUIRE_NO_ERRORS(result);
     CHECK_EQ("Part", toString(requireTypeAtPosition({5, 28})));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("Instance & ~Part", toString(requireTypeAtPosition({7, 28})));
     else
         CHECK_EQ("Instance", toString(requireTypeAtPosition({7, 28})));
@@ -1865,7 +1865,7 @@ TEST_CASE_FIXTURE(Fixture, "refine_a_property_of_some_global")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(3, result);
 
@@ -1908,7 +1908,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dataflow_analysis_can_tell_refinements_when_
     CHECK_EQ("nil", toString(requireTypeAtPosition({12, 28})));
     CHECK_EQ("string", toString(requireTypeAtPosition({14, 28})));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115281 - Types produced by refinements don't always get simplified
         CHECK_EQ("nil & string", toString(requireTypeAtPosition({18, 28})));
@@ -1998,7 +1998,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_annotations_arent_relevant_when_doing_d
     LUAU_REQUIRE_NO_ERRORS(result);
 
     CHECK_EQ("nil", toString(requireTypeAtPosition({8, 28})));
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115478 - This should be never
         CHECK_EQ("nil", toString(requireTypeAtPosition({9, 28})));
@@ -2009,7 +2009,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_annotations_arent_relevant_when_doing_d
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "function_call_with_colon_after_refining_not_to_be_nil")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         --!strict
@@ -2049,7 +2049,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refinements_should_preserve_error_suppressio
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_NO_ERRORS(result);
@@ -2075,7 +2075,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "many_refinements_on_val")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
     // this test is DCR-only as an instance of DCR fixing a bug in the old solver
 
     CheckResult result = check(R"(
@@ -2097,7 +2097,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "conditional_refinement_should_stay_error_suppressing")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function test(element: any?)
@@ -2118,7 +2118,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "globals_can_be_narrowed_too")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114134
         CHECK("string & typeof(string)" == toString(requireTypeAtPosition(Position{2, 24})));

tests/TypeInfer.singletons.test.cpp

@@ -6,7 +6,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("TypeSingletons");
 
@@ -46,7 +46,7 @@ TEST_CASE_FIXTURE(Fixture, "string_singletons")
 
 TEST_CASE_FIXTURE(Fixture, "string_singleton_function_call")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -153,7 +153,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_function_call_with_singletons")
 
 TEST_CASE_FIXTURE(Fixture, "overloaded_function_call_with_singletons_mismatch")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(g: ((true, string) -> ()) & ((false, number) -> ()))
@@ -162,7 +162,7 @@ TEST_CASE_FIXTURE(Fixture, "overloaded_function_call_with_singletons_mismatch")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("None of the overloads for function that accept 2 arguments are compatible.", toString(result.errors[0]));
         CHECK_EQ("Available overloads: (true, string) -> (); and (false, number) -> ()", toString(result.errors[1]));
@@ -195,7 +195,7 @@ TEST_CASE_FIXTURE(Fixture, "enums_using_singletons_mismatch")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Type '\"bang\"' could not be converted into '\"bar\" | \"baz\" | \"foo\"'" == toString(result.errors[0]));
     else
         CHECK_EQ(
@@ -256,7 +256,7 @@ TEST_CASE_FIXTURE(Fixture, "tagged_unions_immutable_tag")
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CannotAssignToNever* tm = get<CannotAssignToNever>(result.errors[0]);
         REQUIRE(tm);
@@ -343,7 +343,7 @@ TEST_CASE_FIXTURE(Fixture, "table_properties_type_error_escapes")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(
             "Type\n"
             "    '{ [\"\\n\"]: number }'\n"
@@ -368,7 +368,7 @@ local a: Animal = { tag = 'cat', cafood = 'something' }
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Type '{ cafood: string, tag: \"cat\" }' could not be converted into 'Cat | Dog'" == toString(result.errors[0]));
     else
     {
@@ -391,7 +391,7 @@ local a: Result = { success = false, result = 'something' }
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Type '{ result: string, success: boolean }' could not be converted into 'Bad | Good'" == toString(result.errors[0]));
     else
     {
@@ -406,7 +406,7 @@ Table type 'a' not compatible with type 'Bad' because the former is missing fiel
 TEST_CASE_FIXTURE(Fixture, "parametric_tagged_union_alias")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
     CheckResult result = check(R"(
         type Ok<T> = {success: true, result: T}
@@ -442,7 +442,7 @@ local a: Animal = if true then { tag = 'cat', catfood = 'something' } else { tag
 
 TEST_CASE_FIXTURE(Fixture, "widen_the_supertype_if_it_is_free_and_subtype_has_singleton")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function foo(f, x)
@@ -462,7 +462,7 @@ TEST_CASE_FIXTURE(Fixture, "widen_the_supertype_if_it_is_free_and_subtype_has_si
 
 TEST_CASE_FIXTURE(Fixture, "return_type_of_f_is_not_widened")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function foo(f, x): "hello"? -- anyone there?
@@ -488,7 +488,7 @@ TEST_CASE_FIXTURE(Fixture, "widening_happens_almost_everywhere")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(R"("foo")", toString(requireType("copy")));
     else
         CHECK_EQ("string", toString(requireType("copy")));
@@ -613,7 +613,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "singletons_stick_around_under_assignment")
         print(kind == "Bar") -- type of equality refines to `false`
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_ERROR_COUNT(1, result);

tests/TypeInfer.tables.test.cpp

@@ -15,7 +15,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauInstantiateInSubtyping)
 LUAU_FASTFLAG(LuauFixIndexerSubtypingOrdering)
 LUAU_FASTFLAG(LuauAcceptIndexingTableUnionsIntersections)
@@ -26,7 +26,7 @@ TEST_SUITE_BEGIN("TableTests");
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "generalization_shouldnt_seal_table_in_len_function_fn")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
 local t = {}
@@ -136,7 +136,7 @@ TEST_CASE_FIXTURE(Fixture, "index_expression_is_checked_against_the_indexer_type
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_MESSAGE(get<CannotExtendTable>(result.errors[0]), "Expected CannotExtendTable but got " << toString(result.errors[0]));
     else
         CHECK(get<TypeMismatch>(result.errors[0]));
@@ -163,7 +163,7 @@ TEST_CASE_FIXTURE(Fixture, "cannot_augment_sealed_table")
 
     // TODO: better, more robust comparison of type vars
     auto s = toString(error->tableType, ToStringOptions{/*exhaustive*/ true});
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(s, "{ prop: number }");
     else
         CHECK_EQ(s, "{| prop: number |}");
@@ -318,7 +318,7 @@ TEST_CASE_FIXTURE(Fixture, "call_method_with_explicit_self_argument")
 TEST_CASE_FIXTURE(Fixture, "used_dot_instead_of_colon")
 {
     // CLI-114792 Dot vs colon warnings aren't in the new solver yet.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local T = {}
@@ -371,7 +371,7 @@ TEST_CASE_FIXTURE(Fixture, "used_dot_instead_of_colon_but_correctly")
 TEST_CASE_FIXTURE(Fixture, "used_colon_instead_of_dot")
 {
     // CLI-114792 Dot vs colon warnings aren't in the new solver yet.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local T = {}
@@ -396,7 +396,7 @@ TEST_CASE_FIXTURE(Fixture, "used_colon_instead_of_dot")
 TEST_CASE_FIXTURE(Fixture, "open_table_unification_2")
 {
     // CLI-114792 We don't report MissingProperties in many places where the old solver does.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a = {}
@@ -480,7 +480,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_param_width_subtyping_2")
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
     // CLI 114792 We don't report MissingProperties in many places where the old solver does
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         TypeMismatch* error = get<TypeMismatch>(result.errors[0]);
         REQUIRE_MESSAGE(error != nullptr, "Expected TypeMismatch but got " << toString(result.errors[0]));
@@ -513,7 +513,7 @@ TEST_CASE_FIXTURE(Fixture, "table_param_width_subtyping_3")
 
     CHECK(result.errors[0].location == Location{Position{6, 8}, Position{6, 9}});
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors[0]) == "Type 'T' could not be converted into '{ read baz: unknown }'");
     else
     {
@@ -536,7 +536,7 @@ TEST_CASE_FIXTURE(Fixture, "table_param_width_subtyping_3")
 TEST_CASE_FIXTURE(Fixture, "table_unification_4")
 {
     // CLI-114134 - Use egraphs to simplify types better.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function foo(o)
@@ -567,7 +567,7 @@ TEST_CASE_FIXTURE(Fixture, "ok_to_add_property_to_free_table")
 TEST_CASE_FIXTURE(Fixture, "okay_to_add_property_to_unsealed_tables_by_assignment")
 {
     // CLI-114872
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -586,7 +586,7 @@ TEST_CASE_FIXTURE(Fixture, "okay_to_add_property_to_unsealed_tables_by_assignmen
 TEST_CASE_FIXTURE(Fixture, "okay_to_add_property_to_unsealed_tables_by_function_call")
 {
     // CLI-114873
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -691,7 +691,7 @@ TEST_CASE_FIXTURE(Fixture, "indexers_get_quantified_too")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("({unknown}) -> ()" == toString(requireType("swap")));
     else
     {
@@ -763,7 +763,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_indexer_from_array_like_table")
 
     CHECK_EQ(*builtinTypes->numberType, *indexer.indexType);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114134 - Use egraphs to simplify types
         CHECK("string | string | string" == toString(indexer.indexResultType));
@@ -802,7 +802,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_indexer_from_value_property_in_literal")
     CHECK(bool(retType->indexer));
 
     const TableIndexer& indexer = *retType->indexer;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ __name: string }", toString(indexer.indexType));
     else
         CHECK_EQ("{| __name: string |}", toString(indexer.indexType));
@@ -811,7 +811,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_indexer_from_value_property_in_literal")
 TEST_CASE_FIXTURE(Fixture, "infer_indexer_from_its_variable_type_and_unifiable")
 {
     // This code is totally different in the new solver.  We instead create a new type state for t2.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t1: { [string]: string } = {}
@@ -851,7 +851,7 @@ TEST_CASE_FIXTURE(Fixture, "indexer_mismatch")
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm != nullptr);
     CHECK(toString(tm->wantedType) == "{number}");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(tm->givenType) == "{ [string]: string }");
     else
         CHECK(toString(tm->givenType) == "{| [string]: string |}");
@@ -893,7 +893,7 @@ TEST_CASE_FIXTURE(Fixture, "sealed_table_value_can_infer_an_indexer")
 
 TEST_CASE_FIXTURE(Fixture, "array_factory_function")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function empty() return {} end
@@ -913,7 +913,7 @@ TEST_CASE_FIXTURE(Fixture, "sealed_table_indexers_must_unify")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114879 - Error path reporting is not great
         CHECK(
@@ -930,7 +930,7 @@ TEST_CASE_FIXTURE(Fixture, "indexer_on_sealed_table_must_unify_with_free_table")
     // CLI-114134 What should be happening here is that the type of `t` should
     // be reduced from `{number} & {string}` to `never`, but that's not
     // happening.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function F(t): {number}
@@ -993,7 +993,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "indexing_from_a_table_should_prefer_properti
 
 TEST_CASE_FIXTURE(Fixture, "any_when_indexing_into_an_unsealed_table_with_no_indexer_in_nonstrict_mode")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -1030,7 +1030,7 @@ TEST_CASE_FIXTURE(Fixture, "disallow_indexing_into_an_unsealed_table_with_no_ind
         local k1 = getConstant("key1")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("unknown" == toString(requireType("k1")));
     else
         CHECK("any" == toString(requireType("k1")));
@@ -1145,7 +1145,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "meta_add_inferred")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "meta_add_both_ways")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type VectorMt = { __add: (Vector, number) -> Vector }
@@ -1165,7 +1165,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "meta_add_both_ways")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "meta_add_both_ways_lti")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local vectorMt = {}
@@ -1523,7 +1523,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "found_multiple_like_keys")
 TEST_CASE_FIXTURE(BuiltinsFixture, "dont_suggest_exact_match_keys")
 {
     // CLI-114977 Unsealed table writes don't account for order properly
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t = {}
@@ -1566,7 +1566,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "getmetatable_returns_pointer_to_metatable")
 TEST_CASE_FIXTURE(BuiltinsFixture, "metatable_mismatch_should_fail")
 {
     // This test is invalid because we now create a new type state for t1 at the assignment.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t1 = {x = 1}
@@ -1610,7 +1610,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "property_lookup_through_tabletypevar_metatab
 TEST_CASE_FIXTURE(BuiltinsFixture, "missing_metatable_for_sealed_tables_do_not_get_inferred")
 {
     // This test is invalid because we now create a new type state for t at the assignment.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local t = {x = 1}
@@ -1665,7 +1665,7 @@ TEST_CASE_FIXTURE(Fixture, "right_table_missing_key")
 TEST_CASE_FIXTURE(Fixture, "right_table_missing_key2")
 {
     // CLI-114792 We don't report MissingProperties
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(t: {}): { [string]: string, a: string }
@@ -1698,7 +1698,7 @@ TEST_CASE_FIXTURE(Fixture, "casting_unsealed_tables_with_props_into_table_with_i
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("{ [string]: string }", toString(tm->wantedType, o));
         CHECK_EQ("{ [string]: number }", toString(tm->givenType, o));
@@ -1726,7 +1726,7 @@ TEST_CASE_FIXTURE(Fixture, "casting_sealed_tables_with_props_into_table_with_ind
     ToStringOptions o{/* exhaustive= */ true};
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("{ [string]: string }", toString(tm->wantedType, o));
         CHECK_EQ("{ foo: number }", toString(tm->givenType, o));
@@ -1761,7 +1761,7 @@ TEST_CASE_FIXTURE(Fixture, "casting_tables_with_props_into_table_with_indexer3")
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("string" == toString(tm->wantedType));
         CHECK("number" == toString(tm->givenType));
@@ -1796,7 +1796,7 @@ TEST_CASE_FIXTURE(Fixture, "table_subtyping_with_missing_props_dont_report_multi
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             "Type pack '{ x: number }' could not be converted into '{ x: number, y: number, z: number }';"
@@ -1825,7 +1825,7 @@ TEST_CASE_FIXTURE(Fixture, "table_subtyping_with_missing_props_dont_report_multi
         local t: MixedTable = {"fail"}
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 
@@ -1864,7 +1864,7 @@ TEST_CASE_FIXTURE(Fixture, "table_subtyping_with_extra_props_dont_report_multipl
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("{{ x: number }}", toString(tm->wantedType));
         CHECK_EQ("{{ x: number, y: number, z: number }}", toString(tm->givenType));
@@ -1902,7 +1902,7 @@ TEST_CASE_FIXTURE(Fixture, "type_mismatch_on_massive_table_is_cut_short")
     TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
     REQUIRE(tm);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("{ a: number, b: number, c: number, d: number, e: number, ... 1 more ... }" == toString(requireType("t")));
         CHECK_EQ("number", toString(tm->givenType));
@@ -1927,7 +1927,7 @@ TEST_CASE_FIXTURE(Fixture, "type_mismatch_on_massive_table_is_cut_short")
 TEST_CASE_FIXTURE(Fixture, "ok_to_set_nil_even_on_non_lvalue_base_expr")
 {
     // CLI-100076 Assigning nil to an indexer should always succeed
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f(): { [string]: number }
@@ -1949,7 +1949,7 @@ TEST_CASE_FIXTURE(Fixture, "ok_to_provide_a_subtype_during_construction")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114134 Use egraphs to simplify types more consistently
         CHECK("{number | number | string}" == toString(requireType("t"), {/*exhaustive*/ true}));
@@ -1969,7 +1969,7 @@ TEST_CASE_FIXTURE(Fixture, "reasonable_error_when_adding_a_nonexistent_property_
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CannotExtendTable* cet = get<CannotExtendTable>(result.errors[0]);
         REQUIRE_MESSAGE(cet, "Expected CannotExtendTable but got " << result.errors[0]);
@@ -2013,7 +2013,7 @@ TEST_CASE_FIXTURE(Fixture, "only_ascribe_synthetic_names_at_module_scope")
 
     CHECK_EQ("TopLevel", toString(requireType("TopLevel")));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{number}?", toString(requireType("foo")));
     else
         CHECK_EQ("{number}", toString(requireType("foo")));
@@ -2037,7 +2037,7 @@ TEST_CASE_FIXTURE(Fixture, "hide_table_error_properties")
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("Cannot add property 'a' to table '{ x: number }'", toString(result.errors[0]));
         CHECK_EQ("Cannot add property 'b' to table '{ x: number }'", toString(result.errors[1]));
@@ -2096,7 +2096,7 @@ local Test: {Table} = {
 TEST_CASE_FIXTURE(Fixture, "common_table_element_general")
 {
     // CLI-115275 - Bidirectional inference does not always propagate indexer types into the expression
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Table = {
@@ -2218,7 +2218,7 @@ foo({
 TEST_CASE_FIXTURE(Fixture, "common_table_element_union_in_call_tail")
 {
     // CLI-115239 - Bidirectional checking does not work for __call metamethods
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Foo = {x: number | string}
@@ -2265,7 +2265,7 @@ TEST_CASE_FIXTURE(Fixture, "invariant_table_properties_means_instantiating_table
         local c : string = t.m("hi")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
 
@@ -2320,7 +2320,7 @@ local b: B = a
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == R"(Type 'A' could not be converted into 'B'; at [read "y"], number is not exactly string)");
     else
     {
@@ -2347,7 +2347,7 @@ local b: B = a
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors.at(0)) == R"(Type 'A' could not be converted into 'B'; at [read "b"][read "y"], number is not exactly string)");
     else
     {
@@ -2396,7 +2396,7 @@ Type
 could not be converted into
     '<a>(a) -> ()'; different number of generic type parameters)";
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // The assignment of c2 to b2 is, surprisingly, allowed under the new
         // solver for two reasons:
@@ -2461,7 +2461,7 @@ TEST_CASE_FIXTURE(Fixture, "error_detailed_indexer_key")
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("Type 'A' could not be converted into 'B'; at indexer(), number is not exactly string" == toString(result.errors[0]));
     }
@@ -2487,7 +2487,7 @@ TEST_CASE_FIXTURE(Fixture, "error_detailed_indexer_value")
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("Type 'A' could not be converted into 'B'; at indexResult(), number is not exactly string" == toString(result.errors[0]));
     }
@@ -2504,7 +2504,7 @@ Type 'number' could not be converted into 'string' in an invariant context)";
 TEST_CASE_FIXTURE(Fixture, "explicitly_typed_table")
 {
     // Table properties like HasSuper.p must be invariant.  The new solver rightly rejects this program.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 --!strict
@@ -2536,7 +2536,7 @@ local y: number = tmp.p.y
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(
             "Type 'tmp' could not be converted into 'HasSuper'; at [read \"p\"], { x: number, y: number } is not exactly Super" ==
             toString(result.errors[0])
@@ -2554,7 +2554,7 @@ Table type '{ x: number, y: number }' not compatible with type 'Super' because t
 TEST_CASE_FIXTURE(Fixture, "explicitly_typed_table_with_indexer")
 {
     // CLI-114791 Bidirectional inference should be able to cause the inference engine to forget that a table literal has some property
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -2572,7 +2572,7 @@ TEST_CASE_FIXTURE(Fixture, "explicitly_typed_table_with_indexer")
 TEST_CASE_FIXTURE(BuiltinsFixture, "recursive_metatable_type_call")
 {
     // CLI-114782
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local b
@@ -2704,7 +2704,7 @@ TEST_CASE_FIXTURE(Fixture, "confusing_indexing")
         local foo = f({p = "string"})
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114781 Bidirectional checking can't see through the intersection
         LUAU_REQUIRE_ERROR_COUNT(1, result);
@@ -2730,7 +2730,7 @@ TEST_CASE_FIXTURE(Fixture, "pass_a_union_of_tables_to_a_function_that_requires_a
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         REQUIRE_EQ("{ y: number }", toString(requireType("b")));
     else
         REQUIRE_EQ("{- y: number -}", toString(requireType("b")));
@@ -2751,7 +2751,7 @@ TEST_CASE_FIXTURE(Fixture, "pass_a_union_of_tables_to_a_function_that_requires_a
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         REQUIRE_EQ("{ y: number }", toString(requireType("b")));
     else
         REQUIRE_EQ("{- y: number -}", toString(requireType("b")));
@@ -2827,7 +2827,7 @@ TEST_CASE_FIXTURE(Fixture, "table_length")
 TEST_CASE_FIXTURE(Fixture, "nil_assign_doesnt_hit_indexer")
 {
     // CLI-100076 - Assigning a table key to `nil` in the presence of an indexer should always be permitted
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check("local a = {} a[0] = 7  a[0] = nil");
     LUAU_REQUIRE_ERROR_COUNT(0, result);
@@ -2933,7 +2933,7 @@ TEST_CASE_FIXTURE(Fixture, "tables_get_names_from_their_locals")
 TEST_CASE_FIXTURE(Fixture, "should_not_unblock_table_type_twice")
 {
     // don't run this when the DCR flag isn't set
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     check(R"(
@@ -2973,7 +2973,7 @@ TEST_CASE_FIXTURE(Fixture, "generalize_table_argument")
     const TableType* fooArg1Table = get<TableType>(follow(*fooArg1));
     REQUIRE(fooArg1Table);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(fooArg1Table->state, TableState::Sealed);
     else
         CHECK_EQ(fooArg1Table->state, TableState::Generic);
@@ -3059,7 +3059,7 @@ TEST_CASE_FIXTURE(Fixture, "inferring_crazy_table_should_also_be_quick")
     )");
 
     ModulePtr module = getMainModule();
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_GE(500, module->internalTypes.types.size());
     else
         CHECK_GE(100, module->internalTypes.types.size());
@@ -3119,7 +3119,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dont_crash_when_setmetatable_does_not_produc
 {
     CheckResult result = check("local x = setmetatable({})");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-114665: Generic parameters should not also be optional.
         LUAU_REQUIRE_NO_ERRORS(result);
@@ -3224,7 +3224,7 @@ local baz = foo[bar]
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "table_call_metamethod_basic")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -3239,7 +3239,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_call_metamethod_basic")
         local foo = a(12)
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK(get<ExplicitFunctionAnnotationRecommended>(result.errors[0]));
@@ -3261,7 +3261,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_call_metamethod_must_be_callable")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         if (DFFlag::LuauImproveNonFunctionCallError)
             CHECK("Cannot call a value of type a" == toString(result.errors[0]));
@@ -3300,7 +3300,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "table_call_metamethod_generic")
 TEST_CASE_FIXTURE(BuiltinsFixture, "table_simple_call")
 {
     // The new solver can see that this function is safe to oversaturate.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a = setmetatable({ x = 2 }, {
@@ -3334,7 +3334,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "access_index_metamethod_that_returns_variadi
 
     ToStringOptions o;
     o.exhaustive = true;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ x: string }", toString(requireType("foo"), o));
     else
         CHECK_EQ("{| x: string |}", toString(requireType("foo"), o));
@@ -3386,7 +3386,7 @@ TEST_CASE_FIXTURE(Fixture, "checked_prop_too_early")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("Value of type '{ x: number? }?' could be nil", toString(result.errors[0]));
         CHECK_EQ("number | { x: number }", toString(requireType("u")));
@@ -3406,7 +3406,7 @@ TEST_CASE_FIXTURE(Fixture, "accidentally_checked_prop_in_opposite_branch")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("Value of type '{ x: number? }?' could be nil", toString(result.errors[0]));
     else
         CHECK_EQ("Value of type '{| x: number? |}?' could be nil", toString(result.errors[0]));
@@ -3485,7 +3485,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "dont_leak_free_table_props")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("({ read blah: unknown }) -> ()", toString(requireType("a")));
         CHECK_EQ("({ read gwar: unknown }) -> ()", toString(requireType("b")));
@@ -3505,7 +3505,7 @@ TEST_CASE_FIXTURE(Fixture, "mixed_tables_with_implicit_numbered_keys")
         local t: { [string]: number } = { 5, 6, 7 }
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK(
@@ -3572,7 +3572,7 @@ TEST_CASE_FIXTURE(Fixture, "prop_access_on_unions_of_indexers_where_key_whose_ty
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("Type '{ [boolean]: number } | {number}' does not have key 'x'", toString(result.errors[0]));
     else
         CHECK_EQ("Type '{number} | {| [boolean]: number |}' does not have key 'x'", toString(result.errors[0]));
@@ -3593,7 +3593,7 @@ local b = a.x
 TEST_CASE_FIXTURE(Fixture, "scalar_is_a_subtype_of_a_compatible_polymorphic_shape_type")
 {
     // CLI-115087 The new solver cannot infer that a table-like type is actually string
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f(s)
@@ -3620,7 +3620,7 @@ TEST_CASE_FIXTURE(Fixture, "scalar_is_not_a_subtype_of_a_compatible_polymorphic_
         f("baz" :: "bar" | "baz")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // CLI-115090 Error reporting is quite bad in this case.
 
@@ -3682,7 +3682,7 @@ Table type 'typeof(string)' not compatible with type 't1 where t1 = {- absolutel
 TEST_CASE_FIXTURE(Fixture, "a_free_shape_can_turn_into_a_scalar_if_it_is_compatible")
 {
     // CLI-115087 The new solver cannot infer that a table-like type is actually string
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function f(s): string
@@ -3704,7 +3704,7 @@ TEST_CASE_FIXTURE(Fixture, "a_free_shape_cannot_turn_into_a_scalar_if_it_is_not_
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(4, result);
 
@@ -3737,7 +3737,7 @@ Table type 'typeof(string)' not compatible with type 't1 where t1 = {+ absolutel
 TEST_CASE_FIXTURE(BuiltinsFixture, "a_free_shape_can_turn_into_a_scalar_directly")
 {
     // We need egraphs to simplify the type of `out` here.  CLI-114134
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function stringByteList(str)
@@ -3775,7 +3775,7 @@ TEST_CASE_FIXTURE(Fixture, "invariant_table_properties_means_instantiating_table
         local c : string = t.m("hi")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // FIXME.  We really should be reporting just one error in this case.  CLI-114509
         LUAU_REQUIRE_ERROR_COUNT(3, result);
@@ -3813,7 +3813,7 @@ local g : ({ p : number, q : string }) -> ({ p : number, r : boolean }) = f
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         const TypeMismatch* error = get<TypeMismatch>(result.errors[0]);
         REQUIRE_MESSAGE(error, "Expected TypeMismatch but got " << result.errors[0]);
@@ -3833,7 +3833,7 @@ local g : ({ p : number, q : string }) -> ({ p : number, r : boolean }) = f
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "setmetatable_has_a_side_effect")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -3971,7 +3971,7 @@ TEST_CASE_FIXTURE(Fixture, "when_augmenting_an_unsealed_table_with_an_indexer_ap
     CHECK(tt->props.empty());
     REQUIRE(tt->indexer);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("unknown" == toString(tt->indexer->indexType));
     else
         CHECK("string" == toString(tt->indexer->indexType));
@@ -3999,7 +3999,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_extend_unsealed_tables_in_rvalue_position")
 
     CHECK(0 == ttv->props.count(""));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_ERROR_COUNT(1, result);
     else
         LUAU_REQUIRE_NO_ERRORS(result);
@@ -4152,7 +4152,7 @@ TEST_CASE_FIXTURE(Fixture, "cli_84607_missing_prop_in_array_or_dict")
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         const TypeMismatch* err1 = get<TypeMismatch>(result.errors[0]);
         REQUIRE_MESSAGE(err1, "Expected TypeMismatch but got " << result.errors[0]);
@@ -4200,7 +4200,7 @@ TEST_CASE_FIXTURE(Fixture, "simple_method_definition")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ m: (unknown) -> number }", toString(getMainModule()->returnType, ToStringOptions{true}));
     else
         CHECK_EQ("{| m: <a>(a) -> number |}", toString(getMainModule()->returnType, ToStringOptions{true}));
@@ -4208,7 +4208,7 @@ TEST_CASE_FIXTURE(Fixture, "simple_method_definition")
 
 TEST_CASE_FIXTURE(Fixture, "identify_all_problematic_table_fields")
 {
-    ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff_LuauSolverV2{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type T = {
@@ -4236,7 +4236,7 @@ TEST_CASE_FIXTURE(Fixture, "identify_all_problematic_table_fields")
 TEST_CASE_FIXTURE(Fixture, "read_and_write_only_table_properties_are_unsupported")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     CheckResult result = check(R"(
@@ -4276,7 +4276,7 @@ TEST_CASE_FIXTURE(Fixture, "read_ond_write_only_indexers_are_unsupported")
 
 TEST_CASE_FIXTURE(Fixture, "infer_write_property")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(t)
@@ -4308,7 +4308,7 @@ TEST_CASE_FIXTURE(Fixture, "table_subtyping_error_suppression")
 
     // the new solver reports specifically the inner mismatch, rather than the whole table
     // honestly not sure which of these is a better developer experience.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(*tm->wantedType, *builtinTypes->stringType);
         CHECK_EQ(*tm->givenType, *builtinTypes->numberType);
@@ -4322,7 +4322,7 @@ TEST_CASE_FIXTURE(Fixture, "table_subtyping_error_suppression")
 
 TEST_CASE_FIXTURE(Fixture, "write_to_read_only_property")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(t: {read x: number})
@@ -4344,7 +4344,7 @@ TEST_CASE_FIXTURE(Fixture, "write_to_read_only_property")
 
 TEST_CASE_FIXTURE(Fixture, "write_to_unusually_named_read_only_property")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(t: {read ["hello world"]: number})
@@ -4359,7 +4359,7 @@ TEST_CASE_FIXTURE(Fixture, "write_to_unusually_named_read_only_property")
 
 TEST_CASE_FIXTURE(Fixture, "write_annotations_are_unsupported_even_with_the_new_solver")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         function f(t: {write foo: number})
@@ -4374,7 +4374,7 @@ TEST_CASE_FIXTURE(Fixture, "write_annotations_are_unsupported_even_with_the_new_
 
 TEST_CASE_FIXTURE(Fixture, "read_and_write_only_table_properties_are_unsupported")
 {
-    ScopedFastFlag sff[] = {{FFlag::DebugLuauDeferredConstraintResolution, false}};
+    ScopedFastFlag sff[] = {{FFlag::LuauSolverV2, false}};
 
     CheckResult result = check(R"(
         type W = {read x: number}
@@ -4398,7 +4398,7 @@ TEST_CASE_FIXTURE(Fixture, "read_and_write_only_table_properties_are_unsupported
 
 TEST_CASE_FIXTURE(Fixture, "read_ond_write_only_indexers_are_unsupported")
 {
-    ScopedFastFlag sff[] = {{FFlag::DebugLuauDeferredConstraintResolution, false}};
+    ScopedFastFlag sff[] = {{FFlag::LuauSolverV2, false}};
 
     CheckResult result = check(R"(
         type T = {read [string]: number}
@@ -4415,10 +4415,10 @@ TEST_CASE_FIXTURE(Fixture, "read_ond_write_only_indexers_are_unsupported")
 
 TEST_CASE_FIXTURE(Fixture, "table_writes_introduce_write_properties")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
-    ScopedFastFlag sff[] = {{FFlag::DebugLuauDeferredConstraintResolution, true}};
+    ScopedFastFlag sff[] = {{FFlag::LuauSolverV2, true}};
 
     CheckResult result = check(R"(
         function oc(player, speaker)
@@ -4474,7 +4474,7 @@ TEST_CASE_FIXTURE(Fixture, "refined_thing_can_be_an_array")
 
 TEST_CASE_FIXTURE(Fixture, "parameter_was_set_an_indexer_and_bounded_by_string")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -4493,7 +4493,7 @@ TEST_CASE_FIXTURE(Fixture, "parameter_was_set_an_indexer_and_bounded_by_string")
 
 TEST_CASE_FIXTURE(Fixture, "parameter_was_set_an_indexer_and_bounded_by_another_parameter")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -4512,7 +4512,7 @@ TEST_CASE_FIXTURE(Fixture, "parameter_was_set_an_indexer_and_bounded_by_another_
 
 TEST_CASE_FIXTURE(Fixture, "write_to_union_property_not_all_present")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         type Animal = {tag: "Cat", meow: boolean} | {tag: "Dog", woof: boolean}
@@ -4632,7 +4632,7 @@ TEST_CASE_FIXTURE(Fixture, "cant_index_this")
 
 TEST_CASE_FIXTURE(Fixture, "setindexer_multiple_tables_intersection")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function f(t: { [string]: number } & { [thread]: boolean }, x)
@@ -4658,7 +4658,7 @@ TEST_CASE_FIXTURE(Fixture, "insert_a_and_f_of_a_into_table_res_in_a_loop")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK(get<FunctionExitsWithoutReturning>(result.errors[0]));
@@ -4678,7 +4678,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "ipairs_adds_an_unbounded_indexer")
 
     // The old solver erroneously leaves a free type dangling here.  The new
     // solver does better.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("{unknown}" == toString(requireType("a"), {true}));
     else
         CHECK("{a}" == toString(requireType("a"), {true}));
@@ -4808,7 +4808,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "indexing_branching_table")
     LUAU_REQUIRE_NO_ERRORS(result);
 
     // unfortunate type duplication in the union
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("number | string | string" == toString(requireType("test2")));
     else
         CHECK("number | string" == toString(requireType("test2")));
@@ -4826,7 +4826,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "indexing_branching_table2")
     LUAU_REQUIRE_NO_ERRORS(result);
 
     // unfortunate type duplication in the union
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("unknown | unknown" == toString(requireType("test2")));
     else
         CHECK("any" == toString(requireType("test2")));

tests/TypeInfer.test.cpp

@@ -17,7 +17,7 @@
 #include <algorithm>
 
 LUAU_FASTFLAG(LuauFixLocationSpanTableIndexExpr);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauInstantiateInSubtyping);
 LUAU_FASTINT(LuauCheckRecursionLimit);
 LUAU_FASTINT(LuauNormalizeCacheLimit);
@@ -49,7 +49,7 @@ TEST_CASE_FIXTURE(Fixture, "tc_error")
 {
     CheckResult result = check("local a = 7   local b = 'hi'   a = b");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK("number | string" == toString(requireType("a")));
@@ -69,7 +69,7 @@ TEST_CASE_FIXTURE(Fixture, "tc_error_2")
 {
     CheckResult result = check("local a = 7   a = 'hi'");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_NO_ERRORS(result);
         CHECK("number | string" == toString(requireType("a")));
@@ -96,7 +96,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_locals_with_nil_value")
     CheckResult result = check("local f = nil; f = 'hello world'");
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("string?" == toString(requireType("f")));
     }
@@ -128,7 +128,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_locals_via_assignment_from_its_call_site")
         f("foo")
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("unknown" == toString(requireType("a")));
         CHECK("(unknown) -> ()" == toString(requireType("f")));
@@ -146,7 +146,7 @@ TEST_CASE_FIXTURE(Fixture, "infer_locals_via_assignment_from_its_call_site")
 TEST_CASE_FIXTURE(Fixture, "infer_in_nocheck_mode")
 {
     ScopedFastFlag sff[]{
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     CheckResult result = check(R"(
@@ -194,7 +194,7 @@ TEST_CASE_FIXTURE(Fixture, "if_statement")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK("string?" == toString(requireType("a")));
         CHECK("number?" == toString(requireType("b")));
@@ -224,7 +224,7 @@ TEST_CASE_FIXTURE(Fixture, "statements_are_topologically_sorted")
 
 TEST_CASE_FIXTURE(Fixture, "unify_nearly_identical_recursive_types")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local o
@@ -265,7 +265,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "weird_case")
 
 TEST_CASE_FIXTURE(Fixture, "dont_ice_when_failing_the_occurs_check")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -318,7 +318,7 @@ TEST_CASE_FIXTURE(Fixture, "type_errors_infer_types")
     CHECK_EQ("x", err->key);
 
     // TODO: Should we assert anything about these tests when DCR is being used?
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
     {
         CHECK_EQ("*error-type*", toString(requireType("c")));
         CHECK_EQ("*error-type*", toString(requireType("d")));
@@ -384,7 +384,7 @@ TEST_CASE_FIXTURE(Fixture, "exponential_blowup_from_copying_types")
 // checker. We also want it to somewhat match up with production values, so we push up the parser recursion limit a little bit instead.
 TEST_CASE_FIXTURE(Fixture, "check_type_infer_recursion_count")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
 #if defined(LUAU_ENABLE_ASAN)
     int limit = 250;
@@ -442,7 +442,7 @@ TEST_CASE_FIXTURE(Fixture, "check_expr_recursion_limit")
 TEST_CASE_FIXTURE(Fixture, "globals")
 {
     // The new solver does not permit assignments to globals like this.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -456,7 +456,7 @@ TEST_CASE_FIXTURE(Fixture, "globals")
 
 TEST_CASE_FIXTURE(Fixture, "globals2")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!nonstrict
@@ -506,7 +506,7 @@ TEST_CASE_FIXTURE(Fixture, "correctly_scope_locals_do")
 
 TEST_CASE_FIXTURE(Fixture, "checking_should_not_ice")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CHECK_NOTHROW(check(R"(
         --!nonstrict
@@ -600,7 +600,7 @@ TEST_CASE_FIXTURE(Fixture, "tc_after_error_recovery_no_assert")
 TEST_CASE_FIXTURE(BuiltinsFixture, "tc_after_error_recovery_no_replacement_name_in_error")
 {
     {
-        ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+        ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
         CheckResult result = check(R"(
             --!strict
@@ -622,7 +622,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "tc_after_error_recovery_no_replacement_name_
     }
 
     {
-        ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+        ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
         CheckResult result = check(R"(
             --!strict
@@ -697,7 +697,7 @@ TEST_CASE_FIXTURE(Fixture, "cli_39932_use_unifier_in_ensure_methods")
 
 TEST_CASE_FIXTURE(Fixture, "dont_report_type_errors_within_an_AstStatError")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         foo
@@ -708,7 +708,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_report_type_errors_within_an_AstStatError")
 
 TEST_CASE_FIXTURE(Fixture, "dont_report_type_errors_within_an_AstExprError")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a = foo:
@@ -759,7 +759,7 @@ TEST_CASE_FIXTURE(Fixture, "no_stack_overflow_from_isoptional")
     std::optional<TypeId> t0 = lookupType("t0");
     REQUIRE(t0);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("any" == toString(*t0));
     else
         CHECK_EQ("*error-type*", toString(*t0));
@@ -819,7 +819,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "no_heap_use_after_free_error")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         LUAU_REQUIRE_NO_ERRORS(result);
     else
         LUAU_REQUIRE_ERRORS(result);
@@ -1099,7 +1099,7 @@ end
 
 TEST_CASE_FIXTURE(Fixture, "cli_50041_committing_txnlog_in_apollo_client_error")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         --!strict
@@ -1177,7 +1177,7 @@ TEST_CASE_FIXTURE(Fixture, "type_infer_recursion_limit_no_ice")
 
     LUAU_REQUIRE_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Type contains a self-recursive construct that cannot be resolved" == toString(result.errors[0]));
     else
         CHECK_EQ("Code is too complex to typecheck! Consider simplifying the code around this area", toString(result.errors[0]));
@@ -1199,7 +1199,7 @@ TEST_CASE_FIXTURE(Fixture, "type_infer_recursion_limit_normalizer")
 
     CHECK(1 == result.errors.size());
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(Location{{3, 22}, {3, 42}} == result.errors[0].location);
     else
         CHECK(Location{{3, 12}, {3, 46}} == result.errors[0].location);
@@ -1222,7 +1222,7 @@ TEST_CASE_FIXTURE(Fixture, "type_infer_cache_limit_normalizer")
 TEST_CASE_FIXTURE(Fixture, "follow_on_new_types_in_substitution")
 {
     // CLI-114134
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local obj = {}
@@ -1358,7 +1358,7 @@ end
 TEST_CASE_FIXTURE(Fixture, "dcr_delays_expansion_of_function_containing_blocked_parameter_type")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
     };
 
     CheckResult result = check(R"(
@@ -1392,7 +1392,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "recursive_function_that_invokes_itself_with_
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(unknown) -> ()" == toString(requireType("readValue")));
     else
         CHECK("<a>(a) -> ()" == toString(requireType("readValue")));
@@ -1408,7 +1408,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "recursive_function_that_invokes_itself_with_
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("(unknown) -> ()" == toString(requireType("readValue")));
     else
         CHECK("(number) -> ()" == toString(requireType("readValue")));
@@ -1527,7 +1527,7 @@ TEST_CASE_FIXTURE(Fixture, "promote_tail_type_packs")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "lti_must_record_contributing_locations")
 {
-    ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff_LuauSolverV2{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function f(a)
@@ -1563,7 +1563,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "lti_must_record_contributing_locations")
  */
 TEST_CASE_FIXTURE(BuiltinsFixture, "be_sure_to_use_active_txnlog_when_evaluating_a_variadic_overload")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local function concat<T>(target: {T}, ...: {T} | T): {T}
@@ -1615,7 +1615,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "bad_iter_metamethod")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 

tests/TypeInfer.tryUnify.test.cpp

@@ -11,13 +11,13 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauUnifierRecursionOnRestart);
 
 struct TryUnifyFixture : Fixture
 {
     // Cannot use `TryUnifyFixture` under DCR.
-    ScopedFastFlag noDcr{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag noDcr{FFlag::LuauSolverV2, false};
 
     TypeArena arena;
     ScopePtr globalScope{new Scope{arena.addTypePack({TypeId{}})}};
@@ -154,7 +154,7 @@ TEST_CASE_FIXTURE(Fixture, "uninhabited_intersection_sub_anything")
 
 TEST_CASE_FIXTURE(Fixture, "uninhabited_table_sub_never")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(arg : { prop : string & number }) : never
@@ -166,7 +166,7 @@ TEST_CASE_FIXTURE(Fixture, "uninhabited_table_sub_never")
 
 TEST_CASE_FIXTURE(Fixture, "uninhabited_table_sub_anything")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(arg : { prop : string & number }) : boolean
@@ -178,7 +178,7 @@ TEST_CASE_FIXTURE(Fixture, "uninhabited_table_sub_anything")
 
 TEST_CASE_FIXTURE(Fixture, "members_of_failed_typepack_unification_are_unified_with_errorType")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(arg: number) end
@@ -195,7 +195,7 @@ TEST_CASE_FIXTURE(Fixture, "members_of_failed_typepack_unification_are_unified_w
 
 TEST_CASE_FIXTURE(Fixture, "result_of_failed_typepack_unification_is_constrained")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(arg: number) return arg end
@@ -278,7 +278,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "cli_41095_concat_log_in_sealed_table_unifica
 
     LUAU_REQUIRE_ERROR_COUNT(2, result);
     CHECK_EQ(toString(result.errors[0]), "No overload for function accepts 0 arguments.");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(result.errors[1]), "Available overloads: <V>({V}, V) -> (); and <V>({V}, number, V) -> ()");
     else
         CHECK_EQ(toString(result.errors[1]), "Available overloads: ({a}, a) -> (); and ({a}, number, a) -> ()");

tests/TypeInfer.typePacks.test.cpp

@@ -9,7 +9,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauInstantiateInSubtyping);
 
 TEST_SUITE_BEGIN("TypePackTests");
@@ -316,7 +316,7 @@ local c: Packed<string, number, boolean>
     tf = lookupType("Packed");
     REQUIRE(tf);
     CHECK_EQ(toString(*tf), "Packed<T, U...>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(*tf, {true}), "{ f: (T, U...) -> (T, U...) }");
     else
         CHECK_EQ(toString(*tf, {true}), "{| f: (T, U...) -> (T, U...) |}");
@@ -324,7 +324,7 @@ local c: Packed<string, number, boolean>
     auto ttvA = get<TableType>(requireType("a"));
     REQUIRE(ttvA);
     CHECK_EQ(toString(requireType("a")), "Packed<number>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireType("a"), {true}), "{ f: (number) -> number }");
     else
         CHECK_EQ(toString(requireType("a"), {true}), "{| f: (number) -> number |}");
@@ -336,7 +336,7 @@ local c: Packed<string, number, boolean>
     auto ttvB = get<TableType>(requireType("b"));
     REQUIRE(ttvB);
     CHECK_EQ(toString(requireType("b")), "Packed<string, number>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireType("b"), {true}), "{ f: (string, number) -> (string, number) }");
     else
         CHECK_EQ(toString(requireType("b"), {true}), "{| f: (string, number) -> (string, number) |}");
@@ -348,7 +348,7 @@ local c: Packed<string, number, boolean>
     auto ttvC = get<TableType>(requireType("c"));
     REQUIRE(ttvC);
     CHECK_EQ(toString(requireType("c")), "Packed<string, number, boolean>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireType("c"), {true}), "{ f: (string, number, boolean) -> (string, number, boolean) }");
     else
         CHECK_EQ(toString(requireType("c"), {true}), "{| f: (string, number, boolean) -> (string, number, boolean) |}");
@@ -381,7 +381,7 @@ local d: { a: typeof(c) }
     REQUIRE(tf);
     CHECK_EQ(toString(*tf), "Packed<T, U...>");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(toString(*tf, {true}), "{ a: T, b: (U...) -> () }");
 
@@ -421,12 +421,12 @@ type C<X...> = Import.Packed<string, (number, X...)>
     auto tf = lookupType("Alias");
     REQUIRE(tf);
     CHECK_EQ(toString(*tf), "Alias<S, T, R...>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(*tf, {true}), "{ a: S, b: (T, R...) -> () }");
     else
         CHECK_EQ(toString(*tf, {true}), "{| a: S, b: (T, R...) -> () |}");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(requireType("a"), {true}), "{ a: string, b: (number, boolean) -> () }");
     else
         CHECK_EQ(toString(requireType("a"), {true}), "{| a: string, b: (number, boolean) -> () |}");
@@ -434,7 +434,7 @@ type C<X...> = Import.Packed<string, (number, X...)>
     tf = lookupType("B");
     REQUIRE(tf);
     CHECK_EQ(toString(*tf), "B<X...>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(*tf, {true}), "{ a: string, b: (X...) -> () }");
     else
         CHECK_EQ(toString(*tf, {true}), "{| a: string, b: (X...) -> () |}");
@@ -442,7 +442,7 @@ type C<X...> = Import.Packed<string, (number, X...)>
     tf = lookupType("C");
     REQUIRE(tf);
     CHECK_EQ(toString(*tf), "C<X...>");
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(*tf, {true}), "{ a: string, b: (number, X...) -> () }");
     else
         CHECK_EQ(toString(*tf, {true}), "{| a: string, b: (number, X...) -> () |}");
@@ -787,7 +787,7 @@ local d: Y<number, string, ...boolean, ...() -> ()>
 
 TEST_CASE_FIXTURE(Fixture, "type_alias_default_type_errors")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Y<T = T> = { a: T }
@@ -811,7 +811,7 @@ TEST_CASE_FIXTURE(Fixture, "type_alias_default_type_errors2")
 
 TEST_CASE_FIXTURE(Fixture, "type_alias_default_type_errors3")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Y<T = string, U... = ...string> = { a: (T) -> U... }
@@ -824,7 +824,7 @@ TEST_CASE_FIXTURE(Fixture, "type_alias_default_type_errors3")
 
 TEST_CASE_FIXTURE(Fixture, "type_alias_default_type_errors4")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type Packed<T> = (T) -> T
@@ -935,7 +935,7 @@ type R = { m: F<R> }
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ(toString(*lookupType("R"), {true}), "t1 where t1 = { m: (t1) -> (t1) -> () }");
     else
         CHECK_EQ(toString(*lookupType("R"), {true}), "t1 where t1 = {| m: (t1) -> (t1) -> () |}");
@@ -951,7 +951,7 @@ a = b
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         const std::string expected = 
             "Type\n"
@@ -1065,7 +1065,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "detect_cyclic_typepacks2")
 
 TEST_CASE_FIXTURE(Fixture, "unify_variadic_tails_in_arguments")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function foo(...: string): number
@@ -1094,7 +1094,7 @@ TEST_CASE_FIXTURE(Fixture, "unify_variadic_tails_in_arguments_free")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(
             toString(result.errors.at(0)) ==
             "Type pack '...number' could not be converted into 'boolean'; type ...number.tail() (...number) is not a subtype of boolean (boolean)"
@@ -1106,7 +1106,7 @@ TEST_CASE_FIXTURE(Fixture, "unify_variadic_tails_in_arguments_free")
 TEST_CASE_FIXTURE(BuiltinsFixture, "type_packs_with_tails_in_vararg_adjustment")
 {
     std::optional<ScopedFastFlag> sff;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         sff = {FFlag::LuauInstantiateInSubtyping, true};
 
     CheckResult result = check(R"(
@@ -1127,7 +1127,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_packs_with_tails_in_vararg_adjustment")
 TEST_CASE_FIXTURE(BuiltinsFixture, "generalize_expectedTypes_with_proper_scope")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+        {FFlag::LuauSolverV2, true},
         {FFlag::LuauInstantiateInSubtyping, true},
     };
 

tests/TypeInfer.typestates.test.cpp

@@ -3,7 +3,7 @@
 
 #include "doctest.h"
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 using namespace Luau;
 
@@ -11,7 +11,7 @@ namespace
 {
 struct TypeStateFixture : BuiltinsFixture
 {
-    ScopedFastFlag dcr{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag dcr{FFlag::LuauSolverV2, true};
 };
 } // namespace
 
@@ -73,7 +73,7 @@ TEST_CASE_FIXTURE(TypeStateFixture, "parameter_x_was_constrained_by_two_types")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         // `y` is annotated `string | number` which is explicitly not compatible with `string?`
         // as such, we produce an error here for that mismatch.
@@ -392,7 +392,7 @@ TEST_CASE_FIXTURE(TypeStateFixture, "prototyped_recursive_functions")
 TEST_CASE_FIXTURE(BuiltinsFixture, "prototyped_recursive_functions_but_has_future_assignments")
 {
     // early return if the flag isn't set since this is blocking gated commits
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -461,7 +461,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typestates_preserve_error_suppression_proper
     // early return if the flag isn't set since this is blocking gated commits
     // unconditional return
     // CLI-117098 Type states with error suppressing properties doesn't infer the correct type for properties.
-    if (!FFlag::DebugLuauDeferredConstraintResolution || FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2 || FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -477,7 +477,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typestates_preserve_error_suppression_proper
 TEST_CASE_FIXTURE(BuiltinsFixture, "typestates_do_not_apply_to_the_initial_local_definition")
 {
     // early return if the flag isn't set since this is blocking gated commits
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -495,7 +495,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typestates_do_not_apply_to_the_initial_local
 
 TEST_CASE_FIXTURE(Fixture, "typestate_globals")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     loadDefinition(R"(
         declare foo: string | number
@@ -512,7 +512,7 @@ TEST_CASE_FIXTURE(Fixture, "typestate_globals")
 
 TEST_CASE_FIXTURE(Fixture, "typestate_unknown_global")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         x = 5

tests/TypeInfer.unionTypes.test.cpp

@@ -8,7 +8,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauAcceptIndexingTableUnionsIntersections)
 
 TEST_SUITE_BEGIN("UnionTypes");
@@ -36,7 +36,7 @@ TEST_CASE_FIXTURE(Fixture, "return_types_can_be_disjoint")
 {
     // CLI-114134 We need egraphs to consistently reduce the cyclic union
     // introduced by the increment here.
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local count = 0
@@ -122,7 +122,7 @@ TEST_CASE_FIXTURE(Fixture, "optional_arguments")
 TEST_CASE_FIXTURE(Fixture, "optional_arguments_table")
 {
     // CLI-115588 - Bidirectional inference does not happen for assignments
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         local a:{a:string, b:string?}
@@ -237,7 +237,7 @@ TEST_CASE_FIXTURE(Fixture, "index_on_a_union_type_with_missing_property")
     REQUIRE(mup);
     CHECK_EQ("Key 'x' is missing from 'B' in the type 'A | B'", toString(result.errors[0]));
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(A | B) -> number", toString(requireType("f")));
     else
         CHECK_EQ("(A | B) -> *error-type*", toString(requireType("f")));
@@ -411,7 +411,7 @@ TEST_CASE_FIXTURE(Fixture, "optional_assignment_errors_2")
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
     auto s = toString(result.errors[0]);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("Value of type '({ x: number } & { y: number })?' could be nil", s);
     else
         CHECK_EQ("Value of type '({| x: number |} & {| y: number |})?' could be nil", s);
@@ -473,7 +473,7 @@ end
 
 TEST_CASE_FIXTURE(Fixture, "unify_unsealed_table_union_check")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
 local x = { x = 3 }
@@ -534,7 +534,7 @@ end
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ(
             toString(result.errors[0]),
@@ -566,7 +566,7 @@ TEST_CASE_FIXTURE(Fixture, "error_detailed_union_all")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK(toString(result.errors[0]) == "Type '{ w: number }' could not be converted into 'X | Y | Z'");
     else
         CHECK_EQ(toString(result.errors[0]), R"(Type 'a' could not be converted into 'X | Y | Z'; none of the union options are compatible)");
@@ -581,7 +581,7 @@ local a: X? = { w = 4 }
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK("Type '{ w: number }' could not be converted into 'X?'" == toString(result.errors[0]));
     else
     {
@@ -647,7 +647,7 @@ TEST_CASE_FIXTURE(Fixture, "indexing_into_a_cyclic_union_doesnt_crash")
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "table_union_write_indirect")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         type A = { x: number, y: (number) -> string } | { z: number, y: (number) -> string }
@@ -723,7 +723,7 @@ TEST_CASE_FIXTURE(Fixture, "union_of_generic_typepack_functions")
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_mentioning_generics")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f<a,b>()
@@ -743,7 +743,7 @@ TEST_CASE_FIXTURE(Fixture, "union_of_functions_mentioning_generics")
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_mentioning_generic_typepacks")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f<a...>()
@@ -764,7 +764,7 @@ could not be converted into
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_with_mismatching_arg_arities")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(x : (number) -> number?)
@@ -783,7 +783,7 @@ could not be converted into
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_with_mismatching_result_arities")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(x : () -> (number | string))
@@ -802,7 +802,7 @@ could not be converted into
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_with_variadics")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(x : (...nil) -> (...number?))
@@ -829,7 +829,7 @@ TEST_CASE_FIXTURE(Fixture, "union_of_functions_with_mismatching_arg_variadics")
      )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK(R"(Type
     '(number) -> ()'
@@ -848,7 +848,7 @@ could not be converted into
 
 TEST_CASE_FIXTURE(Fixture, "union_of_functions_with_mismatching_result_variadics")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(x : () -> (number?, ...number))
@@ -867,7 +867,7 @@ could not be converted into
 
 TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_union_types")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -884,7 +884,7 @@ TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_union_types")
 
 TEST_CASE_FIXTURE(Fixture, "less_greedy_unification_with_union_types_2")
 {
-    if (!FFlag::DebugLuauDeferredConstraintResolution)
+    if (!FFlag::LuauSolverV2)
         return;
 
     CheckResult result = check(R"(
@@ -916,7 +916,7 @@ TEST_CASE_FIXTURE(Fixture, "union_table_any_property")
 
 TEST_CASE_FIXTURE(Fixture, "union_function_any_args")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f(sup : ((...any) -> (...any))?, sub : ((number) -> (...any)))
@@ -940,7 +940,7 @@ TEST_CASE_FIXTURE(Fixture, "optional_any")
 
 TEST_CASE_FIXTURE(Fixture, "generic_function_with_optional_arg")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, false};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, false};
 
     CheckResult result = check(R"(
         function f<T>(x : T?) : {T}
@@ -974,7 +974,7 @@ TEST_CASE_FIXTURE(Fixture, "lookup_prop_of_intersection_containing_unions")
 
 TEST_CASE_FIXTURE(Fixture, "suppress_errors_for_prop_lookup_of_a_union_that_includes_error")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     registerHiddenTypes(&frontend);
 

tests/TypeInfer.unknownnever.test.cpp

@@ -6,7 +6,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 
 TEST_SUITE_BEGIN("TypeInferUnknownNever");
 
@@ -118,7 +118,7 @@ TEST_CASE_FIXTURE(Fixture, "type_packs_containing_never_is_itself_uninhabitable"
         local x, y, z = f()
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK("Function only returns 2 values, but 3 are required here" == toString(result.errors[0]));
@@ -149,7 +149,7 @@ TEST_CASE_FIXTURE(Fixture, "type_packs_containing_never_is_itself_uninhabitable2
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CHECK_EQ("string", toString(requireType("x1")));
         CHECK_EQ("never", toString(requireType("x2")));
@@ -199,7 +199,7 @@ TEST_CASE_FIXTURE(Fixture, "assign_to_local_which_is_never")
         t = 3
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
     }
@@ -266,7 +266,7 @@ TEST_CASE_FIXTURE(Fixture, "pick_never_from_variadic_type_pack")
 TEST_CASE_FIXTURE(Fixture, "index_on_union_of_tables_for_properties_that_is_never")
 {
     // CLI-117116 - We are erroneously warning when passing a valid table literal where we expect a union of tables.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         type Disjoint = {foo: never, bar: unknown, tag: "ok"} | {foo: never, baz: unknown, tag: "err"}
@@ -286,7 +286,7 @@ TEST_CASE_FIXTURE(Fixture, "index_on_union_of_tables_for_properties_that_is_neve
 TEST_CASE_FIXTURE(Fixture, "index_on_union_of_tables_for_properties_that_is_sorta_never")
 {
     // CLI-117116 - We are erroneously warning when passing a valid table literal where we expect a union of tables.
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         return;
     CheckResult result = check(R"(
         type Disjoint = {foo: string, bar: unknown, tag: "ok"} | {foo: never, baz: unknown, tag: "err"}
@@ -335,7 +335,7 @@ TEST_CASE_FIXTURE(Fixture, "dont_unify_operands_if_one_of_the_operand_is_never_i
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("(nil, unknown) -> boolean", toString(requireType("ord")));
     else
         CHECK_EQ("<a>(nil, a) -> boolean", toString(requireType("ord")));
@@ -349,7 +349,7 @@ TEST_CASE_FIXTURE(Fixture, "math_operators_and_never")
         end
     )");
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         LUAU_REQUIRE_ERROR_COUNT(1, result);
         CHECK(get<ExplicitFunctionAnnotationRecommended>(result.errors[0]));
@@ -379,7 +379,7 @@ TEST_CASE_FIXTURE(Fixture, "compare_never")
 
 TEST_CASE_FIXTURE(Fixture, "lti_error_at_declaration_for_never_normalizations")
 {
-    ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff_LuauSolverV2{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function num(x: number) end
@@ -403,7 +403,7 @@ TEST_CASE_FIXTURE(Fixture, "lti_error_at_declaration_for_never_normalizations")
 
 TEST_CASE_FIXTURE(Fixture, "lti_permit_explicit_never_annotation")
 {
-    ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff_LuauSolverV2{FFlag::LuauSolverV2, true};
 
     CheckResult result = check(R"(
         local function num(x: number) end

tests/TypePath.test.cpp

@@ -15,17 +15,17 @@
 using namespace Luau;
 using namespace Luau::TypePath;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAG(LuauSolverV2);
 LUAU_DYNAMIC_FASTINT(LuauTypePathMaximumTraverseSteps);
 
 struct TypePathFixture : Fixture
 {
-    ScopedFastFlag sff1{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff1{FFlag::LuauSolverV2, true};
 };
 
 struct TypePathBuiltinsFixture : BuiltinsFixture
 {
-    ScopedFastFlag sff1{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff1{FFlag::LuauSolverV2, true};
 };
 
 TEST_SUITE_BEGIN("TypePathManipulation");
@@ -522,7 +522,7 @@ TEST_SUITE_BEGIN("TypePathToString");
 TEST_CASE("field")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     CHECK(toString(PathBuilder().prop("foo").build()) == R"(["foo"])");
@@ -551,7 +551,7 @@ TEST_CASE("empty_path")
 TEST_CASE("prop")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::DebugLuauDeferredConstraintResolution, false},
+        {FFlag::LuauSolverV2, false},
     };
 
     Path p = PathBuilder().prop("foo").build();
@@ -592,7 +592,7 @@ TEST_CASE("fields")
 
 TEST_CASE("chained")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     CHECK(
         PathBuilder().index(0).readProp("foo").mt().readProp("bar").args().index(1).build() ==

tests/TypeVar.test.cpp

@@ -304,7 +304,7 @@ TEST_CASE_FIXTURE(Fixture, "substitution_skip_failure")
 
     REQUIRE(!anyification.normalizationTooComplex);
     REQUIRE(any.has_value());
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
         CHECK_EQ("{ f: t1 } where t1 = () -> { f: () -> { f: ({ f: t1 }) -> (), signal: { f: (any) -> () } } }", toString(*any));
     else
         CHECK_EQ("{| f: t1 |} where t1 = () -> {| f: () -> {| f: ({| f: t1 |}) -> (), signal: {| f: (any) -> () |} |} |}", toString(*any));

tests/Unifier2.test.cpp

@@ -12,7 +12,7 @@
 
 using namespace Luau;
 
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 struct Unifier2Fixture
 {
@@ -23,7 +23,7 @@ struct Unifier2Fixture
     Unifier2 u2{NotNull{&arena}, NotNull{&builtinTypes}, NotNull{&scope}, NotNull{&iceReporter}};
     ToStringOptions opts;
 
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     std::pair<TypeId, FreeType*> freshType()
     {

tests/VisitType.test.cpp

@@ -9,13 +9,13 @@
 using namespace Luau;
 
 LUAU_FASTINT(LuauVisitRecursionLimit);
-LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
+LUAU_FASTFLAG(LuauSolverV2)
 
 TEST_SUITE_BEGIN("VisitType");
 
 TEST_CASE_FIXTURE(Fixture, "throw_when_limit_is_exceeded")
 {
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    if (FFlag::LuauSolverV2)
     {
         CheckResult result = check(R"(
             local t : {a: {b: {c: {d: {e: boolean}}}}}
@@ -61,7 +61,7 @@ TEST_CASE_FIXTURE(Fixture, "some_free_types_do_not_have_bounds")
 
 TEST_CASE_FIXTURE(Fixture, "some_free_types_have_bounds")
 {
-    ScopedFastFlag sff{FFlag::DebugLuauDeferredConstraintResolution, true};
+    ScopedFastFlag sff{FFlag::LuauSolverV2, true};
 
     Scope scope{builtinTypes->anyTypePack};
     Type t{FreeType{&scope, builtinTypes->neverType, builtinTypes->numberType}};

tools/lldb_formatters.py

@@ -371,7 +371,7 @@ def luau_typepath_property_summary(valobj, internal_dict, options):
     read_write = False
     try:
         fflag_valobj = valobj.GetFrame().GetValueForVariablePath(
-            "FFlag::DebugLuauDeferredConstraintResolution::value")
+            "FFlag::LuauSolverV2::value")
 
         read_write = fflag_valobj.GetValue() == "true"
     except Exception as e:

tools/test_dcr.py

@@ -136,7 +136,7 @@ def main():
 
     failList = loadFailList()
 
-    flags = ["true", "DebugLuauDeferredConstraintResolution"]
+    flags = ["true", "LuauSolverV2"]
 
     commandLine = [args.path, "--reporters=xml", "--fflags=" + ",".join(flags)]