Sync to upstream/release/648 (#1477)

## What's new

* Added `math.map` function to the standard library, based on
https://rfcs.luau-lang.org/function-math-map.html
* `FileResolver` can provide an implementation of
`getRequireSuggestions` to provide auto-complete suggestions for
require-by-string

## New Solver

* In user-defined type functions, `readproperty` and `writeproperty`
will return `nil` instead of erroring if property is not found
* Fixed incorrect scope of variadic arguments in the data-flow graph
* Fixed multiple assertion failures

---

Internal Contributors:

Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>

Analysis/include/Luau/Autocomplete.h

@@ -39,6 +39,7 @@ enum class AutocompleteEntryKind
     Type,
     Module,
     GeneratedFunction,
+    RequirePath,
 };
 
 enum class ParenthesesRecommendation

Analysis/include/Luau/BuiltinDefinitions.h

@@ -9,6 +9,8 @@
 namespace Luau
 {
 
+static constexpr char kRequireTagName[] = "require";
+
 struct Frontend;
 struct GlobalTypes;
 struct TypeChecker;

Analysis/include/Luau/DataFlowGraph.h

@@ -68,7 +68,6 @@ private:
     DenseHashMap<const AstExpr*, const Def*> compoundAssignDefs{nullptr};
 
     DenseHashMap<const AstExpr*, const RefinementKey*> astRefinementKeys{nullptr};
-
     friend struct DataFlowGraphBuilder;
 };
 
@@ -83,6 +82,7 @@ struct DfgScope
 
     DfgScope* parent;
     ScopeType scopeType;
+    Location location;
 
     using Bindings = DenseHashMap<Symbol, const Def*>;
     using Props = DenseHashMap<const Def*, std::unordered_map<std::string, const Def*>>;
@@ -105,10 +105,44 @@ struct DataFlowResult
     const RefinementKey* parent = nullptr;
 };
 
+using ScopeStack = std::vector<DfgScope*>;
+
 struct DataFlowGraphBuilder
 {
     static DataFlowGraph build(AstStatBlock* root, NotNull<struct InternalErrorReporter> handle);
 
+    /**
+     * This method is identical to the build method above, but returns a pair of dfg, scopes as the data flow graph
+     * here is intended to live on the module between runs of typechecking. Before, the DFG only needed to live as
+     * long as the typecheck, but in a world with incremental typechecking, we need the information on the dfg to incrementally
+     * typecheck small fragments of code.
+     * @param block - pointer to the ast to build the dfg for
+     * @param handle - for raising internal errors while building the dfg
+     */
+    static std::pair<std::shared_ptr<DataFlowGraph>, std::vector<std::unique_ptr<DfgScope>>> buildShared(
+        AstStatBlock* block,
+        NotNull<InternalErrorReporter> handle
+    );
+
+    /**
+     * Takes a stale graph along with a list of scopes, a small fragment of the ast, and a cursor position
+     * and constructs the DataFlowGraph for just that fragment. This method will fabricate defs in the final
+     * DFG for things that have been referenced and exist in the stale dfg.
+     * For example, the fragment local z = x + y will populate defs for x and y from the stale graph.
+     * @param staleGraph - the old DFG
+     * @param scopes - the old DfgScopes in the graph
+     * @param fragment - the Ast Fragment to re-build the root for
+     * @param cursorPos - the current location of the cursor - used to determine which scope we are currently in
+     * @param handle - for internal compiler errors
+     */
+    static DataFlowGraph updateGraph(
+        const DataFlowGraph& staleGraph,
+        const std::vector<std::unique_ptr<DfgScope>>& scopes,
+        AstStatBlock* fragment,
+        const Position& cursorPos,
+        NotNull<InternalErrorReporter> handle
+    );
+
 private:
     DataFlowGraphBuilder() = default;
 
@@ -120,10 +154,15 @@ private:
     NotNull<RefinementKeyArena> keyArena{&graph.keyArena};
 
     struct InternalErrorReporter* handle = nullptr;
-    DfgScope* moduleScope = nullptr;
 
+    /// The arena owning all of the scope allocations for the dataflow graph being built.
     std::vector<std::unique_ptr<DfgScope>> scopes;
 
+    /// A stack of scopes used by the visitor to see where we are.
+    ScopeStack scopeStack;
+
+    DfgScope* currentScope();
+
     struct FunctionCapture
     {
         std::vector<DefId> captureDefs;
@@ -134,81 +173,81 @@ private:
     DenseHashMap<Symbol, FunctionCapture> captures{Symbol{}};
     void resolveCaptures();
 
-    DfgScope* childScope(DfgScope* scope, DfgScope::ScopeType scopeType = DfgScope::Linear);
+    DfgScope* makeChildScope(Location loc, DfgScope::ScopeType scopeType = DfgScope::Linear);
 
     void join(DfgScope* p, DfgScope* a, DfgScope* b);
     void joinBindings(DfgScope* p, const DfgScope& a, const DfgScope& b);
     void joinProps(DfgScope* p, const DfgScope& a, const DfgScope& b);
 
-    DefId lookup(DfgScope* scope, Symbol symbol);
-    DefId lookup(DfgScope* scope, DefId def, const std::string& key);
+    DefId lookup(Symbol symbol);
+    DefId lookup(DefId def, const std::string& key);
 
-    ControlFlow visit(DfgScope* scope, AstStatBlock* b);
-    ControlFlow visitBlockWithoutChildScope(DfgScope* scope, AstStatBlock* b);
+    ControlFlow visit(AstStatBlock* b);
+    ControlFlow visitBlockWithoutChildScope(AstStatBlock* b);
 
-    ControlFlow visit(DfgScope* scope, AstStat* s);
-    ControlFlow visit(DfgScope* scope, AstStatIf* i);
-    ControlFlow visit(DfgScope* scope, AstStatWhile* w);
-    ControlFlow visit(DfgScope* scope, AstStatRepeat* r);
-    ControlFlow visit(DfgScope* scope, AstStatBreak* b);
-    ControlFlow visit(DfgScope* scope, AstStatContinue* c);
-    ControlFlow visit(DfgScope* scope, AstStatReturn* r);
-    ControlFlow visit(DfgScope* scope, AstStatExpr* e);
-    ControlFlow visit(DfgScope* scope, AstStatLocal* l);
-    ControlFlow visit(DfgScope* scope, AstStatFor* f);
-    ControlFlow visit(DfgScope* scope, AstStatForIn* f);
-    ControlFlow visit(DfgScope* scope, AstStatAssign* a);
-    ControlFlow visit(DfgScope* scope, AstStatCompoundAssign* c);
-    ControlFlow visit(DfgScope* scope, AstStatFunction* f);
-    ControlFlow visit(DfgScope* scope, AstStatLocalFunction* l);
-    ControlFlow visit(DfgScope* scope, AstStatTypeAlias* t);
-    ControlFlow visit(DfgScope* scope, AstStatTypeFunction* f);
-    ControlFlow visit(DfgScope* scope, AstStatDeclareGlobal* d);
-    ControlFlow visit(DfgScope* scope, AstStatDeclareFunction* d);
-    ControlFlow visit(DfgScope* scope, AstStatDeclareClass* d);
-    ControlFlow visit(DfgScope* scope, AstStatError* error);
+    ControlFlow visit(AstStat* s);
+    ControlFlow visit(AstStatIf* i);
+    ControlFlow visit(AstStatWhile* w);
+    ControlFlow visit(AstStatRepeat* r);
+    ControlFlow visit(AstStatBreak* b);
+    ControlFlow visit(AstStatContinue* c);
+    ControlFlow visit(AstStatReturn* r);
+    ControlFlow visit(AstStatExpr* e);
+    ControlFlow visit(AstStatLocal* l);
+    ControlFlow visit(AstStatFor* f);
+    ControlFlow visit(AstStatForIn* f);
+    ControlFlow visit(AstStatAssign* a);
+    ControlFlow visit(AstStatCompoundAssign* c);
+    ControlFlow visit(AstStatFunction* f);
+    ControlFlow visit(AstStatLocalFunction* l);
+    ControlFlow visit(AstStatTypeAlias* t);
+    ControlFlow visit(AstStatTypeFunction* f);
+    ControlFlow visit(AstStatDeclareGlobal* d);
+    ControlFlow visit(AstStatDeclareFunction* d);
+    ControlFlow visit(AstStatDeclareClass* d);
+    ControlFlow visit(AstStatError* error);
 
-    DataFlowResult visitExpr(DfgScope* scope, AstExpr* e);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprGroup* group);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprLocal* l);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprGlobal* g);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprCall* c);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprIndexName* i);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprIndexExpr* i);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprFunction* f);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprTable* t);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprUnary* u);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprBinary* b);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprTypeAssertion* t);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprIfElse* i);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprInterpString* i);
-    DataFlowResult visitExpr(DfgScope* scope, AstExprError* error);
+    DataFlowResult visitExpr(AstExpr* e);
+    DataFlowResult visitExpr(AstExprGroup* group);
+    DataFlowResult visitExpr(AstExprLocal* l);
+    DataFlowResult visitExpr(AstExprGlobal* g);
+    DataFlowResult visitExpr(AstExprCall* c);
+    DataFlowResult visitExpr(AstExprIndexName* i);
+    DataFlowResult visitExpr(AstExprIndexExpr* i);
+    DataFlowResult visitExpr(AstExprFunction* f);
+    DataFlowResult visitExpr(AstExprTable* t);
+    DataFlowResult visitExpr(AstExprUnary* u);
+    DataFlowResult visitExpr(AstExprBinary* b);
+    DataFlowResult visitExpr(AstExprTypeAssertion* t);
+    DataFlowResult visitExpr(AstExprIfElse* i);
+    DataFlowResult visitExpr(AstExprInterpString* i);
+    DataFlowResult visitExpr(AstExprError* error);
 
-    void visitLValue(DfgScope* scope, AstExpr* e, DefId incomingDef);
-    DefId visitLValue(DfgScope* scope, AstExprLocal* l, DefId incomingDef);
-    DefId visitLValue(DfgScope* scope, AstExprGlobal* g, DefId incomingDef);
-    DefId visitLValue(DfgScope* scope, AstExprIndexName* i, DefId incomingDef);
-    DefId visitLValue(DfgScope* scope, AstExprIndexExpr* i, DefId incomingDef);
-    DefId visitLValue(DfgScope* scope, AstExprError* e, DefId incomingDef);
+    void visitLValue(AstExpr* e, DefId incomingDef);
+    DefId visitLValue(AstExprLocal* l, DefId incomingDef);
+    DefId visitLValue(AstExprGlobal* g, DefId incomingDef);
+    DefId visitLValue(AstExprIndexName* i, DefId incomingDef);
+    DefId visitLValue(AstExprIndexExpr* i, DefId incomingDef);
+    DefId visitLValue(AstExprError* e, DefId incomingDef);
 
-    void visitType(DfgScope* scope, AstType* t);
-    void visitType(DfgScope* scope, AstTypeReference* r);
-    void visitType(DfgScope* scope, AstTypeTable* t);
-    void visitType(DfgScope* scope, AstTypeFunction* f);
-    void visitType(DfgScope* scope, AstTypeTypeof* t);
-    void visitType(DfgScope* scope, AstTypeUnion* u);
-    void visitType(DfgScope* scope, AstTypeIntersection* i);
-    void visitType(DfgScope* scope, AstTypeError* error);
+    void visitType(AstType* t);
+    void visitType(AstTypeReference* r);
+    void visitType(AstTypeTable* t);
+    void visitType(AstTypeFunction* f);
+    void visitType(AstTypeTypeof* t);
+    void visitType(AstTypeUnion* u);
+    void visitType(AstTypeIntersection* i);
+    void visitType(AstTypeError* error);
 
-    void visitTypePack(DfgScope* scope, AstTypePack* p);
-    void visitTypePack(DfgScope* scope, AstTypePackExplicit* e);
-    void visitTypePack(DfgScope* scope, AstTypePackVariadic* v);
-    void visitTypePack(DfgScope* scope, AstTypePackGeneric* g);
+    void visitTypePack(AstTypePack* p);
+    void visitTypePack(AstTypePackExplicit* e);
+    void visitTypePack(AstTypePackVariadic* v);
+    void visitTypePack(AstTypePackGeneric* g);
 
-    void visitTypeList(DfgScope* scope, AstTypeList l);
+    void visitTypeList(AstTypeList l);
 
-    void visitGenerics(DfgScope* scope, AstArray<AstGenericType> g);
-    void visitGenericPacks(DfgScope* scope, AstArray<AstGenericTypePack> g);
+    void visitGenerics(AstArray<AstGenericType> g);
+    void visitGenericPacks(AstArray<AstGenericTypePack> g);
 };
 
 } // namespace Luau

Analysis/include/Luau/FileResolver.h

@@ -3,6 +3,7 @@
 
 #include <string>
 #include <optional>
+#include <vector>
 
 namespace Luau
 {
@@ -31,6 +32,9 @@ struct ModuleInfo
     bool optional = false;
 };
 
+using RequireSuggestion = std::string;
+using RequireSuggestions = std::vector<RequireSuggestion>;
+
 struct FileResolver
 {
     virtual ~FileResolver() {}
@@ -51,6 +55,11 @@ struct FileResolver
     {
         return std::nullopt;
     }
+
+    virtual std::optional<RequireSuggestions> getRequireSuggestions(const ModuleName& requirer, const std::optional<std::string>& pathString) const
+    {
+        return std::nullopt;
+    }
 };
 
 struct NullFileResolver : FileResolver

Analysis/include/Luau/FragmentAutocomplete.h

@@ -1,12 +1,15 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
-#include "Luau/DenseHash.h"
 #include "Luau/Ast.h"
+#include "Luau/Parser.h"
+#include "Luau/Autocomplete.h"
+#include "Luau/DenseHash.h"
+#include "Luau/Module.h"
 
+#include <memory>
 #include <vector>
 
-
 namespace Luau
 {
 
@@ -15,9 +18,28 @@ struct FragmentAutocompleteAncestryResult
     DenseHashMap<AstName, AstLocal*> localMap{AstName()};
     std::vector<AstLocal*> localStack;
     std::vector<AstNode*> ancestry;
-    AstStat* nearestStatement;
+    AstStat* nearestStatement = nullptr;
+};
+
+struct FragmentParseResult
+{
+    std::string fragmentToParse;
+    AstStatBlock* root = nullptr;
+    std::vector<AstNode*> ancestry;
+    std::unique_ptr<Allocator> alloc = std::make_unique<Allocator>();
 };
 
 FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* root, const Position& cursorPos);
 
+FragmentParseResult parseFragment(const SourceModule& srcModule, std::string_view src, const Position& cursorPos);
+
+AutocompleteResult fragmentAutocomplete(
+    Frontend& frontend,
+    std::string_view src,
+    const ModuleName& moduleName,
+    Position& cursorPosition,
+    StringCompletionCallback callback
+);
+
+
 } // namespace Luau

Analysis/include/Luau/Module.h

@@ -9,6 +9,7 @@
 #include "Luau/Scope.h"
 #include "Luau/TypeArena.h"
 #include "Luau/AnyTypeSummary.h"
+#include "Luau/DataFlowGraph.h"
 
 #include <memory>
 #include <vector>
@@ -131,6 +132,9 @@ struct Module
 
     TypePackId returnType = nullptr;
     std::unordered_map<Name, TypeFun> exportedTypeBindings;
+    // We also need to keep DFG data alive between runs
+    std::shared_ptr<DataFlowGraph> dataFlowGraph = nullptr;
+    std::vector<std::unique_ptr<DfgScope>> dfgScopes;
 
     bool hasModuleScope() const;
     ScopePtr getModuleScope() const;

Analysis/include/Luau/Type.h

@@ -667,6 +667,11 @@ struct AnyType
 {
 };
 
+// A special, trivial type for the refinement system that is always eliminated from intersections.
+struct NoRefineType
+{
+};
+
 // `T | U`
 struct UnionType
 {
@@ -755,6 +760,7 @@ using TypeVariant = Unifiable::Variant<
     UnknownType,
     NeverType,
     NegationType,
+    NoRefineType,
     TypeFunctionInstanceType>;
 
 struct Type final
@@ -949,6 +955,7 @@ public:
     const TypeId unknownType;
     const TypeId neverType;
     const TypeId errorType;
+    const TypeId noRefineType;
     const TypeId falsyType;
     const TypeId truthyType;
 

Analysis/include/Luau/TypeUtils.h

@@ -248,4 +248,36 @@ std::optional<Ty> follow(std::optional<Ty> ty)
         return std::nullopt;
 }
 
+/**
+ * Returns whether or not expr is a literal expression, for example:
+ * - Scalar literals (numbers, booleans, strings, nil)
+ * - Table literals
+ * - Lambdas (a "function literal")
+ */
+bool isLiteral(const AstExpr* expr);
+
+/**
+ * Given a table literal and a mapping from expression to type, determine
+ * whether any literal expression in this table depends on any blocked types.
+ * This is used as a precondition for bidirectional inference: be warned that
+ * the behavior of this algorithm is tightly coupled to that of bidirectional
+ * inference.
+ * @param expr Expression to search
+ * @param astTypes Mapping from AST node to TypeID
+ * @returns A vector of blocked types
+ */
+std::vector<TypeId> findBlockedTypesIn(AstExprTable* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes);
+
+/**
+ * Given a function call and a mapping from expression to type, determine 
+ * whether the type of any argument in said call in depends on a blocked types. 
+ * This is used as a precondition for bidirectional inference: be warned that
+ * the behavior of this algorithm is tightly coupled to that of bidirectional
+ * inference.
+ * @param expr Expression to search
+ * @param astTypes Mapping from AST node to TypeID
+ * @returns A vector of blocked types
+ */
+std::vector<TypeId> findBlockedArgTypesIn(AstExprCall* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes);
+
 } // namespace Luau

Analysis/include/Luau/VisitType.h

@@ -133,6 +133,10 @@ struct GenericTypeVisitor
     {
         return visit(ty);
     }
+    virtual bool visit(TypeId ty, const NoRefineType& nrt)
+    {
+        return visit(ty);
+    }
     virtual bool visit(TypeId ty, const UnknownType& utv)
     {
         return visit(ty);
@@ -345,6 +349,8 @@ struct GenericTypeVisitor
         }
         else if (auto atv = get<AnyType>(ty))
             visit(ty, *atv);
+        else if (auto nrt = get<NoRefineType>(ty))
+            visit(ty, *nrt);
         else if (auto utv = get<UnionType>(ty))
         {
             if (visit(ty, *utv))

Analysis/src/Autocomplete.cpp

@@ -3,6 +3,8 @@
 
 #include "Luau/AstQuery.h"
 #include "Luau/BuiltinDefinitions.h"
+#include "Luau/Common.h"
+#include "Luau/FileResolver.h"
 #include "Luau/Frontend.h"
 #include "Luau/ToString.h"
 #include "Luau/Subtyping.h"
@@ -15,6 +17,7 @@
 
 LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAG(LuauAutocompleteNewSolverLimit)
+LUAU_FASTFLAGVARIABLE(AutocompleteRequirePathSuggestions, false)
 
 LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
 LUAU_FASTINT(LuauTypeInferIterationLimit)
@@ -215,7 +218,6 @@ static TypeCorrectKind checkTypeCorrectKind(
     {
         for (TypeId id : itv->parts)
         {
-            if (DFInt::LuauTypeSolverRelease >= 644)
             id = follow(id);
 
             if (const FunctionType* ftv = get<FunctionType>(id); ftv && checkFunctionType(ftv))
@@ -1444,11 +1446,25 @@ static std::optional<std::string> getStringContents(const AstNode* node)
     }
 }
 
+static std::optional<AutocompleteEntryMap> convertRequireSuggestionsToAutocompleteEntryMap(std::optional<RequireSuggestions> suggestions)
+{
+    if (!suggestions)
+        return std::nullopt;
+
+    AutocompleteEntryMap result;
+    for (const RequireSuggestion& suggestion : *suggestions)
+    {
+        result[suggestion] = {AutocompleteEntryKind::RequirePath};
+    }
+    return result;
+}
+
 static std::optional<AutocompleteEntryMap> autocompleteStringParams(
     const SourceModule& sourceModule,
     const ModulePtr& module,
     const std::vector<AstNode*>& nodes,
     Position position,
+    FileResolver* fileResolver,
     StringCompletionCallback callback
 )
 {
@@ -1495,6 +1511,13 @@ static std::optional<AutocompleteEntryMap> autocompleteStringParams(
     {
         for (const std::string& tag : funcType->tags)
         {
+            if (FFlag::AutocompleteRequirePathSuggestions)
+            {
+                if (tag == kRequireTagName && fileResolver)
+                {
+                    return convertRequireSuggestionsToAutocompleteEntryMap(fileResolver->getRequireSuggestions(module->name, candidateString));
+                }
+            }
             if (std::optional<AutocompleteEntryMap> ret = callback(tag, getMethodContainingClass(module, candidate->func), candidateString))
             {
                 return ret;
@@ -1679,6 +1702,7 @@ static AutocompleteResult autocomplete(
     TypeArena* typeArena,
     Scope* globalScope,
     Position position,
+    FileResolver* fileResolver,
     StringCompletionCallback callback
 )
 {
@@ -1922,7 +1946,7 @@ static AutocompleteResult autocomplete(
     else if (isIdentifier(node) && (parent->is<AstStatExpr>() || parent->is<AstStatError>()))
         return {autocompleteStatement(sourceModule, *module, ancestry, position), ancestry, AutocompleteContext::Statement};
 
-    if (std::optional<AutocompleteEntryMap> ret = autocompleteStringParams(sourceModule, module, ancestry, position, callback))
+    if (std::optional<AutocompleteEntryMap> ret = autocompleteStringParams(sourceModule, module, ancestry, position, fileResolver, callback))
     {
         return {*ret, ancestry, AutocompleteContext::String};
     }
@@ -1999,7 +2023,7 @@ AutocompleteResult autocomplete(Frontend& frontend, const ModuleName& moduleName
         globalScope = frontend.globalsForAutocomplete.globalScope.get();
 
     TypeArena typeArena;
-    return autocomplete(*sourceModule, module, builtinTypes, &typeArena, globalScope, position, callback);
+    return autocomplete(*sourceModule, module, builtinTypes, &typeArena, globalScope, position, frontend.fileResolver, callback);
 }
 
 } // namespace Luau

Analysis/src/BuiltinDefinitions.cpp

@@ -27,6 +27,8 @@
 
 LUAU_FASTFLAG(LuauSolverV2);
 
+LUAU_FASTFLAG(AutocompleteRequirePathSuggestions);
+
 namespace Luau
 {
 
@@ -413,8 +415,18 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
         attachDcrMagicFunction(ttv->props["pack"].type(), dcrMagicFunctionPack);
     }
 
+    if (FFlag::AutocompleteRequirePathSuggestions)
+    {
+        TypeId requireTy = getGlobalBinding(globals, "require");
+        attachTag(requireTy, kRequireTagName);
+        attachMagicFunction(requireTy, magicFunctionRequire);
+        attachDcrMagicFunction(requireTy, dcrMagicFunctionRequire);
+    }
+    else
+    {
         attachMagicFunction(getGlobalBinding(globals, "require"), magicFunctionRequire);
         attachDcrMagicFunction(getGlobalBinding(globals, "require"), dcrMagicFunctionRequire);
+    }
 }
 
 static std::vector<TypeId> parseFormatString(NotNull<BuiltinTypes> builtinTypes, const char* data, size_t size)

Analysis/src/Clone.cpp

@@ -359,6 +359,11 @@ private:
         // noop.
     }
 
+    void cloneChildren(NoRefineType* t)
+    {
+        // noop.
+    }
+
     void cloneChildren(UnionType* t)
     {
         for (TypeId& ty : t->options)

Analysis/src/ConstraintGenerator.cpp

@@ -26,10 +26,10 @@
 #include <algorithm>
 #include <memory>
 
-LUAU_FASTINT(LuauCheckRecursionLimit);
-LUAU_FASTFLAG(DebugLuauLogSolverToJson);
-LUAU_FASTFLAG(DebugLuauMagicTypes);
-LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease);
+LUAU_FASTINT(LuauCheckRecursionLimit)
+LUAU_FASTFLAG(DebugLuauLogSolverToJson)
+LUAU_FASTFLAG(DebugLuauMagicTypes)
+LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
 
 namespace Luau
 {
@@ -2883,9 +2883,45 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprTable* expr,
     {
         Unifier2 unifier{arena, builtinTypes, NotNull{scope.get()}, ice};
         std::vector<TypeId> toBlock;
+        if (DFInt::LuauTypeSolverRelease >= 648)
+        {
+            // This logic is incomplete as we want to re-run this 
+            // _after_ blocked types have resolved, but this
+            // allows us to do some bidirectional inference.
+            toBlock = findBlockedTypesIn(expr, NotNull{&module->astTypes});
+            if (toBlock.empty())
+            {
                 matchLiteralType(
-            NotNull{&module->astTypes}, NotNull{&module->astExpectedTypes}, builtinTypes, arena, NotNull{&unifier}, *expectedType, ty, expr, toBlock
+                    NotNull{&module->astTypes},
+                    NotNull{&module->astExpectedTypes},
+                    builtinTypes,
+                    arena,
+                    NotNull{&unifier},
+                    *expectedType,
+                    ty,
+                    expr,
+                    toBlock
                 );
+                // The visitor we ran prior should ensure that there are no
+                // blocked types that we would encounter while matching on 
+                // this expression.
+                LUAU_ASSERT(toBlock.empty());
+            }
+        }
+        else
+        {
+            matchLiteralType(
+                NotNull{&module->astTypes},
+                NotNull{&module->astExpectedTypes},
+                builtinTypes,
+                arena,
+                NotNull{&unifier},
+                *expectedType,
+                ty,
+                expr,
+                toBlock
+            );
+        }
     }
 
     return Inference{ty};

Analysis/src/ConstraintSolver.cpp

@@ -32,6 +32,7 @@ LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverIncludeDependencies, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogBindings, false)
 LUAU_FASTINTVARIABLE(LuauSolverRecursionLimit, 500)
 LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
+LUAU_FASTFLAGVARIABLE(LuauRemoveNotAnyHack, false)
 
 namespace Luau
 {
@@ -1238,6 +1239,13 @@ bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<cons
             continue;
         }
 
+        if (FFlag::LuauRemoveNotAnyHack)
+        {
+            // We bind any unused discriminants to the `*no-refine*` type indicating that it can be safely ignored.
+            emplaceType<BoundType>(asMutable(follow(*ty)), builtinTypes->noRefineType);
+        }
+        else
+        {
             // We use `any` here because the discriminant type may be pointed at by both branches,
             // where the discriminant type is not negated, and the other where it is negated, i.e.
             // `unknown ~ unknown` and `~unknown ~ never`, so `T & unknown ~ T` and `T & ~unknown ~ never`
@@ -1247,6 +1255,7 @@ bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<cons
             // In practice, users cannot negate `any`, so this is an implementation detail we can always change.
             emplaceType<BoundType>(asMutable(follow(*ty)), builtinTypes->anyType);
         }
+    }
 
     OverloadResolver resolver{
         builtinTypes,
@@ -1322,6 +1331,22 @@ bool ConstraintSolver::tryDispatch(const FunctionCheckConstraint& c, NotNull<con
     if (isBlocked(argsPack))
         return true;
 
+    if (DFInt::LuauTypeSolverRelease >= 648)
+    {
+        // This is expensive as we need to traverse a (potentially large)
+        // literal up front in order to determine if there are any blocked
+        // types, otherwise we may run `matchTypeLiteral` multiple times, 
+        // which right now may fail due to being non-idempotent (it
+        // destructively updates the underlying literal type).
+        auto blockedTypes = findBlockedArgTypesIn(c.callSite, c.astTypes);
+        for (const auto ty : blockedTypes)
+        {
+            block(ty, constraint);
+        }
+        if (!blockedTypes.empty())
+            return false;
+    }
+
     // We know the type of the function and the arguments it expects to receive.
     // We also know the TypeIds of the actual arguments that will be passed.
     //
@@ -1384,7 +1409,7 @@ bool ConstraintSolver::tryDispatch(const FunctionCheckConstraint& c, NotNull<con
     {
         const TypeId expectedArgTy = follow(expectedArgs[i + typeOffset]);
         const TypeId actualArgTy = follow(argPackHead[i + typeOffset]);
-        const AstExpr* expr = unwrapGroup(c.callSite->args.data[i]);
+        AstExpr* expr = unwrapGroup(c.callSite->args.data[i]);
 
         (*c.astExpectedTypes)[expr] = expectedArgTy;
 
@@ -1416,12 +1441,19 @@ bool ConstraintSolver::tryDispatch(const FunctionCheckConstraint& c, NotNull<con
             Unifier2 u2{arena, builtinTypes, constraint->scope, NotNull{&iceReporter}};
             std::vector<TypeId> toBlock;
             (void)matchLiteralType(c.astTypes, c.astExpectedTypes, builtinTypes, arena, NotNull{&u2}, expectedArgTy, actualArgTy, expr, toBlock);
+            if (DFInt::LuauTypeSolverRelease >= 648)
+            {
+                LUAU_ASSERT(toBlock.empty());
+            }
+            else
+            {
                 for (auto t : toBlock)
                     block(t, constraint);
                 if (!toBlock.empty())
                     return false;
             }
         }
+    }
 
     return true;
 }
@@ -1748,8 +1780,9 @@ bool ConstraintSolver::tryDispatch(const AssignPropConstraint& c, NotNull<const
 
     if (auto lhsFree = getMutable<FreeType>(lhsType))
     {
-        if (get<TableType>(lhsFree->upperBound) || get<MetatableType>(lhsFree->upperBound))
-            lhsType = lhsFree->upperBound;
+        auto lhsFreeUpperBound = DFInt::LuauTypeSolverRelease >= 648 ? follow(lhsFree->upperBound) : lhsFree->upperBound;
+        if (get<TableType>(lhsFreeUpperBound) || get<MetatableType>(lhsFreeUpperBound))
+            lhsType = lhsFreeUpperBound;
         else
         {
             TypeId newUpperBound = arena->addType(TableType{TableState::Free, TypeLevel{}, constraint->scope});
@@ -1759,7 +1792,7 @@ bool ConstraintSolver::tryDispatch(const AssignPropConstraint& c, NotNull<const
             upperTable->props[c.propName] = rhsType;
 
             // Food for thought: Could we block if simplification encounters a blocked type?
-            lhsFree->upperBound = simplifyIntersection(builtinTypes, arena, lhsFree->upperBound, newUpperBound).result;
+            lhsFree->upperBound = simplifyIntersection(builtinTypes, arena, lhsFreeUpperBound, newUpperBound).result;
 
             bind(constraint, c.propType, rhsType);
             return true;

Analysis/src/Differ.cpp

@@ -13,6 +13,7 @@
 
 namespace Luau
 {
+
 std::string DiffPathNode::toString() const
 {
     switch (kind)
@@ -944,12 +945,14 @@ std::vector<std::pair<TypeId, TypeId>>::const_reverse_iterator DifferEnvironment
     return visitingStack.crend();
 }
 
+
 DifferResult diff(TypeId ty1, TypeId ty2)
 {
     DifferEnvironment differEnv{ty1, ty2, std::nullopt, std::nullopt};
     return diffUsingEnv(differEnv, ty1, ty2);
 }
 
+
 DifferResult diffWithSymbols(TypeId ty1, TypeId ty2, std::optional<std::string> symbol1, std::optional<std::string> symbol2)
 {
     DifferEnvironment differEnv{ty1, ty2, symbol1, symbol2};

Analysis/src/EmbeddedBuiltinDefinitions.cpp

@@ -1,10 +1,13 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
 
+LUAU_FASTFLAG(LuauMathMap)
+
 namespace Luau
 {
 
-static const std::string kBuiltinDefinitionLuaSrcChecked = R"BUILTIN_SRC(
+// TODO: there has to be a better way, like splitting up per library
+static const std::string kBuiltinDefinitionLuaSrcChecked_DEPRECATED = R"BUILTIN_SRC(
 
 declare bit32: {
     band: @checked (...number) -> number,
@@ -195,6 +198,228 @@ declare utf8: {
 declare function unpack<V>(tab: {V}, i: number?, j: number?): ...V
 
 
+--- Buffer API
+declare buffer: {
+    create: @checked (size: number) -> buffer,
+    fromstring: @checked (str: string) -> buffer,
+    tostring: @checked (b: buffer) -> string,
+    len: @checked (b: buffer) -> number,
+    copy: @checked (target: buffer, targetOffset: number, source: buffer, sourceOffset: number?, count: number?) -> (),
+    fill: @checked (b: buffer, offset: number, value: number, count: number?) -> (),
+    readi8: @checked (b: buffer, offset: number) -> number,
+    readu8: @checked (b: buffer, offset: number) -> number,
+    readi16: @checked (b: buffer, offset: number) -> number,
+    readu16: @checked (b: buffer, offset: number) -> number,
+    readi32: @checked (b: buffer, offset: number) -> number,
+    readu32: @checked (b: buffer, offset: number) -> number,
+    readf32: @checked (b: buffer, offset: number) -> number,
+    readf64: @checked (b: buffer, offset: number) -> number,
+    writei8: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu8: @checked (b: buffer, offset: number, value: number) -> (),
+    writei16: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu16: @checked (b: buffer, offset: number, value: number) -> (),
+    writei32: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu32: @checked (b: buffer, offset: number, value: number) -> (),
+    writef32: @checked (b: buffer, offset: number, value: number) -> (),
+    writef64: @checked (b: buffer, offset: number, value: number) -> (),
+    readstring: @checked (b: buffer, offset: number, count: number) -> string,
+    writestring: @checked (b: buffer, offset: number, value: string, count: number?) -> (),
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionLuaSrcChecked = R"BUILTIN_SRC(
+
+declare bit32: {
+    band: @checked (...number) -> number,
+    bor: @checked (...number) -> number,
+    bxor: @checked (...number) -> number,
+    btest: @checked (number, ...number) -> boolean,
+    rrotate: @checked (x: number, disp: number) -> number,
+    lrotate: @checked (x: number, disp: number) -> number,
+    lshift: @checked (x: number, disp: number) -> number,
+    arshift: @checked (x: number, disp: number) -> number,
+    rshift: @checked (x: number, disp: number) -> number,
+    bnot: @checked (x: number) -> number,
+    extract: @checked (n: number, field: number, width: number?) -> number,
+    replace: @checked (n: number, v: number, field: number, width: number?) -> number,
+    countlz: @checked (n: number) -> number,
+    countrz: @checked (n: number) -> number,
+    byteswap: @checked (n: number) -> number,
+}
+
+declare math: {
+    frexp: @checked (n: number) -> (number, number),
+    ldexp: @checked (s: number, e: number) -> number,
+    fmod: @checked (x: number, y: number) -> number,
+    modf: @checked (n: number) -> (number, number),
+    pow: @checked (x: number, y: number) -> number,
+    exp: @checked (n: number) -> number,
+
+    ceil: @checked (n: number) -> number,
+    floor: @checked (n: number) -> number,
+    abs: @checked (n: number) -> number,
+    sqrt: @checked (n: number) -> number,
+
+    log: @checked (n: number, base: number?) -> number,
+    log10: @checked (n: number) -> number,
+
+    rad: @checked (n: number) -> number,
+    deg: @checked (n: number) -> number,
+
+    sin: @checked (n: number) -> number,
+    cos: @checked (n: number) -> number,
+    tan: @checked (n: number) -> number,
+    sinh: @checked (n: number) -> number,
+    cosh: @checked (n: number) -> number,
+    tanh: @checked (n: number) -> number,
+    atan: @checked (n: number) -> number,
+    acos: @checked (n: number) -> number,
+    asin: @checked (n: number) -> number,
+    atan2: @checked (y: number, x: number) -> number,
+
+    min: @checked (number, ...number) -> number,
+    max: @checked (number, ...number) -> number,
+
+    pi: number,
+    huge: number,
+
+    randomseed: @checked (seed: number) -> (),
+    random: @checked (number?, number?) -> number,
+
+    sign: @checked (n: number) -> number,
+    clamp: @checked (n: number, min: number, max: number) -> number,
+    noise: @checked (x: number, y: number?, z: number?) -> number,
+    round: @checked (n: number) -> number,
+    map: @checked (x: number, inmin: number, inmax: number, outmin: number, outmax: number) -> number,
+}
+
+type DateTypeArg = {
+    year: number,
+    month: number,
+    day: number,
+    hour: number?,
+    min: number?,
+    sec: number?,
+    isdst: boolean?,
+}
+
+type DateTypeResult = {
+    year: number,
+    month: number,
+    wday: number,
+    yday: number,
+    day: number,
+    hour: number,
+    min: number,
+    sec: number,
+    isdst: boolean,
+}
+
+declare os: {
+    time: (time: DateTypeArg?) -> number,
+    date: ((formatString: "*t" | "!*t", time: number?) -> DateTypeResult) & ((formatString: string?, time: number?) -> string),
+    difftime: (t2: DateTypeResult | number, t1: DateTypeResult | number) -> number,
+    clock: () -> number,
+}
+
+@checked declare function require(target: any): any
+
+@checked declare function getfenv(target: any): { [string]: any }
+
+declare _G: any
+declare _VERSION: string
+
+declare function gcinfo(): number
+
+declare function print<T...>(...: T...)
+
+declare function type<T>(value: T): string
+declare function typeof<T>(value: T): string
+
+-- `assert` has a magic function attached that will give more detailed type information
+declare function assert<T>(value: T, errorMessage: string?): T
+declare function error<T>(message: T, level: number?): never
+
+declare function tostring<T>(value: T): string
+declare function tonumber<T>(value: T, radix: number?): number?
+
+declare function rawequal<T1, T2>(a: T1, b: T2): boolean
+declare function rawget<K, V>(tab: {[K]: V}, k: K): V
+declare function rawset<K, V>(tab: {[K]: V}, k: K, v: V): {[K]: V}
+declare function rawlen<K, V>(obj: {[K]: V} | string): number
+
+declare function setfenv<T..., R...>(target: number | (T...) -> R..., env: {[string]: any}): ((T...) -> R...)?
+
+declare function ipairs<V>(tab: {V}): (({V}, number) -> (number?, V), {V}, number)
+
+declare function pcall<A..., R...>(f: (A...) -> R..., ...: A...): (boolean, R...)
+
+-- FIXME: The actual type of `xpcall` is:
+-- <E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., A...) -> (true, R1...) | (false, R2...)
+-- Since we can't represent the return value, we use (boolean, R1...).
+declare function xpcall<E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., ...: A...): (boolean, R1...)
+
+-- `select` has a magic function attached to provide more detailed type information
+declare function select<A...>(i: string | number, ...: A...): ...any
+
+-- FIXME: This type is not entirely correct - `loadstring` returns a function or
+-- (nil, string).
+declare function loadstring<A...>(src: string, chunkname: string?): (((A...) -> any)?, string?)
+
+@checked declare function newproxy(mt: boolean?): any
+
+declare coroutine: {
+    create: <A..., R...>(f: (A...) -> R...) -> thread,
+    resume: <A..., R...>(co: thread, A...) -> (boolean, R...),
+    running: () -> thread,
+    status: @checked (co: thread) -> "dead" | "running" | "normal" | "suspended",
+    wrap: <A..., R...>(f: (A...) -> R...) -> ((A...) -> R...),
+    yield: <A..., R...>(A...) -> R...,
+    isyieldable: () -> boolean,
+    close: @checked (co: thread) -> (boolean, any)
+}
+
+declare table: {
+    concat: <V>(t: {V}, sep: string?, i: number?, j: number?) -> string,
+    insert: (<V>(t: {V}, value: V) -> ()) & (<V>(t: {V}, pos: number, value: V) -> ()),
+    maxn: <V>(t: {V}) -> number,
+    remove: <V>(t: {V}, number?) -> V?,
+    sort: <V>(t: {V}, comp: ((V, V) -> boolean)?) -> (),
+    create: <V>(count: number, value: V?) -> {V},
+    find: <V>(haystack: {V}, needle: V, init: number?) -> number?,
+
+    unpack: <V>(list: {V}, i: number?, j: number?) -> ...V,
+    pack: <V>(...V) -> { n: number, [number]: V },
+
+    getn: <V>(t: {V}) -> number,
+    foreach: <K, V>(t: {[K]: V}, f: (K, V) -> ()) -> (),
+    foreachi: <V>({V}, (number, V) -> ()) -> (),
+
+    move: <V>(src: {V}, a: number, b: number, t: number, dst: {V}?) -> {V},
+    clear: <K, V>(table: {[K]: V}) -> (),
+
+    isfrozen: <K, V>(t: {[K]: V}) -> boolean,
+}
+
+declare debug: {
+    info: (<R...>(thread: thread, level: number, options: string) -> R...) & (<R...>(level: number, options: string) -> R...) & (<A..., R1..., R2...>(func: (A...) -> R1..., options: string) -> R2...),
+    traceback: ((message: string?, level: number?) -> string) & ((thread: thread, message: string?, level: number?) -> string),
+}
+
+declare utf8: {
+    char: @checked (...number) -> string,
+    charpattern: string,
+    codes: @checked (str: string) -> ((string, number) -> (number, number), string, number),
+    codepoint: @checked (str: string, i: number?, j: number?) -> ...number,
+    len: @checked (s: string, i: number?, j: number?) -> (number?, number?),
+    offset: @checked (s: string, n: number?, i: number?) -> number,
+}
+
+-- Cannot use `typeof` here because it will produce a polytype when we expect a monotype.
+declare function unpack<V>(tab: {V}, i: number?, j: number?): ...V
+
+
 --- Buffer API
 declare buffer: {
     create: @checked (size: number) -> buffer,
@@ -227,7 +452,7 @@ declare buffer: {
 
 std::string getBuiltinDefinitionSource()
 {
-    std::string result = kBuiltinDefinitionLuaSrcChecked;
+    std::string result = FFlag::LuauMathMap ? kBuiltinDefinitionLuaSrcChecked : kBuiltinDefinitionLuaSrcChecked_DEPRECATED;
     return result;
 }
 

Analysis/src/FragmentAutocomplete.cpp

@@ -3,6 +3,11 @@
 
 #include "Luau/Ast.h"
 #include "Luau/AstQuery.h"
+#include "Luau/Common.h"
+#include "Luau/Frontend.h"
+#include "Luau/Parser.h"
+#include "Luau/ParseOptions.h"
+#include "Luau/Module.h"
 
 namespace Luau
 {
@@ -10,6 +15,8 @@ namespace Luau
 FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* root, const Position& cursorPos)
 {
     std::vector<AstNode*> ancestry = findAncestryAtPositionForAutocomplete(root, cursorPos);
+    // Should always contain the root AstStat
+    LUAU_ASSERT(ancestry.size() >= 1);
     DenseHashMap<AstName, AstLocal*> localMap{AstName()};
     std::vector<AstLocal*> localStack;
     AstStat* nearestStatement = nullptr;
@@ -21,7 +28,7 @@ FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* ro
             {
                 if (stat->location.begin <= cursorPos)
                     nearestStatement = stat;
-                if (stat->location.begin <= cursorPos)
+                if (stat->location.begin < cursorPos && stat->location.begin.line < cursorPos.line)
                 {
                     // This statement precedes the current one
                     if (auto loc = stat->as<AstStatLocal>())
@@ -42,7 +49,116 @@ FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* ro
         }
     }
 
+    if (!nearestStatement)
+        nearestStatement = ancestry[0]->asStat();
+    LUAU_ASSERT(nearestStatement);
     return {std::move(localMap), std::move(localStack), std::move(ancestry), std::move(nearestStatement)};
 }
 
+std::pair<unsigned int, unsigned int> getDocumentOffsets(const std::string_view& src, const Position& startPos, const Position& endPos)
+{
+    unsigned int lineCount = 0;
+    unsigned int colCount = 0;
+
+    unsigned int docOffset = 0;
+    unsigned int startOffset = 0;
+    unsigned int endOffset = 0;
+    bool foundStart = false;
+    bool foundEnd = false;
+    for (char c : src)
+    {
+        if (foundStart && foundEnd)
+            break;
+
+        if (startPos.line == lineCount && startPos.column == colCount)
+        {
+            foundStart = true;
+            startOffset = docOffset;
+        }
+
+        if (endPos.line == lineCount && endPos.column == colCount)
+        {
+            endOffset = docOffset;
+            foundEnd = true;
+        }
+
+        if (c == '\n')
+        {
+            lineCount++;
+            colCount = 0;
+        }
+        else
+            colCount++;
+        docOffset++;
+    }
+
+
+    unsigned int min = std::min(startOffset, endOffset);
+    unsigned int len = std::max(startOffset, endOffset) - min;
+    return {min, len};
+}
+
+ScopePtr findClosestScope(const ModulePtr& module, const Position& cursorPos)
+{
+    LUAU_ASSERT(module->hasModuleScope());
+
+    ScopePtr closest = module->getModuleScope();
+    for (auto [loc, sc] : module->scopes)
+    {
+        if (loc.begin <= cursorPos && closest->location.begin <= loc.begin)
+            closest = sc;
+    }
+
+    return closest;
+}
+
+FragmentParseResult parseFragment(const SourceModule& srcModule, std::string_view src, const Position& cursorPos)
+{
+    FragmentAutocompleteAncestryResult result = findAncestryForFragmentParse(srcModule.root, cursorPos);
+    ParseOptions opts;
+    opts.allowDeclarationSyntax = false;
+    opts.captureComments = false;
+    opts.parseFragment = FragmentParseResumeSettings{std::move(result.localMap), std::move(result.localStack)};
+    AstStat* enclosingStatement = result.nearestStatement;
+
+    const Position& endPos = cursorPos;
+    // If the statement starts on a previous line, grab the statement beginning
+    // otherwise, grab the statement end to whatever is being typed right now
+    const Position& startPos =
+        enclosingStatement->location.begin.line == cursorPos.line ? enclosingStatement->location.begin : enclosingStatement->location.end;
+
+    auto [offsetStart, parseLength] = getDocumentOffsets(src, startPos, endPos);
+
+    const char* srcStart = src.data() + offsetStart;
+    std::string_view dbg = src.substr(offsetStart, parseLength);
+    const std::shared_ptr<AstNameTable>& nameTbl = srcModule.names;
+    FragmentParseResult fragmentResult;
+    fragmentResult.fragmentToParse = std::string(dbg.data(), parseLength);
+    // For the duration of the incremental parse, we want to allow the name table to re-use duplicate names
+    ParseResult p = Luau::Parser::parse(srcStart, parseLength, *nameTbl, *fragmentResult.alloc.get(), opts);
+
+    std::vector<AstNode*> fabricatedAncestry = std::move(result.ancestry);
+    std::vector<AstNode*> fragmentAncestry = findAncestryAtPositionForAutocomplete(p.root, p.root->location.end);
+    fabricatedAncestry.insert(fabricatedAncestry.end(), fragmentAncestry.begin(), fragmentAncestry.end());
+    if (enclosingStatement == nullptr)
+        enclosingStatement = p.root;
+    fragmentResult.root = std::move(p.root);
+    fragmentResult.ancestry = std::move(fabricatedAncestry);
+    return fragmentResult;
+}
+
+
+AutocompleteResult fragmentAutocomplete(
+    Frontend& frontend,
+    std::string_view src,
+    const ModuleName& moduleName,
+    Position& cursorPosition,
+    StringCompletionCallback callback
+)
+{
+    LUAU_ASSERT(FFlag::LuauSolverV2);
+    // TODO
+    return {};
+}
+
 } // namespace Luau

Analysis/src/Frontend.cpp

@@ -49,6 +49,7 @@ LUAU_DYNAMIC_FASTFLAGVARIABLE(LuauRunCustomModuleChecks, false)
 LUAU_FASTFLAGVARIABLE(LuauMoreThoroughCycleDetection, false)
 
 LUAU_FASTFLAG(StudioReportLuauAny2)
+LUAU_FASTFLAGVARIABLE(LuauStoreDFGOnModule, false)
 
 namespace Luau
 {
@@ -1315,6 +1316,18 @@ ModulePtr check(
     }
 
     DataFlowGraph dfg = DataFlowGraphBuilder::build(sourceModule.root, iceHandler);
+    DataFlowGraph* dfgForConstraintGeneration = nullptr;
+    if (FFlag::LuauStoreDFGOnModule)
+    {
+        auto [dfg, scopes] = DataFlowGraphBuilder::buildShared(sourceModule.root, iceHandler);
+        result->dataFlowGraph = std::move(dfg);
+        result->dfgScopes = std::move(scopes);
+        dfgForConstraintGeneration = result->dataFlowGraph.get();
+    }
+    else
+    {
+        dfgForConstraintGeneration = &dfg;
+    }
 
     UnifierSharedState unifierState{iceHandler};
     unifierState.counters.recursionLimit = FInt::LuauTypeInferRecursionLimit;
@@ -1336,7 +1349,7 @@ ModulePtr check(
         parentScope,
         std::move(prepareModuleScope),
         logger.get(),
-        NotNull{&dfg},
+        NotNull{dfgForConstraintGeneration},
         requireCycles
     };
 

Analysis/src/Generalization.cpp

@@ -801,6 +801,12 @@ struct TypeCacher : TypeOnceVisitor
         return false;
     }
 
+    bool visit(TypeId ty, const NoRefineType&) override
+    {
+        cache(ty);
+        return false;
+    }
+
     bool visit(TypeId ty, const UnionType& ut) override
     {
         if (isUncacheable(ty) || isCached(ty))

Analysis/src/NonStrictTypeChecker.cpp

@@ -594,7 +594,7 @@ struct NonStrictTypeChecker
                     std::shared_ptr<const NormalizedType> norm = normalizer.normalize(expectedArgType);
                     DefId def = dfg->getDef(arg);
                     TypeId runTimeErrorTy;
-                    // If we're dealing with any, negating any will cause all subtype tests to fail, since ~any is any
+                    // If we're dealing with any, negating any will cause all subtype tests to fail
                     // However, when someone calls this function, they're going to want to be able to pass it anything,
                     // for that reason, we manually inject never into the context so that the runtime test will always pass.
                     if (!norm)

Analysis/src/Normalize.cpp

@@ -1872,7 +1872,7 @@ NormalizationResult Normalizer::unionNormalWithTy(NormalizedType& here, TypeId t
         if (res != NormalizationResult::True)
             return res;
     }
-    else if (get<PendingExpansionType>(there) || get<TypeFunctionInstanceType>(there))
+    else if (get<PendingExpansionType>(there) || get<TypeFunctionInstanceType>(there) || get<NoRefineType>(there))
     {
         // nothing
     }
@@ -3217,6 +3217,11 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
             // assumption that it is the same as any.
             return NormalizationResult::True;
         }
+        else if (get<NoRefineType>(t))
+        {
+            // `*no-refine*` means we will never do anything to affect the intersection.
+            return NormalizationResult::True;
+        }
         else if (get<NeverType>(t))
         {
             // if we're intersecting with `~never`, this is equivalent to intersecting with `unknown`
@@ -3243,6 +3248,11 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
     {
         here.classes.resetToNever();
     }
+    else if (get<NoRefineType>(there))
+    {
+        // `*no-refine*` means we will never do anything to affect the intersection.
+        return NormalizationResult::True;
+    }
     else
         LUAU_ASSERT(!"Unreachable");
 

Analysis/src/Substitution.cpp

@@ -50,6 +50,11 @@ static TypeId shallowClone(TypeId ty, TypeArena& dest, const TxnLog* log, bool a
             LUAU_ASSERT(ty->persistent);
             return ty;
         }
+        else if constexpr (std::is_same_v<T, NoRefineType>)
+        {
+            LUAU_ASSERT(ty->persistent);
+            return ty;
+        }
         else if constexpr (std::is_same_v<T, ErrorType>)
         {
             LUAU_ASSERT(ty->persistent);

Analysis/src/Subtyping.cpp

@@ -261,52 +261,30 @@ SubtypingResult SubtypingResult::any(const std::vector<SubtypingResult>& results
 
 struct ApplyMappedGenerics : Substitution
 {
-    using MappedGenerics = DenseHashMap<TypeId, SubtypingEnvironment::GenericBounds>;
-    using MappedGenericPacks = DenseHashMap<TypePackId, TypePackId>;
-
     NotNull<BuiltinTypes> builtinTypes;
     NotNull<TypeArena> arena;
 
     SubtypingEnvironment& env;
 
-    MappedGenerics& mappedGenerics_DEPRECATED;
-    MappedGenericPacks& mappedGenericPacks_DEPRECATED;
-
-    ApplyMappedGenerics(
-        NotNull<BuiltinTypes> builtinTypes,
-        NotNull<TypeArena> arena,
-        SubtypingEnvironment& env,
-        MappedGenerics& mappedGenerics,
-        MappedGenericPacks& mappedGenericPacks
-    )
+    ApplyMappedGenerics(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, SubtypingEnvironment& env)
         : Substitution(TxnLog::empty(), arena)
         , builtinTypes(builtinTypes)
         , arena(arena)
         , env(env)
-        , mappedGenerics_DEPRECATED(mappedGenerics)
-        , mappedGenericPacks_DEPRECATED(mappedGenericPacks)
     {
     }
 
     bool isDirty(TypeId ty) override
     {
-        if (DFInt::LuauTypeSolverRelease >= 644)
         return env.containsMappedType(ty);
-        else
-            return mappedGenerics_DEPRECATED.contains(ty);
     }
 
     bool isDirty(TypePackId tp) override
     {
-        if (DFInt::LuauTypeSolverRelease >= 644)
         return env.containsMappedPack(tp);
-        else
-            return mappedGenericPacks_DEPRECATED.contains(tp);
     }
 
     TypeId clean(TypeId ty) override
-    {
-        if (DFInt::LuauTypeSolverRelease >= 644)
     {
         const auto& bounds = env.getMappedTypeBounds(ty);
 
@@ -318,23 +296,8 @@ struct ApplyMappedGenerics : Substitution
 
         return arena->addType(IntersectionType{std::vector<TypeId>(begin(bounds.upperBound), end(bounds.upperBound))});
     }
-        else
-        {
-            const auto& bounds = mappedGenerics_DEPRECATED[ty];
-
-            if (bounds.upperBound.empty())
-                return builtinTypes->unknownType;
-
-            if (bounds.upperBound.size() == 1)
-                return *begin(bounds.upperBound);
-
-            return arena->addType(IntersectionType{std::vector<TypeId>(begin(bounds.upperBound), end(bounds.upperBound))});
-        }
-    }
 
     TypePackId clean(TypePackId tp) override
-    {
-        if (DFInt::LuauTypeSolverRelease >= 644)
     {
         if (auto it = env.getMappedPackBounds(tp))
             return *it;
@@ -343,11 +306,6 @@ struct ApplyMappedGenerics : Substitution
         LUAU_ASSERT(!"Unreachable");
         return nullptr;
     }
-        else
-        {
-            return mappedGenericPacks_DEPRECATED[tp];
-        }
-    }
 
     bool ignoreChildren(TypeId ty) override
     {
@@ -364,7 +322,7 @@ struct ApplyMappedGenerics : Substitution
 
 std::optional<TypeId> SubtypingEnvironment::applyMappedGenerics(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId ty)
 {
-    ApplyMappedGenerics amg{builtinTypes, arena, *this, mappedGenerics, mappedGenericPacks};
+    ApplyMappedGenerics amg{builtinTypes, arena, *this};
     return amg.substitute(ty);
 }
 
@@ -489,8 +447,6 @@ SubtypingResult Subtyping::isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope
         }
 
 
-        if (DFInt::LuauTypeSolverRelease >= 644)
-        {
         SubtypingEnvironment boundsEnv;
         boundsEnv.parent = &env;
         SubtypingResult boundsResult = isCovariantWith(boundsEnv, lowerBound, upperBound, scope);
@@ -498,14 +454,6 @@ SubtypingResult Subtyping::isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope
 
         result.andAlso(boundsResult);
     }
-        else
-        {
-            SubtypingResult boundsResult = isCovariantWith(env, lowerBound, upperBound, scope);
-            boundsResult.reasoning.clear();
-
-            result.andAlso(boundsResult);
-        }
-    }
 
     /* TODO: We presently don't store subtype test results in the persistent
      * cache if the left-side type is a generic function.
@@ -582,18 +530,17 @@ SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, TypeId sub
     subTy = follow(subTy);
     superTy = follow(superTy);
 
-    if (const TypeId* subIt = (DFInt::LuauTypeSolverRelease >= 644 ? env.tryFindSubstitution(subTy) : env.substitutions.find(subTy)); subIt && *subIt)
+    if (const TypeId* subIt = env.tryFindSubstitution(subTy); subIt && *subIt)
         subTy = *subIt;
 
-    if (const TypeId* superIt = (DFInt::LuauTypeSolverRelease >= 644 ? env.tryFindSubstitution(superTy) : env.substitutions.find(superTy));
-        superIt && *superIt)
+    if (const TypeId* superIt = env.tryFindSubstitution(superTy); superIt && *superIt)
         superTy = *superIt;
 
     const SubtypingResult* cachedResult = resultCache.find({subTy, superTy});
     if (cachedResult)
         return *cachedResult;
 
-    cachedResult = DFInt::LuauTypeSolverRelease >= 644 ? env.tryFindSubtypingResult({subTy, superTy}) : env.ephemeralCache.find({subTy, superTy});
+    cachedResult = env.tryFindSubtypingResult({subTy, superTy});
     if (cachedResult)
         return *cachedResult;
 
@@ -838,8 +785,7 @@ SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, TypePackId
                     std::vector<TypeId> headSlice(begin(superHead), begin(superHead) + headSize);
                     TypePackId superTailPack = arena->addTypePack(std::move(headSlice), superTail);
 
-                    if (TypePackId* other =
-                            (DFInt::LuauTypeSolverRelease >= 644 ? env.getMappedPackBounds(*subTail) : env.mappedGenericPacks.find(*subTail)))
+                    if (TypePackId* other = env.getMappedPackBounds(*subTail))
                         // TODO: TypePath can't express "slice of a pack + its tail".
                         results.push_back(isCovariantWith(env, *other, superTailPack, scope).withSubComponent(TypePath::PackField::Tail));
                     else
@@ -894,8 +840,7 @@ SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, TypePackId
                     std::vector<TypeId> headSlice(begin(subHead), begin(subHead) + headSize);
                     TypePackId subTailPack = arena->addTypePack(std::move(headSlice), subTail);
 
-                    if (TypePackId* other =
-                            (DFInt::LuauTypeSolverRelease >= 644 ? env.getMappedPackBounds(*superTail) : env.mappedGenericPacks.find(*superTail)))
+                    if (TypePackId* other = env.getMappedPackBounds(*superTail))
                         // TODO: TypePath can't express "slice of a pack + its tail".
                         results.push_back(isContravariantWith(env, subTailPack, *other, scope).withSuperComponent(TypePath::PackField::Tail));
                     else
@@ -1837,11 +1782,8 @@ bool Subtyping::bindGeneric(SubtypingEnvironment& env, TypeId subTy, TypeId supe
         if (!get<GenericType>(subTy))
             return false;
 
-        if (DFInt::LuauTypeSolverRelease >= 644)
-        {
         if (!env.mappedGenerics.find(subTy) && env.containsMappedType(subTy))
             iceReporter->ice("attempting to modify bounds of a potentially visited generic");
-        }
 
         env.mappedGenerics[subTy].upperBound.insert(superTy);
     }
@@ -1850,11 +1792,8 @@ bool Subtyping::bindGeneric(SubtypingEnvironment& env, TypeId subTy, TypeId supe
         if (!get<GenericType>(superTy))
             return false;
 
-        if (DFInt::LuauTypeSolverRelease >= 644)
-        {
         if (!env.mappedGenerics.find(superTy) && env.containsMappedType(superTy))
             iceReporter->ice("attempting to modify bounds of a potentially visited generic");
-        }
 
         env.mappedGenerics[superTy].lowerBound.insert(subTy);
     }
@@ -1901,7 +1840,7 @@ bool Subtyping::bindGeneric(SubtypingEnvironment& env, TypePackId subTp, TypePac
     if (!get<GenericTypePack>(subTp))
         return false;
 
-    if (TypePackId* m = (DFInt::LuauTypeSolverRelease >= 644 ? env.getMappedPackBounds(subTp) : env.mappedGenericPacks.find(subTp)))
+    if (TypePackId* m = env.getMappedPackBounds(subTp))
         return *m == superTp;
 
     env.mappedGenericPacks[subTp] = superTp;

Analysis/src/TableLiteralInference.cpp

@@ -6,19 +6,14 @@
 #include "Luau/Type.h"
 #include "Luau/ToString.h"
 #include "Luau/TypeArena.h"
+#include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
 
+LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
+
 namespace Luau
 {
 
-static bool isLiteral(const AstExpr* expr)
-{
-    return (
-        expr->is<AstExprTable>() || expr->is<AstExprFunction>() || expr->is<AstExprConstantNumber>() || expr->is<AstExprConstantString>() ||
-        expr->is<AstExprConstantBool>() || expr->is<AstExprConstantNil>()
-    );
-}
-
 // A fast approximation of subTy <: superTy
 static bool fastIsSubtype(TypeId subTy, TypeId superTy)
 {
@@ -381,15 +376,21 @@ TypeId matchLiteralType(
                 const TypeId* keyTy = astTypes->find(item.key);
                 LUAU_ASSERT(keyTy);
                 TypeId tKey = follow(*keyTy);
-                if (get<BlockedType>(tKey))
+                if (DFInt::LuauTypeSolverRelease >= 648)
+                {
+                    LUAU_ASSERT(!is<BlockedType>(tKey));
+                }
+                else if (get<BlockedType>(tKey))
                     toBlock.push_back(tKey);
-
                 const TypeId* propTy = astTypes->find(item.value);
                 LUAU_ASSERT(propTy);
                 TypeId tProp = follow(*propTy);
-                if (get<BlockedType>(tProp))
+                if (DFInt::LuauTypeSolverRelease >= 648)
+                {
+                    LUAU_ASSERT(!is<BlockedType>(tKey));
+                }
+                else if (get<BlockedType>(tProp))
                     toBlock.push_back(tProp);
-
                 // Populate expected types for non-string keys declared with [] (the code below will handle the case where they are strings)
                 if (!item.key->as<AstExprConstantString>() && expectedTableTy->indexer)
                     (*astExpectedTypes)[item.key] = expectedTableTy->indexer->indexType;

Analysis/src/ToDot.cpp

@@ -269,6 +269,12 @@ void StateDot::visitChildren(TypeId ty, int index)
             finishNodeLabel(ty);
             finishNode();
         }
+        else if constexpr (std::is_same_v<T, NoRefineType>)
+        {
+            formatAppend(result, "NoRefineType %d", index);
+            finishNodeLabel(ty);
+            finishNode();
+        }
         else if constexpr (std::is_same_v<T, UnknownType>)
         {
             formatAppend(result, "UnknownType %d", index);

Analysis/src/ToString.cpp

@@ -856,6 +856,11 @@ struct TypeStringifier
         state.emit("any");
     }
 
+    void operator()(TypeId, const NoRefineType&)
+    {
+        state.emit("*no-refine*");
+    }
+
     void operator()(TypeId, const UnionType& uv)
     {
         if (state.hasSeen(&uv))

Analysis/src/Type.cpp

@@ -1030,6 +1030,7 @@ BuiltinTypes::BuiltinTypes()
     , unknownType(arena->addType(Type{UnknownType{}, /*persistent*/ true}))
     , neverType(arena->addType(Type{NeverType{}, /*persistent*/ true}))
     , errorType(arena->addType(Type{ErrorType{}, /*persistent*/ true}))
+    , noRefineType(arena->addType(Type{NoRefineType{}, /*persistent*/ true}))
     , falsyType(arena->addType(Type{UnionType{{falseType, nilType}}, /*persistent*/ true}))
     , truthyType(arena->addType(Type{NegationType{falsyType}, /*persistent*/ true}))
     , optionalNumberType(arena->addType(Type{UnionType{{numberType, nilType}}, /*persistent*/ true}))

Analysis/src/TypeAttach.cpp

@@ -145,6 +145,12 @@ public:
     {
         return allocator->alloc<AstTypeReference>(Location(), std::nullopt, AstName("any"), std::nullopt, Location());
     }
+
+    AstType* operator()(const NoRefineType&)
+    {
+        return allocator->alloc<AstTypeReference>(Location(), std::nullopt, AstName("*no-refine*"), std::nullopt, Location());
+    }
+
     AstType* operator()(const TableType& ttv)
     {
         RecursionCounter counter(&count);

Analysis/src/TypeChecker2.cpp

@@ -3022,21 +3022,10 @@ PropertyType TypeChecker2::hasIndexTypeFromType(
         if (tt->indexer)
         {
             TypeId indexType = follow(tt->indexer->indexType);
-            if (DFInt::LuauTypeSolverRelease >= 644)
-            {
             TypeId givenType = module->internalTypes.addType(SingletonType{StringSingleton{prop}});
             if (isSubtype(givenType, indexType, NotNull{module->getModuleScope().get()}, builtinTypes, *ice))
                 return {NormalizationResult::True, {tt->indexer->indexResultType}};
         }
-            else
-            {
-                if (isPrim(indexType, PrimitiveType::String))
-                    return {NormalizationResult::True, {tt->indexer->indexResultType}};
-                // If the indexer looks like { [any] : _} - the prop lookup should be allowed!
-                else if (get<AnyType>(indexType) || get<UnknownType>(indexType))
-                    return {NormalizationResult::True, {tt->indexer->indexResultType}};
-            }
-        }
 
 
         // if we are in a conditional context, we treat the property as present and `unknown` because

Analysis/src/TypeFunction.cpp

@@ -49,6 +49,7 @@ LUAU_FASTFLAGVARIABLE(DebugLuauLogTypeFamilies, false)
 LUAU_FASTFLAGVARIABLE(LuauUserDefinedTypeFunctions2, false)
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctionNoEvaluation)
 LUAU_FASTFLAG(LuauUserTypeFunFixRegister)
+LUAU_FASTFLAG(LuauRemoveNotAnyHack)
 
 LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
 
@@ -777,16 +778,8 @@ TypeFunctionReductionResult<TypeId> lenTypeFunction(
     if (normTy->hasTopTable() || get<TableType>(normalizedOperand))
         return {ctx->builtins->numberType, false, {}, {}};
 
-    if (DFInt::LuauTypeSolverRelease >= 644)
-    {
     if (auto result = tryDistributeTypeFunctionApp(lenTypeFunction, instance, typeParams, packParams, ctx))
         return *result;
-    }
-    else
-    {
-        if (auto result = tryDistributeTypeFunctionApp(notTypeFunction, instance, typeParams, packParams, ctx))
-            return *result;
-    }
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
     // the necessary state to do that, even if we intend to just eat the errors.
@@ -874,16 +867,8 @@ TypeFunctionReductionResult<TypeId> unmTypeFunction(
     if (normTy->isExactlyNumber())
         return {ctx->builtins->numberType, false, {}, {}};
 
-    if (DFInt::LuauTypeSolverRelease >= 644)
-    {
     if (auto result = tryDistributeTypeFunctionApp(unmTypeFunction, instance, typeParams, packParams, ctx))
         return *result;
-    }
-    else
-    {
-        if (auto result = tryDistributeTypeFunctionApp(notTypeFunction, instance, typeParams, packParams, ctx))
-            return *result;
-    }
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
     // the necessary state to do that, even if we intend to just eat the errors.
@@ -1810,7 +1795,6 @@ struct FindRefinementBlockers : TypeOnceVisitor
     }
 };
 
-
 TypeFunctionReductionResult<TypeId> refineTypeFunction(
     TypeId instance,
     const std::vector<TypeId>& typeParams,
@@ -1878,8 +1862,18 @@ TypeFunctionReductionResult<TypeId> refineTypeFunction(
          * We need to treat T & ~any as T in this case.
          */
         if (auto nt = get<NegationType>(discriminant))
+        {
+            if (FFlag::LuauRemoveNotAnyHack)
+            {
+                if (get<NoRefineType>(follow(nt->ty)))
+                    return {target, {}};
+            }
+            else
+            {
                 if (get<AnyType>(follow(nt->ty)))
                     return {target, {}};
+            }
+        }
 
         // If the target type is a table, then simplification already implements the logic to deal with refinements properly since the
         // type of the discriminant is guaranteed to only ever be an (arbitrarily-nested) table of a single property type.
@@ -2059,6 +2053,15 @@ TypeFunctionReductionResult<TypeId> intersectTypeFunction(
     for (auto ty : typeParams)
         types.emplace_back(follow(ty));
 
+    if (FFlag::LuauRemoveNotAnyHack)
+    {
+        // if we only have two parameters and one is `*no-refine*`, we're all done.
+        if (types.size() == 2 && get<NoRefineType>(types[1]))
+            return {types[0], false, {}, {}};
+        else if (types.size() == 2 && get<NoRefineType>(types[0]))
+            return {types[1], false, {}, {}};
+    }
+
     // check to see if the operand types are resolved enough, and wait to reduce if not
     // if any of them are `never`, the intersection will always be `never`, so we can reduce directly.
     for (auto ty : types)
@@ -2073,6 +2076,10 @@ TypeFunctionReductionResult<TypeId> intersectTypeFunction(
     TypeId resultTy = ctx->builtins->unknownType;
     for (auto ty : types)
     {
+        // skip any `*no-refine*` types.
+        if (FFlag::LuauRemoveNotAnyHack && get<NoRefineType>(ty))
+            continue;
+
         SimplifyResult result = simplifyIntersection(ctx->builtins, ctx->arena, resultTy, ty);
         if (!result.blockedTypes.empty())
             return {std::nullopt, false, {result.blockedTypes.begin(), result.blockedTypes.end()}, {}};

Analysis/src/TypeFunctionRuntime.cpp

@@ -16,6 +16,7 @@
 LUAU_DYNAMIC_FASTINT(LuauTypeFunctionSerdeIterationLimit)
 LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
 LUAU_FASTFLAGVARIABLE(LuauUserTypeFunFixRegister, false)
+LUAU_FASTFLAGVARIABLE(LuauUserTypeFunFixNoReadWrite, false)
 
 namespace Luau
 {
@@ -634,6 +635,8 @@ static int readTableProp(lua_State* L)
     auto prop = tftt->props.at(tfsst->value);
     if (prop.readTy)
         allocTypeUserData(L, (*prop.readTy)->type);
+    else if (FFlag::LuauUserTypeFunFixNoReadWrite)
+        lua_pushnil(L);
     else
         luaL_error(L, "type.readproperty: property %s is write-only, and therefore does not have a read type.", tfsst->value.c_str());
 
@@ -672,6 +675,8 @@ static int writeTableProp(lua_State* L)
     auto prop = tftt->props.at(tfsst->value);
     if (prop.writeTy)
         allocTypeUserData(L, (*prop.writeTy)->type);
+    else if (FFlag::LuauUserTypeFunFixNoReadWrite)
+        lua_pushnil(L);
     else
         luaL_error(L, "type.writeproperty: property %s is read-only, and therefore does not have a write type.", tfsst->value.c_str());
 

Analysis/src/TypeUtils.cpp

@@ -479,4 +479,68 @@ ErrorSuppression shouldSuppressErrors(NotNull<Normalizer> normalizer, TypePackId
     return result;
 }
 
+bool isLiteral(const AstExpr* expr)
+{
+    return (
+        expr->is<AstExprTable>() || expr->is<AstExprFunction>() || expr->is<AstExprConstantNumber>() || expr->is<AstExprConstantString>() ||
+        expr->is<AstExprConstantBool>() || expr->is<AstExprConstantNil>()
+    );
+}
+/**
+ * Visitor which, given an expression and a mapping from expression to TypeId,
+ * determines if there are any literal expressions that contain blocked types.
+ * This is used for bi-directional inference: we want to "apply" a type from
+ * a function argument or a type annotation to a literal.
+ */
+class BlockedTypeInLiteralVisitor : public AstVisitor
+{
+public:
+    explicit BlockedTypeInLiteralVisitor(NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes, NotNull<std::vector<TypeId>> toBlock)
+        : astTypes_{astTypes}
+        , toBlock_{toBlock}
+    {
+    }
+    bool visit(AstNode*) override
+    {
+        return false;
+    }
+
+    bool visit(AstExpr* e) override
+    {
+        auto ty = astTypes_->find(e);
+        if (ty && (get<BlockedType>(follow(*ty)) != nullptr))
+        {
+            toBlock_->push_back(*ty);
+        }
+        return isLiteral(e) || e->is<AstExprGroup>();
+    }
+
+private:
+    NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes_;
+    NotNull<std::vector<TypeId>> toBlock_;
+};
+
+std::vector<TypeId> findBlockedTypesIn(AstExprTable* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes)
+{
+    std::vector<TypeId> toBlock;
+    BlockedTypeInLiteralVisitor v{astTypes, NotNull{&toBlock}};
+    expr->visit(&v);
+    return toBlock;
+}
+
+std::vector<TypeId> findBlockedArgTypesIn(AstExprCall* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes)
+{
+    std::vector<TypeId> toBlock;
+    BlockedTypeInLiteralVisitor v{astTypes, NotNull{&toBlock}};
+    for (auto arg: expr->args)
+    {
+        if (isLiteral(arg) || arg->is<AstExprGroup>())
+        {
+            arg->visit(&v);
+        }
+    }
+    return toBlock;
+}
+
+
 } // namespace Luau

Ast/src/Parser.cpp

@@ -188,9 +188,18 @@ Parser::Parser(const char* buffer, size_t bufferSize, AstNameTable& names, Alloc
     functionStack.reserve(8);
     functionStack.push_back(top);
 
+    if (FFlag::LuauAllowFragmentParsing)
+    {
+        nameSelf = names.getOrAdd("self");
+        nameNumber = names.getOrAdd("number");
+        nameError = names.getOrAdd(kParseNameError);
+    }
+    else
+    {
         nameSelf = names.addStatic("self");
         nameNumber = names.addStatic("number");
         nameError = names.addStatic(kParseNameError);
+    }
     nameNil = names.getOrAdd("nil"); // nil is a reserved keyword
 
     matchRecoveryStopOnToken.assign(Lexeme::Type::Reserved_END, 0);

VM/src/ldo.cpp

@@ -17,8 +17,6 @@
 
 #include <string.h>
 
-LUAU_FASTFLAGVARIABLE(LuauErrorResumeCleanupArgs, false)
-
 /*
 ** {======================================================
 ** Error-recovery functions
@@ -430,11 +428,7 @@ static void resume_handle(lua_State* L, void* ud)
 
 static int resume_error(lua_State* L, const char* msg, int narg)
 {
-    if (FFlag::LuauErrorResumeCleanupArgs)
     L->top -= narg;
-    else
-        L->top = L->ci->base;
-
     setsvalue(L, L->top, luaS_new(L, msg));
     incr_top(L);
     return LUA_ERRRUN;

VM/src/lmathlib.cpp

@@ -7,6 +7,8 @@
 #include <math.h>
 #include <time.h>
 
+LUAU_FASTFLAGVARIABLE(LuauMathMap, false)
+
 #undef PI
 #define PI (3.14159265358979323846)
 #define RADIANS_PER_DEGREE (PI / 180.0)
@@ -403,6 +405,19 @@ static int math_round(lua_State* L)
     return 1;
 }
 
+static int math_map(lua_State* L)
+{
+    double x = luaL_checknumber(L, 1);
+    double inmin = luaL_checknumber(L, 2);
+    double inmax = luaL_checknumber(L, 3);
+    double outmin = luaL_checknumber(L, 4);
+    double outmax = luaL_checknumber(L, 5);
+
+    double result = outmin + (x - inmin) * (outmax - outmin) / (inmax - inmin);
+    lua_pushnumber(L, result);
+    return 1;
+}
+
 static const luaL_Reg mathlib[] = {
     {"abs", math_abs},
     {"acos", math_acos},
@@ -455,5 +470,12 @@ int luaopen_math(lua_State* L)
     lua_setfield(L, -2, "pi");
     lua_pushnumber(L, HUGE_VAL);
     lua_setfield(L, -2, "huge");
+
+    if (FFlag::LuauMathMap)
+    {
+        lua_pushcfunction(L, math_map, "map");
+        lua_setfield(L, -2, "map");
+    }
+
     return 1;
 }

bench/bench.py

@@ -508,9 +508,6 @@ def runTest(subdir, filename, filepath):
     filepath = os.path.abspath(filepath)
 
     mainVm = os.path.abspath(arguments.vm)
-    if not os.path.isfile(mainVm):
-        print(f"{colored(Color.RED, 'ERROR')}: VM executable '{mainVm}' does not exist.")
-        sys.exit(1)
 
     # Process output will contain the test name and execution times
     mainOutput = getVmOutput(substituteArguments(mainVm, getExtraArguments(filepath)) + " " + filepath)
@@ -890,11 +887,9 @@ def run(args, argsubcb):
             analyzeResult('', mainResult, compareResults)
     else:
         all_files = [subdir + os.sep + filename for subdir, dirs, files in os.walk(arguments.folder) for filename in files]
-        if len(all_files) == 0:
-            print(f"{colored(Color.YELLOW, 'WARNING')}: No test files found in '{arguments.folder}'.")
         for filepath in sorted(all_files):
             subdir, filename = os.path.split(filepath)
-            if filename.endswith(".lua") or filename.endswith(".luau"):
+            if filename.endswith(".lua"):
                 if arguments.run_test == None or re.match(arguments.run_test, filename[:-4]):
                     runTest(subdir, filename, filepath)
 

tests/Conformance.test.cpp

@@ -31,6 +31,7 @@ extern int optimizationLevel;
 void luaC_fullgc(lua_State* L);
 void luaC_validate(lua_State* L);
 
+LUAU_FASTFLAG(LuauMathMap)
 LUAU_FASTFLAG(DebugLuauAbortingChecks)
 LUAU_FASTINT(CodegenHeuristicsInstructionLimit)
 LUAU_FASTFLAG(LuauNativeAttribute)
@@ -652,6 +653,8 @@ TEST_CASE("Buffers")
 
 TEST_CASE("Math")
 {
+    ScopedFastFlag LuauMathMap{FFlag::LuauMathMap, true};
+
     runConformance("math.lua");
 }
 

tests/FragmentAutocomplete.test.cpp

@@ -4,10 +4,13 @@
 #include "Fixture.h"
 #include "Luau/Ast.h"
 #include "Luau/AstQuery.h"
+#include "Luau/Common.h"
 
 
 using namespace Luau;
 
+LUAU_FASTFLAG(LuauAllowFragmentParsing);
+
 struct FragmentAutocompleteFixture : Fixture
 {
 
@@ -17,9 +20,25 @@ struct FragmentAutocompleteFixture : Fixture
         REQUIRE(p.root);
         return findAncestryForFragmentParse(p.root, cursorPos);
     }
+
+    CheckResult checkBase(const std::string& document)
+    {
+        ScopedFastFlag sff{FFlag::LuauSolverV2, true};
+        FrontendOptions opts;
+        opts.retainFullTypeGraphs = true;
+        return this->frontend.check("MainModule", opts);
+    }
+
+    FragmentParseResult parseFragment(const std::string& document, const Position& cursorPos)
+    {
+        ScopedFastFlag sffs[]{{FFlag::LuauAllowFragmentParsing, true}, {FFlag::LuauSolverV2, true}};
+        SourceModule* srcModule = this->getMainSourceModule();
+        std::string_view srcString = document;
+        return Luau::parseFragment(*srcModule, srcString, cursorPos);
+    }
 };
 
-TEST_SUITE_BEGIN("FragmentAutocompleteTraversalTest");
+TEST_SUITE_BEGIN("FragmentAutocompleteTraversalTests");
 
 TEST_CASE_FIXTURE(FragmentAutocompleteFixture, "just_two_locals")
 {
@@ -32,7 +51,7 @@ local y = 5
     );
 
     CHECK_EQ(3, result.ancestry.size());
-    CHECK_EQ(2, result.localStack.size());
+    CHECK_EQ(1, result.localStack.size());
     CHECK_EQ(result.localMap.size(), result.localStack.size());
     REQUIRE(result.nearestStatement);
 
@@ -56,10 +75,10 @@ end
     );
 
     CHECK_EQ(5, result.ancestry.size());
-    CHECK_EQ(3, result.localStack.size());
+    CHECK_EQ(2, result.localStack.size());
     CHECK_EQ(result.localMap.size(), result.localStack.size());
     REQUIRE(result.nearestStatement);
-    CHECK_EQ("e", std::string(result.localStack.back()->name.value));
+    CHECK_EQ("y", std::string(result.localStack.back()->name.value));
 
     AstStatLocal* local = result.nearestStatement->as<AstStatLocal>();
     REQUIRE(local);
@@ -85,10 +104,10 @@ end
     );
 
     CHECK_EQ(6, result.ancestry.size());
-    CHECK_EQ(4, result.localStack.size());
+    CHECK_EQ(3, result.localStack.size());
     CHECK_EQ(result.localMap.size(), result.localStack.size());
     REQUIRE(result.nearestStatement);
-    CHECK_EQ("q", std::string(result.localStack.back()->name.value));
+    CHECK_EQ("z", std::string(result.localStack.back()->name.value));
 
     AstStatLocal* local = result.nearestStatement->as<AstStatLocal>();
     REQUIRE(local);
@@ -129,11 +148,122 @@ local function bar() return x + foo() end
     );
 
     CHECK_EQ(8, result.ancestry.size());
-    CHECK_EQ(3, result.localStack.size());
+    CHECK_EQ(2, result.localStack.size());
     CHECK_EQ(result.localMap.size(), result.localStack.size());
-    CHECK_EQ("bar", std::string(result.localStack.back()->name.value));
+    CHECK_EQ("x", std::string(result.localStack.back()->name.value));
     auto returnSt = result.nearestStatement->as<AstStatReturn>();
     CHECK(returnSt != nullptr);
 }
 
 TEST_SUITE_END();
+
+
+TEST_SUITE_BEGIN("FragmentAutocompleteParserTests");
+
+TEST_CASE_FIXTURE(FragmentAutocompleteFixture, "statement_in_empty_fragment_is_non_null")
+{
+    auto res = check(R"(
+
+)");
+
+    LUAU_REQUIRE_NO_ERRORS(res);
+
+    auto fragment = parseFragment(
+        R"(
+
+)",
+        Position(1, 0)
+    );
+    CHECK_EQ("\n", fragment.fragmentToParse);
+    CHECK_EQ(2, fragment.ancestry.size());
+    REQUIRE(fragment.root);
+    CHECK_EQ(0, fragment.root->body.size);
+    auto statBody = fragment.root->as<AstStatBlock>();
+    CHECK(statBody != nullptr);
+}
+
+TEST_CASE_FIXTURE(FragmentAutocompleteFixture, "can_parse_complete_fragments")
+{
+    auto res = check(
+        R"(
+local x = 4
+local y = 5
+)"
+    );
+
+    LUAU_REQUIRE_NO_ERRORS(res);
+
+    auto fragment = parseFragment(
+        R"(
+local x = 4
+local y = 5
+local z = x + y
+)",
+        Position{3, 15}
+    );
+
+    CHECK_EQ("\nlocal z = x + y", fragment.fragmentToParse);
+    CHECK_EQ(5, fragment.ancestry.size());
+    REQUIRE(fragment.root);
+    CHECK_EQ(1, fragment.root->body.size);
+    auto stat = fragment.root->body.data[0]->as<AstStatLocal>();
+    REQUIRE(stat);
+    CHECK_EQ(1, stat->vars.size);
+    CHECK_EQ(1, stat->values.size);
+    CHECK_EQ("z", std::string(stat->vars.data[0]->name.value));
+
+    auto bin = stat->values.data[0]->as<AstExprBinary>();
+    REQUIRE(bin);
+    CHECK_EQ(AstExprBinary::Op::Add, bin->op);
+
+    auto lhs = bin->left->as<AstExprLocal>();
+    auto rhs = bin->right->as<AstExprLocal>();
+    REQUIRE(lhs);
+    REQUIRE(rhs);
+    CHECK_EQ("x", std::string(lhs->local->name.value));
+    CHECK_EQ("y", std::string(rhs->local->name.value));
+}
+
+TEST_CASE_FIXTURE(FragmentAutocompleteFixture, "can_parse_fragments_in_line")
+{
+    auto res = check(
+        R"(
+local x = 4
+local y = 5
+)"
+    );
+
+    LUAU_REQUIRE_NO_ERRORS(res);
+
+    auto fragment = parseFragment(
+        R"(
+local x = 4
+local z = x + y
+local y = 5
+)",
+        Position{2, 15}
+    );
+
+    CHECK_EQ("local z = x + y", fragment.fragmentToParse);
+    CHECK_EQ(5, fragment.ancestry.size());
+    REQUIRE(fragment.root);
+    CHECK_EQ(1, fragment.root->body.size);
+    auto stat = fragment.root->body.data[0]->as<AstStatLocal>();
+    REQUIRE(stat);
+    CHECK_EQ(1, stat->vars.size);
+    CHECK_EQ(1, stat->values.size);
+    CHECK_EQ("z", std::string(stat->vars.data[0]->name.value));
+
+    auto bin = stat->values.data[0]->as<AstExprBinary>();
+    REQUIRE(bin);
+    CHECK_EQ(AstExprBinary::Op::Add, bin->op);
+
+    auto lhs = bin->left->as<AstExprLocal>();
+    auto rhs = bin->right->as<AstExprGlobal>();
+    REQUIRE(lhs);
+    REQUIRE(rhs);
+    CHECK_EQ("x", std::string(lhs->local->name.value));
+    CHECK_EQ("y", std::string(rhs->name.value));
+}
+
+TEST_SUITE_END();

tests/Repl.test.cpp

@@ -3,6 +3,7 @@
 #include "lualib.h"
 
 #include "Repl.h"
+#include "ScopedFlags.h"
 
 #include "doctest.h"
 
@@ -12,6 +13,8 @@
 #include <string>
 #include <vector>
 
+LUAU_FASTFLAG(LuauMathMap)
+
 struct Completion
 {
     std::string completion;
@@ -172,15 +175,17 @@ TEST_CASE_FIXTURE(ReplFixture, "CompleteGlobalVariables")
         CHECK(checkCompletion(completions, prefix, "myvariable1"));
         CHECK(checkCompletion(completions, prefix, "myvariable2"));
     }
+    if (FFlag::LuauMathMap)
     {
         // Try completing some builtin functions
         CompletionSet completions = getCompletionSet("math.m");
 
         std::string prefix = "math.";
-        CHECK(completions.size() == 3);
+        CHECK(completions.size() == 4);
         CHECK(checkCompletion(completions, prefix, "max("));
         CHECK(checkCompletion(completions, prefix, "min("));
         CHECK(checkCompletion(completions, prefix, "modf("));
+        CHECK(checkCompletion(completions, prefix, "map("));
     }
 }
 

tests/TypeFunction.user.test.cpp

@@ -12,6 +12,7 @@ LUAU_FASTFLAG(LuauUserDefinedTypeFunctionsSyntax2)
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctions2)
 LUAU_FASTFLAG(LuauUserDefinedTypeFunctionNoEvaluation)
 LUAU_FASTFLAG(LuauUserTypeFunFixRegister)
+LUAU_FASTFLAG(LuauUserTypeFunFixNoReadWrite)
 
 TEST_SUITE_BEGIN("UserDefinedTypeFunctionTests");
 
@@ -674,6 +675,36 @@ TEST_CASE_FIXTURE(ClassFixture, "udtf_class_methods_works")
     CHECK(toString(tpm->givenTp) == "{ BaseField: number, read BaseMethod: (BaseClass, number) -> (), read Touched: Connection }");
 }
 
+TEST_CASE_FIXTURE(ClassFixture, "write_of_readonly_is_nil")
+{
+    ScopedFastFlag newSolver{FFlag::LuauSolverV2, true};
+    ScopedFastFlag udtfSyntax{FFlag::LuauUserDefinedTypeFunctionsSyntax2, true};
+    ScopedFastFlag udtf{FFlag::LuauUserDefinedTypeFunctions2, true};
+    ScopedFastFlag udtfRwFix{FFlag::LuauUserTypeFunFixNoReadWrite, true};
+
+
+    CheckResult result = check(R"(
+        type function getclass(arg)
+            local props = arg:properties()
+            local table = types.newtable(props)
+            local singleton = types.singleton("BaseMethod")
+
+            if table:writeproperty(singleton) then
+                return types.singleton(true)
+            else
+                return types.singleton(false)
+            end
+        end
+        -- forcing an error here to check the exact type of the metatable
+        local function ok(idx: getclass<BaseClass>): nil return idx end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+    TypePackMismatch* tpm = get<TypePackMismatch>(result.errors[0]);
+    REQUIRE(tpm);
+    CHECK(toString(tpm->givenTp) == "false");
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "udtf_check_mutability")
 {
     ScopedFastFlag newSolver{FFlag::LuauSolverV2, true};

tests/TypeInfer.tables.test.cpp

@@ -4891,4 +4891,41 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "metatable_union_type")
     );
 }
 
+TEST_CASE_FIXTURE(Fixture, "function_check_constraint_too_eager")
+{
+    ScopedFastFlag _{FFlag::LuauSolverV2, true};
+
+    // CLI-121540: All of these examples should have no errors.
+
+    LUAU_CHECK_ERROR_COUNT(3, check(R"(
+        local function doTheThing(_: { [string]: unknown }) end
+        doTheThing({
+            ['foo'] = 5,
+            ['bar'] = 'heyo',
+        })
+    )"));
+
+    LUAU_CHECK_ERROR_COUNT(1, check(R"(
+        type Input = { [string]: unknown }
+
+        local i : Input = {
+            [('%s'):format('3.14')]=5,
+            ['stringField']='Heyo'
+        }
+    )"));
+
+    // This example previously asserted due to eagerly mutating the underlying
+    // table type.
+    LUAU_CHECK_ERROR_COUNT(3, check(R"(
+        type Input = { [string]: unknown }
+
+        local function doTheThing(_: Input) end
+
+        doTheThing({
+            [('%s'):format('3.14')]=5,
+            ['stringField']='Heyo'
+        })
+    )"));
+}
+
 TEST_SUITE_END();

tests/TypeInfer.test.cpp

@@ -1683,4 +1683,27 @@ TEST_CASE_FIXTURE(Fixture, "leading_ampersand_no_type")
     CHECK("*error-type*" == toString(requireTypeAlias("Amp")));
 }
 
+TEST_CASE_FIXTURE(Fixture, "react_lua_follow_free_type_ub")
+{
+    ScopedFastFlag _{FFlag::LuauSolverV2, true};
+
+    LUAU_REQUIRE_NO_ERRORS(check(R"(
+        return function(Roact)
+            local Tree = Roact.Component:extend("Tree")
+
+            function Tree:render()
+                local breadth, components, depth, id, wrap =
+                    self.props.breadth, self.props.components, self.props.depth, self.props.id, self.props.wrap
+                local Box = components.Box
+                if depth == 0 then
+                    Roact.createElement(Box, {})
+                else
+                    Roact.createElement(Tree, {})
+                end
+
+            end
+        end
+    )"));
+}
+
 TEST_SUITE_END();

tests/conformance/math.lua

@@ -388,6 +388,20 @@ assert(math.pow(noinline(2), 2) == 4)
 assert(math.pow(noinline(4), 0.5) == 2)
 assert(math.pow(noinline(-2), 2) == 4)
 
+-- map
+assert(math.map(0, -1, 1, 0, 2) == 1)
+assert(math.map(1, 1, 4, 0, 2) == 0)
+assert(math.map(2.5, 1, 4, 0, 2) == 1)
+assert(math.map(4, 1, 4, 0, 2) == 2)
+assert(math.map(1, 1, 4, 2, 0) == 2)
+assert(math.map(2.5, 1, 4, 2, 0) == 1)
+assert(math.map(4, 1, 4, 2, 0) == 0)
+assert(math.map(1, 4, 1, 2, 0) == 0)
+assert(math.map(2.5, 4, 1, 2, 0) == 1)
+assert(math.map(4, 4, 1, 2, 0) == 2)
+assert(math.map(-8, 0, 4, 0, 2) == -4)
+assert(math.map(16, 0, 4, 0, 2) == 8)
+
 assert(tostring(math.pow(-2, 0.5)) == "nan")
 
 -- test that fastcalls return correct number of results