Sync to upstream/release/625

Analysis/include/Luau/Constraint.h

@@ -284,11 +284,13 @@ struct Constraint
 
     std::vector<NotNull<Constraint>> dependencies;
 
-    DenseHashSet<TypeId> getFreeTypes() const;
+    DenseHashSet<TypeId> getMaybeMutatedFreeTypes() const;
 };
 
 using ConstraintPtr = std::unique_ptr<Constraint>;
 
+bool isReferenceCountedType(const TypeId typ);
+
 inline Constraint& asMutable(const Constraint& c)
 {
     return const_cast<Constraint&>(c);

Analysis/include/Luau/ConstraintSolver.h

@@ -242,6 +242,24 @@ struct ConstraintSolver
     void reportError(TypeErrorData&& data, const Location& location);
     void reportError(TypeError e);
 
+    /**
+     * Shifts the count of references from `source` to `target`. This should be paired
+     * with any instance of binding a free type in order to maintain accurate refcounts.
+     * If `target` is not a free type, this is a noop.
+     * @param source the free type which is being bound
+     * @param target the type which the free type is being bound to
+     */
+    void shiftReferences(TypeId source, TypeId target);
+
+    /**
+     * Generalizes the given free type if the reference counting allows it.
+     * @param the scope to generalize in
+     * @param type the free type we want to generalize
+     * @returns a non-free type that generalizes the argument, or `std::nullopt` if one
+     * does not exist
+     */
+    std::optional<TypeId> generalizeFreeType(NotNull<Scope> scope, TypeId type);
+
     /**
      * Checks the existing set of constraints to see if there exist any that contain
      * the provided free type, indicating that it is not yet ready to be replaced by

Analysis/include/Luau/Normalize.h

@@ -307,6 +307,9 @@ struct NormalizedType
     /// Returns true if the type is a subtype of string(it could be a singleton). Behaves like Type::isString()
     bool isSubtypeOfString() const;
 
+    /// Returns true if the type is a subtype of boolean(it could be a singleton). Behaves like Type::isBoolean()
+    bool isSubtypeOfBooleans() const;
+
     /// Returns true if this type should result in error suppressing behavior.
     bool shouldSuppressErrors() const;
 
@@ -360,7 +363,6 @@ public:
     Normalizer& operator=(Normalizer&) = delete;
 
     // If this returns null, the typechecker should emit a "too complex" error
-    const NormalizedType* DEPRECATED_normalize(TypeId ty);
     std::shared_ptr<const NormalizedType> normalize(TypeId ty);
     void clearNormal(NormalizedType& norm);
 
@@ -395,7 +397,7 @@ public:
     TypeId negate(TypeId there);
     void subtractPrimitive(NormalizedType& here, TypeId ty);
     void subtractSingleton(NormalizedType& here, TypeId ty);
-    NormalizationResult intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect, bool useDeprecated = false);
+    NormalizationResult intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect);
 
     // ------- Normalizing intersections
     TypeId intersectionOfTops(TypeId here, TypeId there);
@@ -404,8 +406,8 @@ public:
     void intersectClassesWithClass(NormalizedClassType& heres, TypeId there);
     void intersectStrings(NormalizedStringType& here, const NormalizedStringType& there);
     std::optional<TypePackId> intersectionOfTypePacks(TypePackId here, TypePackId there);
-    std::optional<TypeId> intersectionOfTables(TypeId here, TypeId there);
+    std::optional<TypeId> intersectionOfTables(TypeId here, TypeId there, Set<TypeId>& seenSet);
-    void intersectTablesWithTable(TypeIds& heres, TypeId there);
+    void intersectTablesWithTable(TypeIds& heres, TypeId there, Set<TypeId>& seenSetTypes);
     void intersectTables(TypeIds& heres, const TypeIds& theres);
     std::optional<TypeId> intersectionOfFunctions(TypeId here, TypeId there);
     void intersectFunctionsWithFunction(NormalizedFunctionType& heress, TypeId there);
@@ -413,7 +415,7 @@ public:
     NormalizationResult intersectTyvarsWithTy(NormalizedTyvars& here, TypeId there, Set<TypeId>& seenSetTypes);
     NormalizationResult intersectNormals(NormalizedType& here, const NormalizedType& there, int ignoreSmallerTyvars = -1);
     NormalizationResult intersectNormalWithTy(NormalizedType& here, TypeId there, Set<TypeId>& seenSetTypes);
-    NormalizationResult normalizeIntersections(const std::vector<TypeId>& intersections, NormalizedType& outType);
+    NormalizationResult normalizeIntersections(const std::vector<TypeId>& intersections, NormalizedType& outType, Set<TypeId>& seenSet);
 
     // Check for inhabitance
     NormalizationResult isInhabited(TypeId ty);
@@ -423,6 +425,7 @@ public:
 
     // Check for intersections being inhabited
     NormalizationResult isIntersectionInhabited(TypeId left, TypeId right);
+    NormalizationResult isIntersectionInhabited(TypeId left, TypeId right, Set<TypeId>& seenSet);
 
     // -------- Convert back from a normalized type to a type
     TypeId typeFromNormal(const NormalizedType& norm);

Analysis/include/Luau/Set.h

@@ -4,7 +4,6 @@
 #include "Luau/Common.h"
 #include "Luau/DenseHash.h"
 
-LUAU_FASTFLAG(LuauFixSetIter)
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
 
 namespace Luau
@@ -142,13 +141,10 @@ public:
         const_iterator(typename Impl::const_iterator impl_, typename Impl::const_iterator end_)
             : impl(impl_)
             , end(end_)
-        {
-            if (FFlag::LuauFixSetIter || FFlag::DebugLuauDeferredConstraintResolution)
         {
             while (impl != end && impl->second == false)
                 ++impl;
         }
-        }
 
         const T& operator*() const
         {

Analysis/include/Luau/Unifier2.h

@@ -78,6 +78,11 @@ struct Unifier2
     bool unify(TableType* subTable, const TableType* superTable);
     bool unify(const MetatableType* subMetatable, const MetatableType* superMetatable);
 
+    bool unify(const AnyType* subAny, const FunctionType* superFn);
+    bool unify(const FunctionType* subFn, const AnyType* superAny);
+    bool unify(const AnyType* subAny, const TableType* superTable);
+    bool unify(const TableType* subTable, const AnyType* superAny);
+
     // TODO think about this one carefully.  We don't do unions or intersections of type packs
     bool unify(TypePackId subTp, TypePackId superTp);
 

Analysis/src/Constraint.cpp

@@ -13,12 +13,12 @@ Constraint::Constraint(NotNull<Scope> scope, const Location& location, Constrain
 {
 }
 
-struct FreeTypeCollector : TypeOnceVisitor
+struct ReferenceCountInitializer : TypeOnceVisitor
 {
 
     DenseHashSet<TypeId>* result;
 
-    FreeTypeCollector(DenseHashSet<TypeId>* result)
+    ReferenceCountInitializer(DenseHashSet<TypeId>* result)
         : result(result)
     {
     }
@@ -29,6 +29,18 @@ struct FreeTypeCollector : TypeOnceVisitor
         return false;
     }
 
+    bool visit(TypeId ty, const BlockedType&) override
+    {
+        result->insert(ty);
+        return false;
+    }
+
+    bool visit(TypeId ty, const PendingExpansionType&) override
+    {
+        result->insert(ty);
+        return false;
+    }
+
     bool visit(TypeId ty, const ClassType&) override
     {
         // ClassTypes never contain free types.
@@ -36,26 +48,92 @@ struct FreeTypeCollector : TypeOnceVisitor
     }
 };
 
-DenseHashSet<TypeId> Constraint::getFreeTypes() const
+bool isReferenceCountedType(const TypeId typ)
+{
+    // n.b. this should match whatever `ReferenceCountInitializer` includes.
+    return get<FreeType>(typ) || get<BlockedType>(typ) || get<PendingExpansionType>(typ);
+}
+
+DenseHashSet<TypeId> Constraint::getMaybeMutatedFreeTypes() const
 {
     DenseHashSet<TypeId> types{{}};
-    FreeTypeCollector ftc{&types};
+    ReferenceCountInitializer rci{&types};
 
-    if (auto sc = get<SubtypeConstraint>(*this))
+    if (auto ec = get<EqualityConstraint>(*this))
     {
-        ftc.traverse(sc->subType);
+        rci.traverse(ec->resultType);
-        ftc.traverse(sc->superType);
+        // `EqualityConstraints` should not mutate `assignmentType`.
+    }
+    else if (auto sc = get<SubtypeConstraint>(*this))
+    {
+        rci.traverse(sc->subType);
+        rci.traverse(sc->superType);
     }
     else if (auto psc = get<PackSubtypeConstraint>(*this))
     {
-        ftc.traverse(psc->subPack);
+        rci.traverse(psc->subPack);
-        ftc.traverse(psc->superPack);
+        rci.traverse(psc->superPack);
+    }
+    else if (auto gc = get<GeneralizationConstraint>(*this))
+    {
+        rci.traverse(gc->generalizedType);
+        // `GeneralizationConstraints` should not mutate `sourceType` or `interiorTypes`.
+    }
+    else if (auto itc = get<IterableConstraint>(*this))
+    {
+        rci.traverse(itc->variables);
+        // `IterableConstraints` should not mutate `iterator`.
+    }
+    else if (auto nc = get<NameConstraint>(*this))
+    {
+        rci.traverse(nc->namedType);
+    }
+    else if (auto taec = get<TypeAliasExpansionConstraint>(*this))
+    {
+        rci.traverse(taec->target);
     }
     else if (auto ptc = get<PrimitiveTypeConstraint>(*this))
     {
-        // we need to take into account primitive type constraints to prevent type families from reducing on
+        rci.traverse(ptc->freeType);
-        // primitive whose types we have not yet selected to be singleton or not.
+    }
-        ftc.traverse(ptc->freeType);
+    else if (auto hpc = get<HasPropConstraint>(*this))
+    {
+        rci.traverse(hpc->resultType);
+        // `HasPropConstraints` should not mutate `subjectType`.
+    }
+    else if (auto spc = get<SetPropConstraint>(*this))
+    {
+        rci.traverse(spc->resultType);
+        // `SetPropConstraints` should not mutate `subjectType` or `propType`.
+        // TODO: is this true? it "unifies" with `propType`, so maybe mutates that one too?
+    }
+    else if (auto hic = get<HasIndexerConstraint>(*this))
+    {
+        rci.traverse(hic->resultType);
+        // `HasIndexerConstraint` should not mutate `subjectType` or `indexType`.
+    }
+    else if (auto sic = get<SetIndexerConstraint>(*this))
+    {
+        rci.traverse(sic->propType);
+        // `SetIndexerConstraints` should not mutate `subjectType` or `indexType`.
+    }
+    else if (auto uc = get<UnpackConstraint>(*this))
+    {
+        rci.traverse(uc->resultPack);
+        // `UnpackConstraint` should not mutate `sourcePack`.
+    }
+    else if (auto u1c = get<Unpack1Constraint>(*this))
+    {
+        rci.traverse(u1c->resultType);
+        // `Unpack1Constraint` should not mutate `sourceType`.
+    }
+    else if (auto rc = get<ReduceConstraint>(*this))
+    {
+        rci.traverse(rc->ty);
+    }
+    else if (auto rpc = get<ReducePackConstraint>(*this))
+    {
+        rci.traverse(rpc->tp);
     }
 
     return types;

Analysis/src/ConstraintSolver.cpp

@@ -27,6 +27,7 @@
 #include <utility>
 
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolver, false);
+LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverIncludeDependencies, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogBindings, false);
 LUAU_FASTINTVARIABLE(LuauSolverRecursionLimit, 500);
 
@@ -251,6 +252,15 @@ void dump(ConstraintSolver* cs, ToStringOptions& opts)
         auto it = cs->blockedConstraints.find(c);
         int blockCount = it == cs->blockedConstraints.end() ? 0 : int(it->second);
         printf("\t%d\t%s\n", blockCount, toString(*c, opts).c_str());
+
+        if (FFlag::DebugLuauLogSolverIncludeDependencies)
+        {
+            for (NotNull<Constraint> dep : c->dependencies)
+            {
+                if (std::find(cs->unsolvedConstraints.begin(), cs->unsolvedConstraints.end(), dep) != cs->unsolvedConstraints.end())
+                    printf("\t\t|\t%s\n", toString(*dep, opts).c_str());
+            }
+        }
     }
 }
 
@@ -305,7 +315,7 @@ ConstraintSolver::ConstraintSolver(NotNull<Normalizer> normalizer, NotNull<Scope
         unsolvedConstraints.push_back(c);
 
         // initialize the reference counts for the free types in this constraint.
-        for (auto ty : c->getFreeTypes())
+        for (auto ty : c->getMaybeMutatedFreeTypes())
         {
             // increment the reference count for `ty`
             auto [refCount, _] = unresolvedConstraints.try_insert(ty, 0);
@@ -394,7 +404,7 @@ void ConstraintSolver::run()
                 unsolvedConstraints.erase(unsolvedConstraints.begin() + i);
 
                 // decrement the referenced free types for this constraint if we dispatched successfully!
-                for (auto ty : c->getFreeTypes())
+                for (auto ty : c->getMaybeMutatedFreeTypes())
                 {
                     // this is a little weird, but because we're only counting free types in subtyping constraints,
                     // some constraints (like unpack) might actually produce _more_ references to a free type.
@@ -720,8 +730,6 @@ bool ConstraintSolver::tryDispatch(const NameConstraint& c, NotNull<const Constr
     {
         // nothing (yet)
     }
-    else
-        return block(c.namedType, constraint);
 
     return true;
 }
@@ -771,6 +779,7 @@ bool ConstraintSolver::tryDispatch(const TypeAliasExpansionConstraint& c, NotNul
 
     auto bindResult = [this, &c, constraint](TypeId result) {
         LUAU_ASSERT(get<PendingExpansionType>(c.target));
+        shiftReferences(c.target, result);
         emplaceType<BoundType>(asMutable(c.target), result);
         unblock(c.target, constraint->location);
     };
@@ -1190,6 +1199,7 @@ bool ConstraintSolver::tryDispatch(const FunctionCheckConstraint& c, NotNull<con
             {
                 if (!lambdaExpr->args.data[j]->annotation && get<FreeType>(follow(lambdaArgTys[j])))
                 {
+                    shiftReferences(lambdaArgTys[j], expectedLambdaArgTys[j]);
                     emplaceType<BoundType>(asMutable(lambdaArgTys[j]), expectedLambdaArgTys[j]);
                 }
             }
@@ -1242,6 +1252,7 @@ bool ConstraintSolver::tryDispatch(const PrimitiveTypeConstraint& c, NotNull<con
     else if (expectedType && maybeSingleton(*expectedType))
         bindTo = freeType->lowerBound;
 
+    shiftReferences(c.freeType, bindTo);
     emplaceType<BoundType>(asMutable(c.freeType), bindTo);
 
     return true;
@@ -1551,7 +1562,11 @@ bool ConstraintSolver::tryDispatchHasIndexer(
         if (0 == results.size())
             emplaceType<BoundType>(asMutable(resultType), builtinTypes->errorType);
         else if (1 == results.size())
-            emplaceType<BoundType>(asMutable(resultType), *results.begin());
+        {
+            TypeId firstResult = *results.begin();
+            shiftReferences(resultType, firstResult);
+            emplaceType<BoundType>(asMutable(resultType), firstResult);
+        }
         else
             emplaceType<UnionType>(asMutable(resultType), std::vector(results.begin(), results.end()));
 
@@ -1716,7 +1731,10 @@ bool ConstraintSolver::tryDispatchUnpack1(NotNull<const Constraint> constraint,
         --lt->blockCount;
 
         if (0 == lt->blockCount)
+        {
+            shiftReferences(ty, lt->domain);
             emplaceType<BoundType>(asMutable(ty), lt->domain);
+        }
     };
 
     if (auto ut = get<UnionType>(resultTy))
@@ -1732,6 +1750,7 @@ bool ConstraintSolver::tryDispatchUnpack1(NotNull<const Constraint> constraint,
             // constitute any meaningful constraint, so we replace it
             // with a free type.
             TypeId f = freshType(arena, builtinTypes, constraint->scope);
+            shiftReferences(resultTy, f);
             emplaceType<BoundType>(asMutable(resultTy), f);
         }
         else
@@ -1798,8 +1817,11 @@ bool ConstraintSolver::tryDispatch(const UnpackConstraint& c, NotNull<const Cons
             --lt->blockCount;
 
             if (0 == lt->blockCount)
+            {
+                shiftReferences(resultTy, lt->domain);
                 emplaceType<BoundType>(asMutable(resultTy), lt->domain);
             }
+        }
         else if (get<BlockedType>(resultTy) || get<PendingExpansionType>(resultTy))
         {
             emplaceType<BoundType>(asMutable(resultTy), builtinTypes->nilType);
@@ -1977,10 +1999,13 @@ bool ConstraintSolver::tryDispatchIterableTable(TypeId iteratorTy, const Iterabl
                     LUAU_ASSERT(0 <= lt->blockCount);
 
                     if (0 == lt->blockCount)
+                    {
+                        shiftReferences(ty, lt->domain);
                         emplaceType<BoundType>(asMutable(ty), lt->domain);
                     }
                 }
             }
+        }
         else
             unpack(builtinTypes->errorType);
     }
@@ -2395,11 +2420,16 @@ void ConstraintSolver::bindBlockedType(TypeId blockedTy, TypeId resultTy, TypeId
 
         LUAU_ASSERT(freeScope);
 
-        emplaceType<BoundType>(asMutable(blockedTy), arena->freshType(freeScope));
+        TypeId freeType = arena->freshType(freeScope);
+        shiftReferences(blockedTy, freeType);
+        emplaceType<BoundType>(asMutable(blockedTy), freeType);
     }
     else
+    {
+        shiftReferences(blockedTy, resultTy);
         emplaceType<BoundType>(asMutable(blockedTy), resultTy);
     }
+}
 
 bool ConstraintSolver::block_(BlockedConstraintId target, NotNull<const Constraint> constraint)
 {
@@ -2700,10 +2730,43 @@ void ConstraintSolver::reportError(TypeError e)
     errors.back().moduleName = currentModuleName;
 }
 
+void ConstraintSolver::shiftReferences(TypeId source, TypeId target)
+{
+    target = follow(target);
+
+    // if the target isn't a reference counted type, there's nothing to do.
+    // this stops us from keeping unnecessary counts for e.g. primitive types.
+    if (!isReferenceCountedType(target))
+        return;
+
+    auto sourceRefs = unresolvedConstraints.find(source);
+    if (!sourceRefs)
+        return;
+
+    // we read out the count before proceeding to avoid hash invalidation issues.
+    size_t count = *sourceRefs;
+
+    auto [targetRefs, _] = unresolvedConstraints.try_insert(target, 0);
+    targetRefs += count;
+}
+
+std::optional<TypeId> ConstraintSolver::generalizeFreeType(NotNull<Scope> scope, TypeId type)
+{
+    if (get<FreeType>(type))
+    {
+        auto refCount = unresolvedConstraints.find(type);
+        if (!refCount || *refCount > 1)
+            return {};
+    }
+
+    Unifier2 u2{NotNull{arena}, builtinTypes, scope, NotNull{&iceReporter}};
+    return u2.generalize(type);
+}
+
 bool ConstraintSolver::hasUnresolvedConstraints(TypeId ty)
 {
     if (auto refCount = unresolvedConstraints.find(ty))
-        return *refCount > 0;
+        return *refCount > 1;
 
     return false;
 }

Analysis/src/Frontend.cpp

@@ -1297,6 +1297,30 @@ ModulePtr check(const SourceModule& sourceModule, Mode mode, const std::vector<R
     result->type = sourceModule.type;
     result->upperBoundContributors = std::move(cs.upperBoundContributors);
 
+    if (result->timeout || result->cancelled)
+    {
+        // If solver was interrupted, skip typechecking and replace all module results with error-supressing types to avoid leaking blocked/pending
+        // types
+        ScopePtr moduleScope = result->getModuleScope();
+        moduleScope->returnType = builtinTypes->errorRecoveryTypePack();
+
+        for (auto& [name, ty] : result->declaredGlobals)
+            ty = builtinTypes->errorRecoveryType();
+
+        for (auto& [name, tf] : result->exportedTypeBindings)
+            tf.type = builtinTypes->errorRecoveryType();
+    }
+    else
+    {
+        if (mode == Mode::Nonstrict)
+            Luau::checkNonStrict(builtinTypes, iceHandler, NotNull{&unifierState}, NotNull{&dfg}, NotNull{&limits}, sourceModule, result.get());
+        else
+            Luau::check(builtinTypes, NotNull{&unifierState}, NotNull{&limits}, logger.get(), sourceModule, result.get());
+    }
+
+    unfreeze(result->interfaceTypes);
+    result->clonePublicInterface(builtinTypes, *iceHandler);
+
     if (FFlag::DebugLuauForbidInternalTypes)
     {
         InternalTypeFinder finder;
@@ -1325,30 +1349,6 @@ ModulePtr check(const SourceModule& sourceModule, Mode mode, const std::vector<R
             finder.traverse(tp);
     }
 
-    if (result->timeout || result->cancelled)
-    {
-        // If solver was interrupted, skip typechecking and replace all module results with error-supressing types to avoid leaking blocked/pending
-        // types
-        ScopePtr moduleScope = result->getModuleScope();
-        moduleScope->returnType = builtinTypes->errorRecoveryTypePack();
-
-        for (auto& [name, ty] : result->declaredGlobals)
-            ty = builtinTypes->errorRecoveryType();
-
-        for (auto& [name, tf] : result->exportedTypeBindings)
-            tf.type = builtinTypes->errorRecoveryType();
-    }
-    else
-    {
-        if (mode == Mode::Nonstrict)
-            Luau::checkNonStrict(builtinTypes, iceHandler, NotNull{&unifierState}, NotNull{&dfg}, NotNull{&limits}, sourceModule, result.get());
-        else
-            Luau::check(builtinTypes, NotNull{&unifierState}, NotNull{&limits}, logger.get(), sourceModule, result.get());
-    }
-
-    unfreeze(result->interfaceTypes);
-    result->clonePublicInterface(builtinTypes, *iceHandler);
-
     // It would be nice if we could freeze the arenas before doing type
     // checking, but we'll have to do some work to get there.
     //

Analysis/src/Normalize.cpp

@@ -17,21 +17,16 @@
 
 LUAU_FASTFLAGVARIABLE(DebugLuauCheckNormalizeInvariant, false)
 LUAU_FASTFLAGVARIABLE(LuauNormalizeAwayUninhabitableTables, false)
-LUAU_FASTFLAGVARIABLE(LuauFixNormalizeCaching, false);
 LUAU_FASTFLAGVARIABLE(LuauNormalizeNotUnknownIntersection, false);
 LUAU_FASTFLAGVARIABLE(LuauFixCyclicUnionsOfIntersections, false);
 LUAU_FASTFLAGVARIABLE(LuauFixReduceStackPressure, false);
+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);
 
-static bool fixNormalizeCaching()
-{
-    return FFlag::LuauFixNormalizeCaching || FFlag::DebugLuauDeferredConstraintResolution;
-}
-
 static bool fixCyclicUnionsOfIntersections()
 {
     return FFlag::LuauFixCyclicUnionsOfIntersections || FFlag::DebugLuauDeferredConstraintResolution;
@@ -42,6 +37,11 @@ static bool fixReduceStackPressure()
     return FFlag::LuauFixReduceStackPressure || FFlag::DebugLuauDeferredConstraintResolution;
 }
 
+static bool fixCyclicTablesBlowingStack()
+{
+    return FFlag::LuauFixCyclicTablesBlowingStack || FFlag::DebugLuauDeferredConstraintResolution;
+}
+
 namespace Luau
 {
 
@@ -353,6 +353,12 @@ bool NormalizedType::isSubtypeOfString() const
            !hasBuffers() && !hasTables() && !hasFunctions() && !hasTyvars();
 }
 
+bool NormalizedType::isSubtypeOfBooleans() const
+{
+    return hasBooleans() && !hasTops() && !hasClasses() && !hasErrors() && !hasNils() && !hasNumbers() && !hasStrings() && !hasThreads() &&
+           !hasBuffers() && !hasTables() && !hasFunctions() && !hasTyvars();
+}
+
 bool NormalizedType::shouldSuppressErrors() const
 {
     return hasErrors() || get<AnyType>(tops);
@@ -561,22 +567,21 @@ NormalizationResult Normalizer::isInhabited(TypeId ty, Set<TypeId>& seen)
         return isInhabited(mtv->metatable, seen);
     }
 
-    if (fixNormalizeCaching())
-    {
     std::shared_ptr<const NormalizedType> norm = normalize(ty);
     return isInhabited(norm.get(), seen);
 }
-    else
-    {
-        const NormalizedType* norm = DEPRECATED_normalize(ty);
-        return isInhabited(norm, seen);
-    }
-}
 
 NormalizationResult Normalizer::isIntersectionInhabited(TypeId left, TypeId right)
+{
+    Set<TypeId> seen{nullptr};
+    return isIntersectionInhabited(left, right, seen);
+}
+
+NormalizationResult Normalizer::isIntersectionInhabited(TypeId left, TypeId right, Set<TypeId>& seenSet)
 {
     left = follow(left);
     right = follow(right);
+    // We're asking if intersection is inahbited between left and right but we've already seen them ....
 
     if (cacheInhabitance)
     {
@@ -584,12 +589,8 @@ NormalizationResult Normalizer::isIntersectionInhabited(TypeId left, TypeId righ
             return *result ? NormalizationResult::True : NormalizationResult::False;
     }
 
-    Set<TypeId> seen{nullptr};
-    seen.insert(left);
-    seen.insert(right);
-
     NormalizedType norm{builtinTypes};
-    NormalizationResult res = normalizeIntersections({left, right}, norm);
+    NormalizationResult res = normalizeIntersections({left, right}, norm, seenSet);
     if (res != NormalizationResult::True)
     {
         if (cacheInhabitance && res == NormalizationResult::False)
@@ -598,7 +599,7 @@ NormalizationResult Normalizer::isIntersectionInhabited(TypeId left, TypeId righ
         return res;
     }
 
-    NormalizationResult result = isInhabited(&norm, seen);
+    NormalizationResult result = isInhabited(&norm, seenSet);
 
     if (cacheInhabitance && result == NormalizationResult::True)
         cachedIsInhabitedIntersection[{left, right}] = true;
@@ -870,31 +871,6 @@ Normalizer::Normalizer(TypeArena* arena, NotNull<BuiltinTypes> builtinTypes, Not
 {
 }
 
-const NormalizedType* Normalizer::DEPRECATED_normalize(TypeId ty)
-{
-    if (!arena)
-        sharedState->iceHandler->ice("Normalizing types outside a module");
-
-    auto found = cachedNormals.find(ty);
-    if (found != cachedNormals.end())
-        return found->second.get();
-
-    NormalizedType norm{builtinTypes};
-    Set<TypeId> seenSetTypes{nullptr};
-    NormalizationResult res = unionNormalWithTy(norm, ty, seenSetTypes);
-    if (res != NormalizationResult::True)
-        return nullptr;
-    if (norm.isUnknown())
-    {
-        clearNormal(norm);
-        norm.tops = builtinTypes->unknownType;
-    }
-    std::shared_ptr<NormalizedType> shared = std::make_shared<NormalizedType>(std::move(norm));
-    const NormalizedType* result = shared.get();
-    cachedNormals[ty] = std::move(shared);
-    return result;
-}
-
 static bool isCacheable(TypeId ty, Set<TypeId>& seen);
 
 static bool isCacheable(TypePackId tp, Set<TypeId>& seen)
@@ -949,9 +925,6 @@ static bool isCacheable(TypeId ty, Set<TypeId>& seen)
 
 static bool isCacheable(TypeId ty)
 {
-    if (!fixNormalizeCaching())
-        return true;
-
     Set<TypeId> seen{nullptr};
     return isCacheable(ty, seen);
 }
@@ -985,7 +958,7 @@ std::shared_ptr<const NormalizedType> Normalizer::normalize(TypeId ty)
     return shared;
 }
 
-NormalizationResult Normalizer::normalizeIntersections(const std::vector<TypeId>& intersections, NormalizedType& outType)
+NormalizationResult Normalizer::normalizeIntersections(const std::vector<TypeId>& intersections, NormalizedType& outType, Set<TypeId>& seenSet)
 {
     if (!arena)
         sharedState->iceHandler->ice("Normalizing types outside a module");
@@ -995,7 +968,7 @@ NormalizationResult Normalizer::normalizeIntersections(const std::vector<TypeId>
     Set<TypeId> seenSetTypes{nullptr};
     for (auto ty : intersections)
     {
-        NormalizationResult res = intersectNormalWithTy(norm, ty, seenSetTypes);
+        NormalizationResult res = intersectNormalWithTy(norm, ty, seenSet);
         if (res != NormalizationResult::True)
             return res;
     }
@@ -1743,20 +1716,13 @@ bool Normalizer::withinResourceLimits()
     return true;
 }
 
-NormalizationResult Normalizer::intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect, bool useDeprecated)
+NormalizationResult Normalizer::intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect)
 {
 
     std::optional<NormalizedType> negated;
-    if (useDeprecated)
+
-    {
-        const NormalizedType* normal = DEPRECATED_normalize(toNegate);
-        negated = negateNormal(*normal);
-    }
-    else
-    {
     std::shared_ptr<const NormalizedType> normal = normalize(toNegate);
     negated = negateNormal(*normal);
-    }
 
     if (!negated)
         return NormalizationResult::False;
@@ -1911,16 +1877,8 @@ NormalizationResult Normalizer::unionNormalWithTy(NormalizedType& here, TypeId t
     {
         std::optional<NormalizedType> tn;
 
-        if (fixNormalizeCaching())
-        {
         std::shared_ptr<const NormalizedType> thereNormal = normalize(ntv->ty);
         tn = negateNormal(*thereNormal);
-        }
-        else
-        {
-            const NormalizedType* thereNormal = DEPRECATED_normalize(ntv->ty);
-            tn = negateNormal(*thereNormal);
-        }
 
         if (!tn)
             return NormalizationResult::False;
@@ -2519,7 +2477,7 @@ std::optional<TypePackId> Normalizer::intersectionOfTypePacks(TypePackId here, T
         return arena->addTypePack({});
 }
 
-std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there)
+std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there, Set<TypeId>& seenSet)
 {
     if (here == there)
         return here;
@@ -2600,8 +2558,33 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
                         // if the intersection of the read types of a property is uninhabited, the whole table is `never`.
                         if (fixReduceStackPressure())
                         {
-                            if (normalizeAwayUninhabitableTables() &&
+                            // We've seen these table prop elements before and we're about to ask if their intersection
-                                NormalizationResult::True != isIntersectionInhabited(*hprop.readTy, *tprop.readTy))
+                            // is inhabited
+                            if (fixCyclicTablesBlowingStack())
+                            {
+                                if (seenSet.contains(*hprop.readTy) && seenSet.contains(*tprop.readTy))
+                                {
+                                    seenSet.erase(*hprop.readTy);
+                                    seenSet.erase(*tprop.readTy);
+                                    return {builtinTypes->neverType};
+                                }
+                                else
+                                {
+                                    seenSet.insert(*hprop.readTy);
+                                    seenSet.insert(*tprop.readTy);
+                                }
+                            }
+
+                            NormalizationResult res = isIntersectionInhabited(*hprop.readTy, *tprop.readTy, seenSet);
+
+                            // Cleanup
+                            if (fixCyclicTablesBlowingStack())
+                            {
+                                seenSet.erase(*hprop.readTy);
+                                seenSet.erase(*tprop.readTy);
+                            }
+
+                            if (normalizeAwayUninhabitableTables() && NormalizationResult::True != res)
                                 return {builtinTypes->neverType};
                         }
                         else
@@ -2720,7 +2703,7 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
     if (tmtable && hmtable)
     {
         // NOTE: this assumes metatables are ivariant
-        if (std::optional<TypeId> mtable = intersectionOfTables(hmtable, tmtable))
+        if (std::optional<TypeId> mtable = intersectionOfTables(hmtable, tmtable, seenSet))
         {
             if (table == htable && *mtable == hmtable)
                 return here;
@@ -2750,12 +2733,12 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
         return table;
 }
 
-void Normalizer::intersectTablesWithTable(TypeIds& heres, TypeId there)
+void Normalizer::intersectTablesWithTable(TypeIds& heres, TypeId there, Set<TypeId>& seenSetTypes)
 {
     TypeIds tmp;
     for (TypeId here : heres)
     {
-        if (std::optional<TypeId> inter = intersectionOfTables(here, there))
+        if (std::optional<TypeId> inter = intersectionOfTables(here, there, seenSetTypes))
             tmp.insert(*inter);
     }
     heres.retain(tmp);
@@ -2769,7 +2752,8 @@ void Normalizer::intersectTables(TypeIds& heres, const TypeIds& theres)
     {
         for (TypeId there : theres)
         {
-            if (std::optional<TypeId> inter = intersectionOfTables(here, there))
+            Set<TypeId> seenSetTypes{nullptr};
+            if (std::optional<TypeId> inter = intersectionOfTables(here, there, seenSetTypes))
                 tmp.insert(*inter);
         }
     }
@@ -3137,7 +3121,7 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
     {
         TypeIds tables = std::move(here.tables);
         clearNormal(here);
-        intersectTablesWithTable(tables, there);
+        intersectTablesWithTable(tables, there, seenSetTypes);
         here.tables = std::move(tables);
     }
     else if (get<ClassType>(there))
@@ -3210,23 +3194,12 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
         else if (const SingletonType* stv = get<SingletonType>(t))
             subtractSingleton(here, follow(ntv->ty));
         else if (get<ClassType>(t))
-        {
-            if (fixNormalizeCaching())
         {
             NormalizationResult res = intersectNormalWithNegationTy(t, here);
             if (shouldEarlyExit(res))
                 return res;
         }
-            else
-            {
-                NormalizationResult res = intersectNormalWithNegationTy(t, here, /* useDeprecated */ true);
-                if (shouldEarlyExit(res))
-                    return res;
-            }
-        }
         else if (const UnionType* itv = get<UnionType>(t))
-        {
-            if (fixNormalizeCaching())
         {
             for (TypeId part : itv->options)
             {
@@ -3235,28 +3208,6 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
                     return res;
             }
         }
-            else
-            {
-                if (fixNormalizeCaching())
-                {
-                    for (TypeId part : itv->options)
-                    {
-                        NormalizationResult res = intersectNormalWithNegationTy(part, here);
-                        if (shouldEarlyExit(res))
-                            return res;
-                    }
-                }
-                else
-                {
-                    for (TypeId part : itv->options)
-                    {
-                        NormalizationResult res = intersectNormalWithNegationTy(part, here, /* useDeprecated */ true);
-                        if (shouldEarlyExit(res))
-                            return res;
-                    }
-                }
-            }
-        }
         else if (get<AnyType>(t))
         {
             // HACK: Refinements sometimes intersect with ~any under the

Analysis/src/Set.cpp

@@ -1,5 +0,0 @@
-// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-
-#include "Luau/Common.h"
-
-LUAU_FASTFLAGVARIABLE(LuauFixSetIter, false)

Analysis/src/ToString.cpp

@@ -20,7 +20,6 @@
 #include <string>
 
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
-LUAU_FASTFLAGVARIABLE(LuauToStringiteTypesSingleLine, false)
 
 /*
  * Enables increasing levels of verbosity for Luau type names when stringifying.

Analysis/src/TypeFamily.cpp

@@ -500,6 +500,15 @@ TypeFamilyReductionResult<TypeId> lenFamilyFn(TypeId instance, NotNull<TypeFamil
     if (isPending(operandTy, ctx->solver) || get<LocalType>(operandTy))
         return {std::nullopt, false, {operandTy}, {}};
 
+    // if the type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> maybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, operandTy);
+        if (!maybeGeneralized)
+            return {std::nullopt, false, {operandTy}, {}};
+        operandTy = *maybeGeneralized;
+    }
+
     std::shared_ptr<const NormalizedType> normTy = ctx->normalizer->normalize(operandTy);
     NormalizationResult inhabited = ctx->normalizer->isInhabited(normTy.get());
 
@@ -576,6 +585,15 @@ TypeFamilyReductionResult<TypeId> unmFamilyFn(TypeId instance, NotNull<TypeFamil
     if (isPending(operandTy, ctx->solver))
         return {std::nullopt, false, {operandTy}, {}};
 
+    // if the type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> maybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, operandTy);
+        if (!maybeGeneralized)
+            return {std::nullopt, false, {operandTy}, {}};
+        operandTy = *maybeGeneralized;
+    }
+
     std::shared_ptr<const NormalizedType> normTy = ctx->normalizer->normalize(operandTy);
 
     // if the operand failed to normalize, we can't reduce, but know nothing about inhabitance.
@@ -674,6 +692,21 @@ TypeFamilyReductionResult<TypeId> numericBinopFamilyFn(TypeId instance, NotNull<
     else if (isPending(rhsTy, ctx->solver))
         return {std::nullopt, false, {rhsTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     // TODO: Normalization needs to remove cyclic type families from a `NormalizedType`.
     std::shared_ptr<const NormalizedType> normLhsTy = ctx->normalizer->normalize(lhsTy);
     std::shared_ptr<const NormalizedType> normRhsTy = ctx->normalizer->normalize(rhsTy);
@@ -895,6 +928,21 @@ TypeFamilyReductionResult<TypeId> concatFamilyFn(TypeId instance, NotNull<TypeFa
     else if (isPending(rhsTy, ctx->solver))
         return {std::nullopt, false, {rhsTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     std::shared_ptr<const NormalizedType> normLhsTy = ctx->normalizer->normalize(lhsTy);
     std::shared_ptr<const NormalizedType> normRhsTy = ctx->normalizer->normalize(rhsTy);
 
@@ -982,13 +1030,27 @@ TypeFamilyReductionResult<TypeId> andFamilyFn(TypeId instance, NotNull<TypeFamil
     if (follow(lhsTy) == instance && lhsTy != rhsTy)
         return {rhsTy, false, {}, {}};
 
-
     // check to see if both operand types are resolved enough, and wait to reduce if not
     if (isPending(lhsTy, ctx->solver))
         return {std::nullopt, false, {lhsTy}, {}};
     else if (isPending(rhsTy, ctx->solver))
         return {std::nullopt, false, {rhsTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     // And evalutes to a boolean if the LHS is falsey, and the RHS type if LHS is truthy.
     SimplifyResult filteredLhs = simplifyIntersection(ctx->builtins, ctx->arena, lhsTy, ctx->builtins->falsyType);
     SimplifyResult overallResult = simplifyUnion(ctx->builtins, ctx->arena, rhsTy, filteredLhs.result);
@@ -1025,6 +1087,21 @@ TypeFamilyReductionResult<TypeId> orFamilyFn(TypeId instance, NotNull<TypeFamily
     else if (isPending(rhsTy, ctx->solver))
         return {std::nullopt, false, {rhsTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     // Or evalutes to the LHS type if the LHS is truthy, and the RHS type if LHS is falsy.
     SimplifyResult filteredLhs = simplifyIntersection(ctx->builtins, ctx->arena, lhsTy, ctx->builtins->truthyType);
     SimplifyResult overallResult = simplifyUnion(ctx->builtins, ctx->arena, rhsTy, filteredLhs.result);
@@ -1088,6 +1165,21 @@ static TypeFamilyReductionResult<TypeId> comparisonFamilyFn(TypeId instance, Not
     lhsTy = follow(lhsTy);
     rhsTy = follow(rhsTy);
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     // check to see if both operand types are resolved enough, and wait to reduce if not
 
     std::shared_ptr<const NormalizedType> normLhsTy = ctx->normalizer->normalize(lhsTy);
@@ -1196,6 +1288,21 @@ TypeFamilyReductionResult<TypeId> eqFamilyFn(TypeId instance, NotNull<TypeFamily
     else if (isPending(rhsTy, ctx->solver))
         return {std::nullopt, false, {rhsTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> lhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, lhsTy);
+        std::optional<TypeId> rhsMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, rhsTy);
+
+        if (!lhsMaybeGeneralized)
+            return {std::nullopt, false, {lhsTy}, {}};
+        else if (!rhsMaybeGeneralized)
+            return {std::nullopt, false, {rhsTy}, {}};
+
+        lhsTy = *lhsMaybeGeneralized;
+        rhsTy = *rhsMaybeGeneralized;
+    }
+
     std::shared_ptr<const NormalizedType> normLhsTy = ctx->normalizer->normalize(lhsTy);
     std::shared_ptr<const NormalizedType> normRhsTy = ctx->normalizer->normalize(rhsTy);
     NormalizationResult lhsInhabited = ctx->normalizer->isInhabited(normLhsTy.get());
@@ -1223,10 +1330,25 @@ TypeFamilyReductionResult<TypeId> eqFamilyFn(TypeId instance, NotNull<TypeFamily
 
     // if neither type has a metatable entry for `__eq`, then we'll check for inhabitance of the intersection!
     NormalizationResult intersectInhabited = ctx->normalizer->isIntersectionInhabited(lhsTy, rhsTy);
-    if (!mmType && intersectInhabited == NormalizationResult::True)
+    if (!mmType)
+    {
+        if (intersectInhabited == NormalizationResult::True)
             return {ctx->builtins->booleanType, false, {}, {}}; // if it's inhabited, everything is okay!
-    else if (!mmType)
+
+        // we might be in a case where we still want to accept the comparison...
+        if (intersectInhabited == NormalizationResult::False)
+        {
+            // if they're both subtypes of `string` but have no common intersection, the comparison is allowed but always `false`.
+            if (normLhsTy->isSubtypeOfString() && normRhsTy->isSubtypeOfString())
+                return {ctx->builtins->falseType, false, {}, {}};
+
+            // if they're both subtypes of `boolean` but have no common intersection, the comparison is allowed but always `false`.
+            if (normLhsTy->isSubtypeOfBooleans() && normRhsTy->isSubtypeOfBooleans())
+                return {ctx->builtins->falseType, false, {}, {}};
+        }
+
         return {std::nullopt, true, {}, {}}; // if it's not, then this family is irreducible!
+    }
 
     mmType = follow(*mmType);
     if (isPending(*mmType, ctx->solver))
@@ -1303,6 +1425,21 @@ TypeFamilyReductionResult<TypeId> refineFamilyFn(TypeId instance, NotNull<TypeFa
     else if (isPending(discriminantTy, ctx->solver))
         return {std::nullopt, false, {discriminantTy}, {}};
 
+    // if either type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> targetMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, targetTy);
+        std::optional<TypeId> discriminantMaybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, discriminantTy);
+
+        if (!targetMaybeGeneralized)
+            return {std::nullopt, false, {targetTy}, {}};
+        else if (!discriminantMaybeGeneralized)
+            return {std::nullopt, false, {discriminantTy}, {}};
+
+        targetTy = *targetMaybeGeneralized;
+        discriminantTy = *discriminantMaybeGeneralized;
+    }
+
     // we need a more complex check for blocking on the discriminant in particular
     FindRefinementBlockers frb;
     frb.traverse(discriminantTy);
@@ -1358,6 +1495,15 @@ TypeFamilyReductionResult<TypeId> singletonFamilyFn(TypeId instance, NotNull<Typ
     if (isPending(type, ctx->solver))
         return {std::nullopt, false, {type}, {}};
 
+    // if the type is free but has only one remaining reference, we can generalize it to its upper bound here.
+    if (ctx->solver)
+    {
+        std::optional<TypeId> maybeGeneralized = ctx->solver->generalizeFreeType(ctx->scope, type);
+        if (!maybeGeneralized)
+            return {std::nullopt, false, {type}, {}};
+        type = *maybeGeneralized;
+    }
+
     TypeId followed = type;
     // we want to follow through a negation here as well.
     if (auto negation = get<NegationType>(followed))

Analysis/src/TypeInfer.cpp

@@ -39,7 +39,6 @@ LUAU_FASTFLAGVARIABLE(LuauAlwaysCommitInferencesOfFunctionCalls, false)
 LUAU_FASTFLAGVARIABLE(LuauRemoveBadRelationalOperatorWarning, false)
 LUAU_FASTFLAGVARIABLE(LuauForbidAliasNamedTypeof, false)
 LUAU_FASTFLAGVARIABLE(LuauOkWithIteratingOverTableProperties, false)
-LUAU_FASTFLAG(LuauFixNormalizeCaching)
 
 namespace Luau
 {
@@ -2649,24 +2648,12 @@ static std::optional<bool> areEqComparable(NotNull<TypeArena> arena, NotNull<Nor
 
     NormalizationResult nr;
 
-    if (FFlag::LuauFixNormalizeCaching)
-    {
     TypeId c = arena->addType(IntersectionType{{a, b}});
     std::shared_ptr<const NormalizedType> n = normalizer->normalize(c);
     if (!n)
         return std::nullopt;
 
     nr = normalizer->isInhabited(n.get());
-    }
-    else
-    {
-        TypeId c = arena->addType(IntersectionType{{a, b}});
-        const NormalizedType* n = normalizer->DEPRECATED_normalize(c);
-        if (!n)
-            return std::nullopt;
-
-        nr = normalizer->isInhabited(n);
-    }
 
     switch (nr)
     {

Analysis/src/Unifier.cpp

@@ -23,7 +23,6 @@ LUAU_FASTFLAG(LuauAlwaysCommitInferencesOfFunctionCalls)
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
 LUAU_FASTFLAGVARIABLE(LuauFixIndexerSubtypingOrdering, false)
 LUAU_FASTFLAGVARIABLE(LuauUnifierShouldNotCopyError, false)
-LUAU_FASTFLAG(LuauFixNormalizeCaching)
 
 namespace Luau
 {
@@ -579,8 +578,6 @@ void Unifier::tryUnify_(TypeId subTy, TypeId superTy, bool isFunctionCall, bool
     if (log.get<AnyType>(subTy))
     {
         if (normalize)
-        {
-            if (FFlag::LuauFixNormalizeCaching)
         {
             // TODO: there are probably cheaper ways to check if any <: T.
             std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
@@ -591,18 +588,6 @@ void Unifier::tryUnify_(TypeId subTy, TypeId superTy, bool isFunctionCall, bool
             if (!log.get<AnyType>(superNorm->tops))
                 failure = true;
         }
-            else
-            {
-                // TODO: there are probably cheaper ways to check if any <: T.
-                const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-
-                if (!superNorm)
-                    return reportError(location, NormalizationTooComplex{});
-
-                if (!log.get<AnyType>(superNorm->tops))
-                    failure = true;
-            }
-        }
         else
             failure = true;
         return tryUnifyWithAny(superTy, builtinTypes->anyType);
@@ -962,8 +947,6 @@ void Unifier::tryUnifyTypeWithUnion(TypeId subTy, TypeId superTy, const UnionTyp
         // We deal with this by type normalization.
         Unifier innerState = makeChildUnifier();
 
-        if (FFlag::LuauFixNormalizeCaching)
-        {
         std::shared_ptr<const NormalizedType> subNorm = normalizer->normalize(subTy);
         std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
         if (!subNorm || !superNorm)
@@ -973,19 +956,6 @@ void Unifier::tryUnifyTypeWithUnion(TypeId subTy, TypeId superTy, const UnionTyp
                 subTy, superTy, *subNorm, *superNorm, "None of the union options are compatible. For example:", *failedOption);
         else
             innerState.tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the union options are compatible");
-        }
-        else
-        {
-            const NormalizedType* subNorm = normalizer->DEPRECATED_normalize(subTy);
-            const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-            if (!subNorm || !superNorm)
-                return reportError(location, NormalizationTooComplex{});
-            else if ((failedOptionCount == 1 || foundHeuristic) && failedOption)
-                innerState.tryUnifyNormalizedTypes(
-                    subTy, superTy, *subNorm, *superNorm, "None of the union options are compatible. For example:", *failedOption);
-            else
-                innerState.tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the union options are compatible");
-        }
 
         if (!innerState.failure)
             log.concat(std::move(innerState.log));
@@ -999,8 +969,6 @@ void Unifier::tryUnifyTypeWithUnion(TypeId subTy, TypeId superTy, const UnionTyp
         // It is possible that T <: A | B even though T </: A and T </:B
         // for example boolean <: true | false.
         // We deal with this by type normalization.
-        if (FFlag::LuauFixNormalizeCaching)
-        {
         std::shared_ptr<const NormalizedType> subNorm = normalizer->normalize(subTy);
         std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
         if (!subNorm || !superNorm)
@@ -1011,19 +979,6 @@ void Unifier::tryUnifyTypeWithUnion(TypeId subTy, TypeId superTy, const UnionTyp
         else
             tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the union options are compatible");
     }
-        else
-        {
-            const NormalizedType* subNorm = normalizer->DEPRECATED_normalize(subTy);
-            const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-            if (!subNorm || !superNorm)
-                reportError(location, NormalizationTooComplex{});
-            else if ((failedOptionCount == 1 || foundHeuristic) && failedOption)
-                tryUnifyNormalizedTypes(
-                    subTy, superTy, *subNorm, *superNorm, "None of the union options are compatible. For example:", *failedOption);
-            else
-                tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the union options are compatible");
-        }
-    }
     else if (!found)
     {
         if (errorsSuppressed)
@@ -1125,24 +1080,12 @@ void Unifier::tryUnifyIntersectionWithType(TypeId subTy, const IntersectionType*
             // It is possible that A & B <: T even though A </: T and B </: T
             // for example (string?) & ~nil <: string.
             // We deal with this by type normalization.
-            if (FFlag::LuauFixNormalizeCaching)
-            {
             std::shared_ptr<const NormalizedType> subNorm = normalizer->normalize(subTy);
             std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
             if (subNorm && superNorm)
                 tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the intersection parts are compatible");
             else
                 reportError(location, NormalizationTooComplex{});
-            }
-            else
-            {
-                const NormalizedType* subNorm = normalizer->DEPRECATED_normalize(subTy);
-                const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-                if (subNorm && superNorm)
-                    tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the intersection parts are compatible");
-                else
-                    reportError(location, NormalizationTooComplex{});
-            }
 
             return;
         }
@@ -1192,8 +1135,6 @@ void Unifier::tryUnifyIntersectionWithType(TypeId subTy, const IntersectionType*
         // for example string? & number? <: nil.
         // We deal with this by type normalization.
 
-        if (FFlag::LuauFixNormalizeCaching)
-        {
         std::shared_ptr<const NormalizedType> subNorm = normalizer->normalize(subTy);
         std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
         if (subNorm && superNorm)
@@ -1201,16 +1142,6 @@ void Unifier::tryUnifyIntersectionWithType(TypeId subTy, const IntersectionType*
         else
             reportError(location, NormalizationTooComplex{});
     }
-        else
-        {
-            const NormalizedType* subNorm = normalizer->DEPRECATED_normalize(subTy);
-            const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-            if (subNorm && superNorm)
-                tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "none of the intersection parts are compatible");
-            else
-                reportError(location, NormalizationTooComplex{});
-        }
-    }
     else if (!found)
     {
         reportError(location, TypeMismatch{superTy, subTy, "none of the intersection parts are compatible", mismatchContext()});
@@ -2712,8 +2643,6 @@ void Unifier::tryUnifyNegations(TypeId subTy, TypeId superTy)
     if (!log.get<NegationType>(subTy) && !log.get<NegationType>(superTy))
         ice("tryUnifyNegations superTy or subTy must be a negation type");
 
-    if (FFlag::LuauFixNormalizeCaching)
-    {
     std::shared_ptr<const NormalizedType> subNorm = normalizer->normalize(subTy);
     std::shared_ptr<const NormalizedType> superNorm = normalizer->normalize(superTy);
     if (!subNorm || !superNorm)
@@ -2725,20 +2654,6 @@ void Unifier::tryUnifyNegations(TypeId subTy, TypeId superTy)
     if (state.errors.empty())
         reportError(location, TypeMismatch{superTy, subTy, mismatchContext()});
 }
-    else
-    {
-        const NormalizedType* subNorm = normalizer->DEPRECATED_normalize(subTy);
-        const NormalizedType* superNorm = normalizer->DEPRECATED_normalize(superTy);
-        if (!subNorm || !superNorm)
-            return reportError(location, NormalizationTooComplex{});
-
-        // T </: ~U iff T <: U
-        Unifier state = makeChildUnifier();
-        state.tryUnifyNormalizedTypes(subTy, superTy, *subNorm, *superNorm, "");
-        if (state.errors.empty())
-            reportError(location, TypeMismatch{superTy, subTy, mismatchContext()});
-    }
-}
 
 static void queueTypePack(std::vector<TypeId>& queue, DenseHashSet<TypePackId>& seenTypePacks, Unifier& state, TypePackId a, TypePackId anyTypePack)
 {

Analysis/src/Unifier2.cpp

@@ -204,25 +204,21 @@ bool Unifier2::unify(TypeId subTy, TypeId superTy)
 
     auto subAny = get<AnyType>(subTy);
     auto superAny = get<AnyType>(superTy);
-    if (subAny && superAny)
-        return true;
-    else if (subAny && superFn)
-    {
-        // If `any` is the subtype, then we can propagate that inward.
-        bool argResult = unify(superFn->argTypes, builtinTypes->anyTypePack);
-        bool retResult = unify(builtinTypes->anyTypePack, superFn->retTypes);
-        return argResult && retResult;
-    }
-    else if (subFn && superAny)
-    {
-        // If `any` is the supertype, then we can propagate that inward.
-        bool argResult = unify(builtinTypes->anyTypePack, subFn->argTypes);
-        bool retResult = unify(subFn->retTypes, builtinTypes->anyTypePack);
-        return argResult && retResult;
-    }
 
     auto subTable = getMutable<TableType>(subTy);
     auto superTable = get<TableType>(superTy);
+
+    if (subAny && superAny)
+        return true;
+    else if (subAny && superFn)
+        return unify(subAny, superFn);
+    else if (subFn && superAny)
+        return unify(subFn, superAny);
+    else if (subAny && superTable)
+        return unify(subAny, superTable);
+    else if (subTable && superAny)
+        return unify(subTable, superAny);
+
     if (subTable && superTable)
     {
         // `boundTo` works like a bound type, and therefore we'd replace it
@@ -451,7 +447,16 @@ bool Unifier2::unify(TableType* subTable, const TableType* superTable)
          * an indexer, we therefore conclude that the unsealed table has the
          * same indexer.
          */
-        subTable->indexer = *superTable->indexer;
+
+        TypeId indexType = superTable->indexer->indexType;
+        if (TypeId* subst = genericSubstitutions.find(indexType))
+            indexType = *subst;
+
+        TypeId indexResultType = superTable->indexer->indexResultType;
+        if (TypeId* subst = genericSubstitutions.find(indexResultType))
+            indexResultType = *subst;
+
+        subTable->indexer = TableIndexer{indexType, indexResultType};
     }
 
     return result;
@@ -462,6 +467,62 @@ bool Unifier2::unify(const MetatableType* subMetatable, const MetatableType* sup
     return unify(subMetatable->metatable, superMetatable->metatable) && unify(subMetatable->table, superMetatable->table);
 }
 
+bool Unifier2::unify(const AnyType* subAny, const FunctionType* superFn)
+{
+    // If `any` is the subtype, then we can propagate that inward.
+    bool argResult = unify(superFn->argTypes, builtinTypes->anyTypePack);
+    bool retResult = unify(builtinTypes->anyTypePack, superFn->retTypes);
+    return argResult && retResult;
+}
+
+bool Unifier2::unify(const FunctionType* subFn, const AnyType* superAny)
+{
+    // If `any` is the supertype, then we can propagate that inward.
+    bool argResult = unify(builtinTypes->anyTypePack, subFn->argTypes);
+    bool retResult = unify(subFn->retTypes, builtinTypes->anyTypePack);
+    return argResult && retResult;
+}
+
+bool Unifier2::unify(const AnyType* subAny, const TableType* superTable)
+{
+    for (const auto& [propName, prop]: superTable->props)
+    {
+        if (prop.readTy)
+            unify(builtinTypes->anyType, *prop.readTy);
+
+        if (prop.writeTy)
+            unify(*prop.writeTy, builtinTypes->anyType);
+    }
+
+    if (superTable->indexer)
+    {
+        unify(builtinTypes->anyType, superTable->indexer->indexType);
+        unify(builtinTypes->anyType, superTable->indexer->indexResultType);
+    }
+
+    return true;
+}
+
+bool Unifier2::unify(const TableType* subTable, const AnyType* superAny)
+{
+    for (const auto& [propName, prop]: subTable->props)
+    {
+        if (prop.readTy)
+            unify(*prop.readTy, builtinTypes->anyType);
+
+        if (prop.writeTy)
+            unify(builtinTypes->anyType, *prop.writeTy);
+    }
+
+    if (subTable->indexer)
+    {
+        unify(subTable->indexer->indexType, builtinTypes->anyType);
+        unify(subTable->indexer->indexResultType, builtinTypes->anyType);
+    }
+
+    return true;
+}
+
 // FIXME?  This should probably return an ErrorVec or an optional<TypeError>
 // rather than a boolean to signal an occurs check failure.
 bool Unifier2::unify(TypePackId subTp, TypePackId superTp)
@@ -596,6 +657,43 @@ struct FreeTypeSearcher : TypeVisitor
         }
     }
 
+    DenseHashSet<const void*> seenPositive{nullptr};
+    DenseHashSet<const void*> seenNegative{nullptr};
+
+    bool seenWithPolarity(const void* ty)
+    {
+        switch (polarity)
+        {
+            case Positive:
+            {
+                if (seenPositive.contains(ty))
+                    return true;
+
+                seenPositive.insert(ty);
+                return false;
+            }
+            case Negative:
+            {
+                if (seenNegative.contains(ty))
+                    return true;
+
+                seenNegative.insert(ty);
+                return false;
+            }
+            case Both:
+            {
+                if (seenPositive.contains(ty) && seenNegative.contains(ty))
+                    return true;
+
+                seenPositive.insert(ty);
+                seenNegative.insert(ty);
+                return false;
+            }
+        }
+
+        return false;
+    }
+
     // The keys in these maps are either TypeIds or TypePackIds. It's safe to
     // mix them because we only use these pointers as unique keys.  We never
     // indirect them.
@@ -604,12 +702,18 @@ struct FreeTypeSearcher : TypeVisitor
 
     bool visit(TypeId ty) override
     {
+        if (seenWithPolarity(ty))
+            return false;
+
         LUAU_ASSERT(ty);
         return true;
     }
 
     bool visit(TypeId ty, const FreeType& ft) override
     {
+        if (seenWithPolarity(ty))
+            return false;
+
         if (!subsumes(scope, ft.scope))
             return true;
 
@@ -632,6 +736,9 @@ struct FreeTypeSearcher : TypeVisitor
 
     bool visit(TypeId ty, const TableType& tt) override
     {
+        if (seenWithPolarity(ty))
+            return false;
+
         if ((tt.state == TableState::Free || tt.state == TableState::Unsealed) && subsumes(scope, tt.scope))
         {
             switch (polarity)
@@ -675,6 +782,9 @@ struct FreeTypeSearcher : TypeVisitor
 
     bool visit(TypeId ty, const FunctionType& ft) override
     {
+        if (seenWithPolarity(ty))
+            return false;
+
         flip();
         traverse(ft.argTypes);
         flip();
@@ -691,6 +801,9 @@ struct FreeTypeSearcher : TypeVisitor
 
     bool visit(TypePackId tp, const FreeTypePack& ftp) override
     {
+        if (seenWithPolarity(tp))
+            return false;
+
         if (!subsumes(scope, ftp.scope))
             return true;
 

Ast/src/Parser.cpp

@@ -17,7 +17,6 @@ LUAU_FASTINTVARIABLE(LuauParseErrorLimit, 100)
 // flag so that we don't break production games by reverting syntax changes.
 // See docs/SyntaxChanges.md for an explanation.
 LUAU_FASTFLAG(LuauCheckedFunctionSyntax)
-LUAU_FASTFLAGVARIABLE(LuauReadWritePropertySyntax, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauDeferredConstraintResolution, false)
 
 namespace Luau
@@ -1340,8 +1339,6 @@ AstType* Parser::parseTableType(bool inDeclarationContext)
         AstTableAccess access = AstTableAccess::ReadWrite;
         std::optional<Location> accessLocation;
 
-        if (FFlag::LuauReadWritePropertySyntax || FFlag::DebugLuauDeferredConstraintResolution)
-        {
         if (lexer.current().type == Lexeme::Name && lexer.lookahead().type != ':')
         {
             if (AstName(lexer.current().name) == "read")
@@ -1357,7 +1354,6 @@ AstType* Parser::parseTableType(bool inDeclarationContext)
                 lexer.next();
             }
         }
-        }
 
         if (lexer.current().type == '[' && (lexer.lookahead().type == Lexeme::RawString || lexer.lookahead().type == Lexeme::QuotedString))
         {

CLI/Repl.cpp

@@ -144,7 +144,10 @@ static int lua_require(lua_State* L)
     if (luau_load(ML, resolvedRequire.chunkName.c_str(), bytecode.data(), bytecode.size(), 0) == 0)
     {
         if (codegen)
-            Luau::CodeGen::compile(ML, -1);
+        {
+            Luau::CodeGen::CompilationOptions nativeOptions;
+            Luau::CodeGen::compile(ML, -1, nativeOptions);
+        }
 
         if (coverageActive())
             coverageTrack(ML, -1);
@@ -602,7 +605,10 @@ static bool runFile(const char* name, lua_State* GL, bool repl)
     if (luau_load(L, chunkname.c_str(), bytecode.data(), bytecode.size(), 0) == 0)
     {
         if (codegen)
-            Luau::CodeGen::compile(L, -1);
+        {
+            Luau::CodeGen::CompilationOptions nativeOptions;
+            Luau::CodeGen::compile(L, -1, nativeOptions);
+        }
 
         if (coverageActive())
             coverageTrack(L, -1);

CodeGen/include/Luau/BytecodeAnalysis.h

@@ -13,10 +13,11 @@ namespace CodeGen
 {
 
 struct IrFunction;
+struct HostIrHooks;
 
 void loadBytecodeTypeInfo(IrFunction& function);
 void buildBytecodeBlocks(IrFunction& function, const std::vector<uint8_t>& jumpTargets);
-void analyzeBytecodeTypes(IrFunction& function);
+void analyzeBytecodeTypes(IrFunction& function, const HostIrHooks& hostHooks);
 
 } // namespace CodeGen
 } // namespace Luau

CodeGen/include/Luau/CodeGen.h

@@ -66,6 +66,39 @@ struct CompilationResult
     }
 };
 
+struct IrBuilder;
+
+using HostVectorOperationBytecodeType = uint8_t (*)(const char* member, size_t memberLength);
+using HostVectorAccessHandler = bool (*)(IrBuilder& builder, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos);
+using HostVectorNamecallHandler = bool (*)(
+    IrBuilder& builder, const char* member, size_t memberLength, int argResReg, int sourceReg, int params, int results, int pcpos);
+
+struct HostIrHooks
+{
+    // Suggest result type of a vector field access
+    HostVectorOperationBytecodeType vectorAccessBytecodeType = nullptr;
+
+    // Suggest result type of a vector function namecall
+    HostVectorOperationBytecodeType vectorNamecallBytecodeType = nullptr;
+
+    // Handle vector value field access
+    // 'sourceReg' is guaranteed to be a vector
+    // Guards should take a VM exit to 'pcpos'
+    HostVectorAccessHandler vectorAccess = nullptr;
+
+    // Handle namecalled performed on a vector value
+    // 'sourceReg' (self argument) is guaranteed to be a vector
+    // All other arguments can be of any type
+    // Guards should take a VM exit to 'pcpos'
+    HostVectorNamecallHandler vectorNamecall = nullptr;
+};
+
+struct CompilationOptions
+{
+    unsigned int flags = 0;
+    HostIrHooks hooks;
+};
+
 struct CompilationStats
 {
     size_t bytecodeSizeBytes = 0;
@@ -118,8 +151,11 @@ void setNativeExecutionEnabled(lua_State* L, bool enabled);
 using ModuleId = std::array<uint8_t, 16>;
 
 // Builds target function and all inner functions
-CompilationResult compile(lua_State* L, int idx, unsigned int flags = 0, CompilationStats* stats = nullptr);
+CompilationResult compile(lua_State* L, int idx, unsigned int flags, CompilationStats* stats = nullptr);
-CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, unsigned int flags = 0, CompilationStats* stats = nullptr);
+CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, unsigned int flags, CompilationStats* stats = nullptr);
+
+CompilationResult compile(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats = nullptr);
+CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats = nullptr);
 
 using AnnotatorFn = void (*)(void* context, std::string& result, int fid, int instpos);
 
@@ -164,7 +200,7 @@ struct AssemblyOptions
 
     Target target = Host;
 
-    unsigned int flags = 0;
+    CompilationOptions compilationOptions;
 
     bool outputBinary = false;
 

CodeGen/include/Luau/IrBuilder.h

@@ -16,11 +16,11 @@ namespace Luau
 namespace CodeGen
 {
 
-struct AssemblyOptions;
+struct HostIrHooks;
 
 struct IrBuilder
 {
-    IrBuilder();
+    IrBuilder(const HostIrHooks& hostHooks);
 
     void buildFunctionIr(Proto* proto);
 
@@ -64,13 +64,17 @@ struct IrBuilder
 
     IrOp vmExit(uint32_t pcpos);
 
+    const HostIrHooks& hostHooks;
+
     bool inTerminatedBlock = false;
 
     bool interruptRequested = false;
 
     bool activeFastcallFallback = false;
     IrOp fastcallFallbackReturn;
-    int fastcallSkipTarget = -1;
+
+    // Force builder to skip source commands
+    int cmdSkipTarget = -1;
 
     IrFunction function;
 

CodeGen/src/BytecodeAnalysis.cpp

@@ -2,6 +2,7 @@
 #include "Luau/BytecodeAnalysis.h"
 
 #include "Luau/BytecodeUtils.h"
+#include "Luau/CodeGen.h"
 #include "Luau/IrData.h"
 #include "Luau/IrUtils.h"
 
@@ -15,6 +16,8 @@ LUAU_FASTFLAG(LuauLoadTypeInfo)                   // Because new VM typeinfo loa
 LUAU_FASTFLAGVARIABLE(LuauCodegenTypeInfo, false) // New analysis is flagged separately
 LUAU_FASTFLAG(LuauTypeInfoLookupImprovement)
 LUAU_FASTFLAGVARIABLE(LuauCodegenVectorMispredictFix, false)
+LUAU_FASTFLAGVARIABLE(LuauCodegenAnalyzeHostVectorOps, false)
+LUAU_FASTFLAGVARIABLE(LuauCodegenLoadTypeUpvalCheck, false)
 
 namespace Luau
 {
@@ -93,7 +96,10 @@ void loadBytecodeTypeInfo(IrFunction& function)
     uint32_t upvalCount = readVarInt(data, offset);
     uint32_t localCount = readVarInt(data, offset);
 
+    if (!FFlag::LuauCodegenLoadTypeUpvalCheck)
+    {
         CODEGEN_ASSERT(upvalCount == unsigned(proto->nups));
+    }
 
     if (typeSize != 0)
     {
@@ -112,6 +118,11 @@ void loadBytecodeTypeInfo(IrFunction& function)
 
     if (upvalCount != 0)
     {
+        if (FFlag::LuauCodegenLoadTypeUpvalCheck)
+        {
+            CODEGEN_ASSERT(upvalCount == unsigned(proto->nups));
+        }
+
         typeInfo.upvalueTypes.resize(upvalCount);
 
         uint8_t* types = (uint8_t*)data + offset;
@@ -609,7 +620,7 @@ void buildBytecodeBlocks(IrFunction& function, const std::vector<uint8_t>& jumpT
     }
 }
 
-void analyzeBytecodeTypes(IrFunction& function)
+void analyzeBytecodeTypes(IrFunction& function, const HostIrHooks& hostHooks)
 {
     Proto* proto = function.proto;
     CODEGEN_ASSERT(proto);
@@ -660,6 +671,8 @@ void analyzeBytecodeTypes(IrFunction& function)
         for (int i = proto->numparams; i < proto->maxstacksize; ++i)
             regTags[i] = LBC_TYPE_ANY;
 
+        LuauBytecodeType knownNextCallResult = LBC_TYPE_ANY;
+
         for (int i = block.startpc; i <= block.finishpc;)
         {
             const Instruction* pc = &proto->code[i];
@@ -788,6 +801,9 @@ void analyzeBytecodeTypes(IrFunction& function)
                             if (ch == 'x' || ch == 'y' || ch == 'z')
                                 regTags[ra] = LBC_TYPE_NUMBER;
                         }
+
+                        if (FFlag::LuauCodegenAnalyzeHostVectorOps && regTags[ra] == LBC_TYPE_ANY && hostHooks.vectorAccessBytecodeType)
+                            regTags[ra] = hostHooks.vectorAccessBytecodeType(field, str->len);
                     }
                 }
                 else
@@ -1159,6 +1175,34 @@ void analyzeBytecodeTypes(IrFunction& function)
                     regTags[ra + 1] = bcType.a;
 
                     bcType.result = LBC_TYPE_FUNCTION;
+
+                    if (FFlag::LuauCodegenAnalyzeHostVectorOps && bcType.a == LBC_TYPE_VECTOR && hostHooks.vectorNamecallBytecodeType)
+                    {
+                        TString* str = gco2ts(function.proto->k[kc].value.gc);
+                        const char* field = getstr(str);
+
+                        knownNextCallResult = LuauBytecodeType(hostHooks.vectorNamecallBytecodeType(field, str->len));
+                    }
+                }
+                break;
+            }
+            case LOP_CALL:
+            {
+                if (FFlag::LuauCodegenAnalyzeHostVectorOps)
+                {
+                    int ra = LUAU_INSN_A(*pc);
+
+                    if (knownNextCallResult != LBC_TYPE_ANY)
+                    {
+                        bcType.result = knownNextCallResult;
+
+                        knownNextCallResult = LBC_TYPE_ANY;
+
+                        regTags[ra] = bcType.result;
+                    }
+
+                    if (FFlag::LuauCodegenTypeInfo)
+                        refineRegType(bcTypeInfo, ra, i, bcType.result);
                 }
                 break;
             }
@@ -1197,7 +1241,6 @@ void analyzeBytecodeTypes(IrFunction& function)
             }
             case LOP_GETGLOBAL:
             case LOP_SETGLOBAL:
-            case LOP_CALL:
             case LOP_RETURN:
             case LOP_JUMP:
             case LOP_JUMPBACK:

CodeGen/src/CodeGen.cpp

@@ -201,12 +201,12 @@ static void logPerfFunction(Proto* p, uintptr_t addr, unsigned size)
 }
 
 template<typename AssemblyBuilder>
-static std::optional<OldNativeProto> createNativeFunction(
+static std::optional<OldNativeProto> createNativeFunction(AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto, uint32_t& totalIrInstCount,
-    AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto, uint32_t& totalIrInstCount, CodeGenCompilationResult& result)
+    const HostIrHooks& hooks, CodeGenCompilationResult& result)
 {
     CODEGEN_ASSERT(!FFlag::LuauCodegenContext);
 
-    IrBuilder ir;
+    IrBuilder ir(hooks);
     ir.buildFunctionIr(proto);
 
     unsigned instCount = unsigned(ir.function.instructions.size());
@@ -476,7 +476,7 @@ void setNativeExecutionEnabled(lua_State* L, bool enabled)
     }
 }
 
-static CompilationResult compile_OLD(lua_State* L, int idx, unsigned int flags, CompilationStats* stats)
+static CompilationResult compile_OLD(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
 {
     CompilationResult compilationResult;
 
@@ -485,7 +485,7 @@ static CompilationResult compile_OLD(lua_State* L, int idx, unsigned int flags,
 
     Proto* root = clvalue(func)->l.p;
 
-    if ((flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
+    if ((options.flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
     {
         compilationResult.result = CodeGenCompilationResult::NotNativeModule;
         return compilationResult;
@@ -500,7 +500,7 @@ static CompilationResult compile_OLD(lua_State* L, int idx, unsigned int flags,
     }
 
     std::vector<Proto*> protos;
-    gatherFunctions(protos, root, flags);
+    gatherFunctions(protos, root, options.flags);
 
     // Skip protos that have been compiled during previous invocations of CodeGen::compile
     protos.erase(std::remove_if(protos.begin(), protos.end(),
@@ -541,7 +541,7 @@ static CompilationResult compile_OLD(lua_State* L, int idx, unsigned int flags,
     {
         CodeGenCompilationResult protoResult = CodeGenCompilationResult::Success;
 
-        if (std::optional<OldNativeProto> np = createNativeFunction(build, helpers, p, totalIrInstCount, protoResult))
+        if (std::optional<OldNativeProto> np = createNativeFunction(build, helpers, p, totalIrInstCount, options.hooks, protoResult))
             results.push_back(*np);
         else
             compilationResult.protoFailures.push_back({protoResult, p->debugname ? getstr(p->debugname) : "", p->linedefined});
@@ -618,13 +618,15 @@ static CompilationResult compile_OLD(lua_State* L, int idx, unsigned int flags,
 
 CompilationResult compile(lua_State* L, int idx, unsigned int flags, CompilationStats* stats)
 {
+    Luau::CodeGen::CompilationOptions options{flags};
+
     if (FFlag::LuauCodegenContext)
     {
-        return compile_NEW(L, idx, flags, stats);
+        return compile_NEW(L, idx, options, stats);
     }
     else
     {
-        return compile_OLD(L, idx, flags, stats);
+        return compile_OLD(L, idx, options, stats);
     }
 }
 
@@ -632,7 +634,27 @@ CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, unsig
 {
     CODEGEN_ASSERT(FFlag::LuauCodegenContext);
 
-    return compile_NEW(moduleId, L, idx, flags, stats);
+    Luau::CodeGen::CompilationOptions options{flags};
+    return compile_NEW(moduleId, L, idx, options, stats);
+}
+
+CompilationResult compile(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
+{
+    if (FFlag::LuauCodegenContext)
+    {
+        return compile_NEW(L, idx, options, stats);
+    }
+    else
+    {
+        return compile_OLD(L, idx, options, stats);
+    }
+}
+
+CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
+{
+    CODEGEN_ASSERT(FFlag::LuauCodegenContext);
+
+    return compile_NEW(moduleId, L, idx, options, stats);
 }
 
 void setPerfLog(void* context, PerfLogFn logFn)

CodeGen/src/CodeGenAssembly.cpp

@@ -183,11 +183,11 @@ static std::string getAssemblyImpl(AssemblyBuilder& build, const TValue* func, A
 {
     Proto* root = clvalue(func)->l.p;
 
-    if ((options.flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
+    if ((options.compilationOptions.flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
         return std::string();
 
     std::vector<Proto*> protos;
-    gatherFunctions(protos, root, options.flags);
+    gatherFunctions(protos, root, options.compilationOptions.flags);
 
     protos.erase(std::remove_if(protos.begin(), protos.end(),
                      [](Proto* p) {
@@ -215,7 +215,7 @@ static std::string getAssemblyImpl(AssemblyBuilder& build, const TValue* func, A
 
     for (Proto* p : protos)
     {
-        IrBuilder ir;
+        IrBuilder ir(options.compilationOptions.hooks);
         ir.buildFunctionIr(p);
         unsigned asmSize = build.getCodeSize();
         unsigned asmCount = build.getInstructionCount();

CodeGen/src/CodeGenContext.cpp

@@ -478,12 +478,12 @@ void create_NEW(lua_State* L, SharedCodeGenContext* codeGenContext)
 }
 
 template<typename AssemblyBuilder>
-[[nodiscard]] static NativeProtoExecDataPtr createNativeFunction(
+[[nodiscard]] static NativeProtoExecDataPtr createNativeFunction(AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto,
-    AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto, uint32_t& totalIrInstCount, CodeGenCompilationResult& result)
+    uint32_t& totalIrInstCount, const HostIrHooks& hooks, CodeGenCompilationResult& result)
 {
     CODEGEN_ASSERT(FFlag::LuauCodegenContext);
 
-    IrBuilder ir;
+    IrBuilder ir(hooks);
     ir.buildFunctionIr(proto);
 
     unsigned instCount = unsigned(ir.function.instructions.size());
@@ -505,7 +505,7 @@ template<typename AssemblyBuilder>
 }
 
 [[nodiscard]] static CompilationResult compileInternal(
-    const std::optional<ModuleId>& moduleId, lua_State* L, int idx, unsigned int flags, CompilationStats* stats)
+    const std::optional<ModuleId>& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
 {
     CODEGEN_ASSERT(FFlag::LuauCodegenContext);
     CODEGEN_ASSERT(lua_isLfunction(L, idx));
@@ -513,7 +513,7 @@ template<typename AssemblyBuilder>
 
     Proto* root = clvalue(func)->l.p;
 
-    if ((flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
+    if ((options.flags & CodeGen_OnlyNativeModules) != 0 && (root->flags & LPF_NATIVE_MODULE) == 0)
         return CompilationResult{CodeGenCompilationResult::NotNativeModule};
 
     BaseCodeGenContext* codeGenContext = getCodeGenContext(L);
@@ -521,7 +521,7 @@ template<typename AssemblyBuilder>
         return CompilationResult{CodeGenCompilationResult::CodeGenNotInitialized};
 
     std::vector<Proto*> protos;
-    gatherFunctions(protos, root, flags);
+    gatherFunctions(protos, root, options.flags);
 
     // Skip protos that have been compiled during previous invocations of CodeGen::compile
     protos.erase(std::remove_if(protos.begin(), protos.end(),
@@ -572,7 +572,7 @@ template<typename AssemblyBuilder>
     {
         CodeGenCompilationResult protoResult = CodeGenCompilationResult::Success;
 
-        NativeProtoExecDataPtr nativeExecData = createNativeFunction(build, helpers, protos[i], totalIrInstCount, protoResult);
+        NativeProtoExecDataPtr nativeExecData = createNativeFunction(build, helpers, protos[i], totalIrInstCount, options.hooks, protoResult);
         if (nativeExecData != nullptr)
         {
             nativeProtos.push_back(std::move(nativeExecData));
@@ -639,18 +639,18 @@ template<typename AssemblyBuilder>
     return compilationResult;
 }
 
-CompilationResult compile_NEW(const ModuleId& moduleId, lua_State* L, int idx, unsigned int flags, CompilationStats* stats)
+CompilationResult compile_NEW(const ModuleId& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
 {
     CODEGEN_ASSERT(FFlag::LuauCodegenContext);
 
-    return compileInternal(moduleId, L, idx, flags, stats);
+    return compileInternal(moduleId, L, idx, options, stats);
 }
 
-CompilationResult compile_NEW(lua_State* L, int idx, unsigned int flags, CompilationStats* stats)
+CompilationResult compile_NEW(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats)
 {
     CODEGEN_ASSERT(FFlag::LuauCodegenContext);
 
-    return compileInternal({}, L, idx, flags, stats);
+    return compileInternal({}, L, idx, options, stats);
 }
 
 [[nodiscard]] bool isNativeExecutionEnabled_NEW(lua_State* L)

CodeGen/src/CodeGenContext.h

@@ -107,8 +107,8 @@ void create_NEW(lua_State* L, size_t blockSize, size_t maxTotalSize, AllocationC
 // destroyed via lua_close.
 void create_NEW(lua_State* L, SharedCodeGenContext* codeGenContext);
 
-CompilationResult compile_NEW(lua_State* L, int idx, unsigned int flags, CompilationStats* stats);
+CompilationResult compile_NEW(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats);
-CompilationResult compile_NEW(const ModuleId& moduleId, lua_State* L, int idx, unsigned int flags, CompilationStats* stats);
+CompilationResult compile_NEW(const ModuleId& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats);
 
 // Returns true if native execution is currently enabled for this VM
 [[nodiscard]] bool isNativeExecutionEnabled_NEW(lua_State* L);

CodeGen/src/IrBuilder.cpp

@@ -15,6 +15,7 @@
 
 LUAU_FASTFLAG(LuauLoadTypeInfo) // Because new VM typeinfo load changes the format used by Codegen, same flag is used
 LUAU_FASTFLAG(LuauTypeInfoLookupImprovement)
+LUAU_FASTFLAG(LuauCodegenAnalyzeHostVectorOps)
 
 namespace Luau
 {
@@ -23,8 +24,9 @@ namespace CodeGen
 
 constexpr unsigned kNoAssociatedBlockIndex = ~0u;
 
-IrBuilder::IrBuilder()
+IrBuilder::IrBuilder(const HostIrHooks& hostHooks)
-    : constantMap({IrConstKind::Tag, ~0ull})
+    : hostHooks(hostHooks)
+    , constantMap({IrConstKind::Tag, ~0ull})
 {
 }
 static bool hasTypedParameters_DEPRECATED(Proto* proto)
@@ -230,7 +232,7 @@ void IrBuilder::buildFunctionIr(Proto* proto)
     rebuildBytecodeBasicBlocks(proto);
 
     // Infer register tags in bytecode
-    analyzeBytecodeTypes(function);
+    analyzeBytecodeTypes(function, hostHooks);
 
     function.bcMapping.resize(proto->sizecode, {~0u, ~0u});
 
@@ -283,10 +285,10 @@ void IrBuilder::buildFunctionIr(Proto* proto)
 
             translateInst(op, pc, i);
 
-            if (fastcallSkipTarget != -1)
+            if (cmdSkipTarget != -1)
             {
-                nexti = fastcallSkipTarget;
+                nexti = cmdSkipTarget;
-                fastcallSkipTarget = -1;
+                cmdSkipTarget = -1;
             }
         }
 
@@ -613,7 +615,15 @@ void IrBuilder::translateInst(LuauOpcode op, const Instruction* pc, int i)
         translateInstCapture(*this, pc, i);
         break;
     case LOP_NAMECALL:
+        if (FFlag::LuauCodegenAnalyzeHostVectorOps)
+        {
+            if (translateInstNamecall(*this, pc, i))
+                cmdSkipTarget = i + 3;
+        }
+        else
+        {
             translateInstNamecall(*this, pc, i);
+        }
         break;
     case LOP_PREPVARARGS:
         inst(IrCmd::FALLBACK_PREPVARARGS, constUint(i), constInt(LUAU_INSN_A(*pc)));
@@ -654,7 +664,7 @@ void IrBuilder::handleFastcallFallback(IrOp fallbackOrUndef, const Instruction*
     }
     else
     {
-        fastcallSkipTarget = i + skip + 2;
+        cmdSkipTarget = i + skip + 2;
     }
 }
 

CodeGen/src/IrTranslation.cpp

@@ -3,6 +3,7 @@
 
 #include "Luau/Bytecode.h"
 #include "Luau/BytecodeUtils.h"
+#include "Luau/CodeGen.h"
 #include "Luau/IrBuilder.h"
 #include "Luau/IrUtils.h"
 
@@ -14,6 +15,7 @@
 
 LUAU_FASTFLAGVARIABLE(LuauCodegenDirectUserdataFlow, false)
 LUAU_FASTFLAGVARIABLE(LuauCodegenFixVectorFields, false)
+LUAU_FASTFLAG(LuauCodegenAnalyzeHostVectorOps)
 
 namespace Luau
 {
@@ -1218,6 +1220,10 @@ void translateInstGetTableKS(IrBuilder& build, const Instruction* pc, int pcpos)
         }
         else
         {
+            if (FFlag::LuauCodegenAnalyzeHostVectorOps && build.hostHooks.vectorAccess &&
+                build.hostHooks.vectorAccess(build, field, str->len, ra, rb, pcpos))
+                return;
+
             build.inst(IrCmd::FALLBACK_GETTABLEKS, build.constUint(pcpos), build.vmReg(ra), build.vmReg(rb), build.vmConst(aux));
         }
 
@@ -1376,7 +1382,7 @@ void translateInstCapture(IrBuilder& build, const Instruction* pc, int pcpos)
     }
 }
 
-void translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos)
+bool translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos)
 {
     int ra = LUAU_INSN_A(*pc);
     int rb = LUAU_INSN_B(*pc);
@@ -1388,8 +1394,24 @@ void translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos)
     {
         build.loadAndCheckTag(build.vmReg(rb), LUA_TVECTOR, build.vmExit(pcpos));
 
+        if (FFlag::LuauCodegenAnalyzeHostVectorOps && build.hostHooks.vectorNamecall)
+        {
+            Instruction call = pc[2];
+            CODEGEN_ASSERT(LUAU_INSN_OP(call) == LOP_CALL);
+
+            int callra = LUAU_INSN_A(call);
+            int nparams = LUAU_INSN_B(call) - 1;
+            int nresults = LUAU_INSN_C(call) - 1;
+
+            TString* str = gco2ts(build.function.proto->k[aux].value.gc);
+            const char* field = getstr(str);
+
+            if (build.hostHooks.vectorNamecall(build, field, str->len, callra, rb, nparams, nresults, pcpos))
+                return true;
+        }
+
         build.inst(IrCmd::FALLBACK_NAMECALL, build.constUint(pcpos), build.vmReg(ra), build.vmReg(rb), build.vmConst(aux));
-        return;
+        return false;
     }
 
     if (FFlag::LuauCodegenDirectUserdataFlow && bcTypes.a == LBC_TYPE_USERDATA)
@@ -1397,7 +1419,7 @@ void translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos)
         build.loadAndCheckTag(build.vmReg(rb), LUA_TUSERDATA, build.vmExit(pcpos));
 
         build.inst(IrCmd::FALLBACK_NAMECALL, build.constUint(pcpos), build.vmReg(ra), build.vmReg(rb), build.vmConst(aux));
-        return;
+        return false;
     }
 
     IrOp next = build.blockAtInst(pcpos + getOpLength(LOP_NAMECALL));
@@ -1451,6 +1473,8 @@ void translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos)
     build.inst(IrCmd::JUMP, next);
 
     build.beginBlock(next);
+
+    return false;
 }
 
 void translateInstAndX(IrBuilder& build, const Instruction* pc, int pcpos, IrOp c)

CodeGen/src/IrTranslation.h

@@ -61,7 +61,7 @@ void translateInstGetGlobal(IrBuilder& build, const Instruction* pc, int pcpos);
 void translateInstSetGlobal(IrBuilder& build, const Instruction* pc, int pcpos);
 void translateInstConcat(IrBuilder& build, const Instruction* pc, int pcpos);
 void translateInstCapture(IrBuilder& build, const Instruction* pc, int pcpos);
-void translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos);
+bool translateInstNamecall(IrBuilder& build, const Instruction* pc, int pcpos);
 void translateInstAndX(IrBuilder& build, const Instruction* pc, int pcpos, IrOp c);
 void translateInstOrX(IrBuilder& build, const Instruction* pc, int pcpos, IrOp c);
 void translateInstNewClosure(IrBuilder& build, const Instruction* pc, int pcpos);

CodeGen/src/lcodegen.cpp

@@ -17,5 +17,6 @@ void luau_codegen_create(lua_State* L)
 
 void luau_codegen_compile(lua_State* L, int idx)
 {
-    Luau::CodeGen::compile(L, idx);
+    Luau::CodeGen::CompilationOptions options;
+    Luau::CodeGen::compile(L, idx, options);
 }

Sources.cmake

@@ -266,7 +266,6 @@ target_sources(Luau.Analysis PRIVATE
     Analysis/src/Refinement.cpp
     Analysis/src/RequireTracer.cpp
     Analysis/src/Scope.cpp
-    Analysis/src/Set.cpp
     Analysis/src/Simplify.cpp
     Analysis/src/Substitution.cpp
     Analysis/src/Subtyping.cpp
@@ -494,6 +493,7 @@ if(TARGET Luau.Conformance)
     target_sources(Luau.Conformance PRIVATE
         tests/RegisterCallbacks.h
         tests/RegisterCallbacks.cpp
+        tests/ConformanceIrHooks.h
         tests/Conformance.test.cpp
         tests/IrLowering.test.cpp
         tests/SharedCodeAllocator.test.cpp

tests/Autocomplete.test.cpp

@@ -3272,9 +3272,9 @@ TEST_CASE_FIXTURE(ACFixture, "string_singleton_in_if_statement")
 // https://github.com/Roblox/luau/issues/858
 TEST_CASE_FIXTURE(ACFixture, "string_singleton_in_if_statement2")
 {
-    ScopedFastFlag sff[]{
+    // don't run this when the DCR flag isn't set
-        {FFlag::DebugLuauDeferredConstraintResolution, true},
+    if (!FFlag::DebugLuauDeferredConstraintResolution)
-    };
+        return;
 
     check(R"(
         --!strict

tests/Conformance.test.cpp

@@ -16,6 +16,7 @@
 
 #include "doctest.h"
 #include "ScopedFlags.h"
+#include "ConformanceIrHooks.h"
 
 #include <fstream>
 #include <string>
@@ -48,6 +49,13 @@ static lua_CompileOptions defaultOptions()
     return copts;
 }
 
+static Luau::CodeGen::CompilationOptions defaultCodegenOptions()
+{
+    Luau::CodeGen::CompilationOptions opts = {};
+    opts.flags = Luau::CodeGen::CodeGen_ColdFunctions;
+    return opts;
+}
+
 static int lua_collectgarbage(lua_State* L)
 {
     static const char* const opts[] = {"stop", "restart", "collect", "count", "isrunning", "step", "setgoal", "setstepmul", "setstepsize", nullptr};
@@ -118,6 +126,15 @@ static int lua_vector_dot(lua_State* L)
     return 1;
 }
 
+static int lua_vector_cross(lua_State* L)
+{
+    const float* a = luaL_checkvector(L, 1);
+    const float* b = luaL_checkvector(L, 2);
+
+    lua_pushvector(L, a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0]);
+    return 1;
+}
+
 static int lua_vector_index(lua_State* L)
 {
     const float* v = luaL_checkvector(L, 1);
@@ -129,6 +146,14 @@ static int lua_vector_index(lua_State* L)
         return 1;
     }
 
+    if (strcmp(name, "Unit") == 0)
+    {
+        float invSqrt = 1.0f / sqrtf(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
+
+        lua_pushvector(L, v[0] * invSqrt, v[1] * invSqrt, v[2] * invSqrt);
+        return 1;
+    }
+
     if (strcmp(name, "Dot") == 0)
     {
         lua_pushcfunction(L, lua_vector_dot, "Dot");
@@ -144,6 +169,9 @@ static int lua_vector_namecall(lua_State* L)
     {
         if (strcmp(str, "Dot") == 0)
             return lua_vector_dot(L);
+
+        if (strcmp(str, "Cross") == 0)
+            return lua_vector_cross(L);
     }
 
     luaL_error(L, "%s is not a valid method of vector", luaL_checkstring(L, 1));
@@ -157,7 +185,8 @@ int lua_silence(lua_State* L)
 using StateRef = std::unique_ptr<lua_State, void (*)(lua_State*)>;
 
 static StateRef runConformance(const char* name, void (*setup)(lua_State* L) = nullptr, void (*yield)(lua_State* L) = nullptr,
-    lua_State* initialLuaState = nullptr, lua_CompileOptions* options = nullptr, bool skipCodegen = false)
+    lua_State* initialLuaState = nullptr, lua_CompileOptions* options = nullptr, bool skipCodegen = false,
+    Luau::CodeGen::CompilationOptions* codegenOptions = nullptr)
 {
 #ifdef LUAU_CONFORMANCE_SOURCE_DIR
     std::string path = LUAU_CONFORMANCE_SOURCE_DIR;
@@ -238,7 +267,11 @@ static StateRef runConformance(const char* name, void (*setup)(lua_State* L) = n
     free(bytecode);
 
     if (result == 0 && codegen && !skipCodegen && luau_codegen_supported())
-        Luau::CodeGen::compile(L, -1, Luau::CodeGen::CodeGen_ColdFunctions);
+    {
+        Luau::CodeGen::CompilationOptions nativeOpts = codegenOptions ? *codegenOptions : defaultCodegenOptions();
+
+        Luau::CodeGen::compile(L, -1, nativeOpts);
+    }
 
     int status = (result == 0) ? lua_resume(L, nullptr, 0) : LUA_ERRSYNTAX;
 
@@ -533,12 +566,51 @@ TEST_CASE("Pack")
 
 TEST_CASE("Vector")
 {
+    lua_CompileOptions copts = defaultOptions();
+    Luau::CodeGen::CompilationOptions nativeOpts = defaultCodegenOptions();
+
+    SUBCASE("NoIrHooks")
+    {
+        SUBCASE("O0")
+        {
+            copts.optimizationLevel = 0;
+        }
+        SUBCASE("O1")
+        {
+            copts.optimizationLevel = 1;
+        }
+        SUBCASE("O2")
+        {
+            copts.optimizationLevel = 2;
+        }
+    }
+    SUBCASE("IrHooks")
+    {
+        nativeOpts.hooks.vectorAccessBytecodeType = vectorAccessBytecodeType;
+        nativeOpts.hooks.vectorNamecallBytecodeType = vectorNamecallBytecodeType;
+        nativeOpts.hooks.vectorAccess = vectorAccess;
+        nativeOpts.hooks.vectorNamecall = vectorNamecall;
+
+        SUBCASE("O0")
+        {
+            copts.optimizationLevel = 0;
+        }
+        SUBCASE("O1")
+        {
+            copts.optimizationLevel = 1;
+        }
+        SUBCASE("O2")
+        {
+            copts.optimizationLevel = 2;
+        }
+    }
+
     runConformance(
         "vector.lua",
         [](lua_State* L) {
             setupVectorHelpers(L);
         },
-        nullptr, nullptr, nullptr);
+        nullptr, nullptr, &copts, false, &nativeOpts);
 }
 
 static void populateRTTI(lua_State* L, Luau::TypeId type)
@@ -2141,7 +2213,10 @@ TEST_CASE("HugeFunction")
     REQUIRE(result == 0);
 
     if (codegen && luau_codegen_supported())
-        Luau::CodeGen::compile(L, -1, Luau::CodeGen::CodeGen_ColdFunctions);
+    {
+        Luau::CodeGen::CompilationOptions nativeOptions{Luau::CodeGen::CodeGen_ColdFunctions};
+        Luau::CodeGen::compile(L, -1, nativeOptions);
+    }
 
     int status = lua_resume(L, nullptr, 0);
     REQUIRE(status == 0);
@@ -2263,8 +2338,9 @@ TEST_CASE("IrInstructionLimit")
 
     REQUIRE(result == 0);
 
+    Luau::CodeGen::CompilationOptions nativeOptions{Luau::CodeGen::CodeGen_ColdFunctions};
     Luau::CodeGen::CompilationStats nativeStats = {};
-    Luau::CodeGen::CompilationResult nativeResult = Luau::CodeGen::compile(L, -1, Luau::CodeGen::CodeGen_ColdFunctions, &nativeStats);
+    Luau::CodeGen::CompilationResult nativeResult = Luau::CodeGen::compile(L, -1, nativeOptions, &nativeStats);
 
     // Limit is not hit immediately, so with some functions compiled it should be a success
     CHECK(nativeResult.result == Luau::CodeGen::CodeGenCompilationResult::Success);

tests/ConformanceIrHooks.h

@@ -0,0 +1,151 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/IrBuilder.h"
+
+inline uint8_t vectorAccessBytecodeType(const char* member, size_t memberLength)
+{
+    using namespace Luau::CodeGen;
+
+    if (memberLength == strlen("Magnitude") && strcmp(member, "Magnitude") == 0)
+        return LBC_TYPE_NUMBER;
+
+    if (memberLength == strlen("Unit") && strcmp(member, "Unit") == 0)
+        return LBC_TYPE_VECTOR;
+
+    return LBC_TYPE_ANY;
+}
+
+inline bool vectorAccess(Luau::CodeGen::IrBuilder& build, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos)
+{
+    using namespace Luau::CodeGen;
+
+    if (memberLength == strlen("Magnitude") && strcmp(member, "Magnitude") == 0)
+    {
+        IrOp x = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(0));
+        IrOp y = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(4));
+        IrOp z = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(8));
+
+        IrOp x2 = build.inst(IrCmd::MUL_NUM, x, x);
+        IrOp y2 = build.inst(IrCmd::MUL_NUM, y, y);
+        IrOp z2 = build.inst(IrCmd::MUL_NUM, z, z);
+
+        IrOp sum = build.inst(IrCmd::ADD_NUM, build.inst(IrCmd::ADD_NUM, x2, y2), z2);
+
+        IrOp mag = build.inst(IrCmd::SQRT_NUM, sum);
+
+        build.inst(IrCmd::STORE_DOUBLE, build.vmReg(resultReg), mag);
+        build.inst(IrCmd::STORE_TAG, build.vmReg(resultReg), build.constTag(LUA_TNUMBER));
+
+        return true;
+    }
+
+    if (memberLength == strlen("Unit") && strcmp(member, "Unit") == 0)
+    {
+        IrOp x = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(0));
+        IrOp y = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(4));
+        IrOp z = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(8));
+
+        IrOp x2 = build.inst(IrCmd::MUL_NUM, x, x);
+        IrOp y2 = build.inst(IrCmd::MUL_NUM, y, y);
+        IrOp z2 = build.inst(IrCmd::MUL_NUM, z, z);
+
+        IrOp sum = build.inst(IrCmd::ADD_NUM, build.inst(IrCmd::ADD_NUM, x2, y2), z2);
+
+        IrOp mag = build.inst(IrCmd::SQRT_NUM, sum);
+        IrOp inv = build.inst(IrCmd::DIV_NUM, build.constDouble(1.0), mag);
+
+        IrOp xr = build.inst(IrCmd::MUL_NUM, x, inv);
+        IrOp yr = build.inst(IrCmd::MUL_NUM, y, inv);
+        IrOp zr = build.inst(IrCmd::MUL_NUM, z, inv);
+
+        build.inst(IrCmd::STORE_VECTOR, build.vmReg(resultReg), xr, yr, zr);
+        build.inst(IrCmd::STORE_TAG, build.vmReg(resultReg), build.constTag(LUA_TVECTOR));
+
+        return true;
+    }
+
+    return false;
+}
+
+inline uint8_t vectorNamecallBytecodeType(const char* member, size_t memberLength)
+{
+    if (memberLength == strlen("Dot") && strcmp(member, "Dot") == 0)
+        return LBC_TYPE_NUMBER;
+
+    if (memberLength == strlen("Cross") && strcmp(member, "Cross") == 0)
+        return LBC_TYPE_VECTOR;
+
+    return LBC_TYPE_ANY;
+}
+
+inline bool vectorNamecall(
+    Luau::CodeGen::IrBuilder& build, const char* member, size_t memberLength, int argResReg, int sourceReg, int params, int results, int pcpos)
+{
+    using namespace Luau::CodeGen;
+
+    if (memberLength == strlen("Dot") && strcmp(member, "Dot") == 0 && params == 2 && results <= 1)
+    {
+        build.loadAndCheckTag(build.vmReg(argResReg + 2), LUA_TVECTOR, build.vmExit(pcpos));
+
+        IrOp x1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(0));
+        IrOp x2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(0));
+        IrOp xx = build.inst(IrCmd::MUL_NUM, x1, x2);
+
+        IrOp y1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(4));
+        IrOp y2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(4));
+        IrOp yy = build.inst(IrCmd::MUL_NUM, y1, y2);
+
+        IrOp z1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(8));
+        IrOp z2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(8));
+        IrOp zz = build.inst(IrCmd::MUL_NUM, z1, z2);
+
+        IrOp sum = build.inst(IrCmd::ADD_NUM, build.inst(IrCmd::ADD_NUM, xx, yy), zz);
+
+        build.inst(IrCmd::STORE_DOUBLE, build.vmReg(argResReg), sum);
+        build.inst(IrCmd::STORE_TAG, build.vmReg(argResReg), build.constTag(LUA_TNUMBER));
+
+        // If the function is called in multi-return context, stack has to be adjusted
+        if (results == LUA_MULTRET)
+            build.inst(IrCmd::ADJUST_STACK_TO_REG, build.vmReg(argResReg), build.constInt(1));
+
+        return true;
+    }
+
+    if (memberLength == strlen("Cross") && strcmp(member, "Cross") == 0 && params == 2 && results <= 1)
+    {
+        build.loadAndCheckTag(build.vmReg(argResReg + 2), LUA_TVECTOR, build.vmExit(pcpos));
+
+        IrOp x1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(0));
+        IrOp x2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(0));
+
+        IrOp y1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(4));
+        IrOp y2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(4));
+
+        IrOp z1 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(sourceReg), build.constInt(8));
+        IrOp z2 = build.inst(IrCmd::LOAD_FLOAT, build.vmReg(argResReg + 2), build.constInt(8));
+
+        IrOp y1z2 = build.inst(IrCmd::MUL_NUM, y1, z2);
+        IrOp z1y2 = build.inst(IrCmd::MUL_NUM, z1, y2);
+        IrOp xr = build.inst(IrCmd::SUB_NUM, y1z2, z1y2);
+
+        IrOp z1x2 = build.inst(IrCmd::MUL_NUM, z1, x2);
+        IrOp x1z2 = build.inst(IrCmd::MUL_NUM, x1, z2);
+        IrOp yr = build.inst(IrCmd::SUB_NUM, z1x2, x1z2);
+
+        IrOp x1y2 = build.inst(IrCmd::MUL_NUM, x1, y2);
+        IrOp y1x2 = build.inst(IrCmd::MUL_NUM, y1, x2);
+        IrOp zr = build.inst(IrCmd::SUB_NUM, x1y2, y1x2);
+
+        build.inst(IrCmd::STORE_VECTOR, build.vmReg(argResReg), xr, yr, zr);
+        build.inst(IrCmd::STORE_TAG, build.vmReg(argResReg), build.constTag(LUA_TVECTOR));
+
+        // If the function is called in multi-return context, stack has to be adjusted
+        if (results == LUA_MULTRET)
+            build.inst(IrCmd::ADJUST_STACK_TO_REG, build.vmReg(argResReg), build.constInt(1));
+
+        return true;
+    }
+
+    return false;
+}

tests/IrBuilder.test.cpp

@@ -21,6 +21,11 @@ using namespace Luau::CodeGen;
 class IrBuilderFixture
 {
 public:
+    IrBuilderFixture()
+        : build(hooks)
+    {
+    }
+
     void constantFold()
     {
         for (IrBlock& block : build.function.blocks)
@@ -109,6 +114,7 @@ public:
         computeCfgDominanceTreeChildren(build.function);
     }
 
+    HostIrHooks hooks;
     IrBuilder build;
 
     // Luau.VM headers are not accessible

tests/IrLowering.test.cpp

@@ -6,9 +6,11 @@
 #include "Luau/CodeGen.h"
 #include "Luau/Compiler.h"
 #include "Luau/Parser.h"
+#include "Luau/IrBuilder.h"
 
 #include "doctest.h"
 #include "ScopedFlags.h"
+#include "ConformanceIrHooks.h"
 
 #include <memory>
 
@@ -22,11 +24,17 @@ LUAU_FASTFLAG(LuauCodegenIrTypeNames)
 LUAU_FASTFLAG(LuauCompileTempTypeInfo)
 LUAU_FASTFLAG(LuauCodegenFixVectorFields)
 LUAU_FASTFLAG(LuauCodegenVectorMispredictFix)
+LUAU_FASTFLAG(LuauCodegenAnalyzeHostVectorOps)
 
 static std::string getCodegenAssembly(const char* source, bool includeIrTypes = false, int debugLevel = 1)
 {
     Luau::CodeGen::AssemblyOptions options;
 
+    options.compilationOptions.hooks.vectorAccessBytecodeType = vectorAccessBytecodeType;
+    options.compilationOptions.hooks.vectorNamecallBytecodeType = vectorNamecallBytecodeType;
+    options.compilationOptions.hooks.vectorAccess = vectorAccess;
+    options.compilationOptions.hooks.vectorNamecall = vectorNamecall;
+
     // For IR, we don't care about assembly, but we want a stable target
     options.target = Luau::CodeGen::AssemblyOptions::Target::X64_SystemV;
 
@@ -513,6 +521,277 @@ bb_6:
 )");
 }
 
+TEST_CASE("VectorCustomAccess")
+{
+    ScopedFastFlag luauCodegenRemoveDeadStores{FFlag::LuauCodegenRemoveDeadStores5, true};
+    ScopedFastFlag luauCodegenVectorMispredictFix{FFlag::LuauCodegenVectorMispredictFix, true};
+    ScopedFastFlag luauCodegenAnalyzeHostVectorOps{FFlag::LuauCodegenAnalyzeHostVectorOps, true};
+
+    CHECK_EQ("\n" + getCodegenAssembly(R"(
+local function vec3magn(a: vector)
+    return a.Magnitude * 2
+end
+)"),
+        R"(
+; function vec3magn($arg0) line 2
+bb_0:
+  CHECK_TAG R0, tvector, exit(entry)
+  JUMP bb_2
+bb_2:
+  JUMP bb_bytecode_1
+bb_bytecode_1:
+  %6 = LOAD_FLOAT R0, 0i
+  %7 = LOAD_FLOAT R0, 4i
+  %8 = LOAD_FLOAT R0, 8i
+  %9 = MUL_NUM %6, %6
+  %10 = MUL_NUM %7, %7
+  %11 = MUL_NUM %8, %8
+  %12 = ADD_NUM %9, %10
+  %13 = ADD_NUM %12, %11
+  %14 = SQRT_NUM %13
+  %20 = MUL_NUM %14, 2
+  STORE_DOUBLE R1, %20
+  STORE_TAG R1, tnumber
+  INTERRUPT 3u
+  RETURN R1, 1i
+)");
+}
+
+TEST_CASE("VectorCustomNamecall")
+{
+    ScopedFastFlag luauCodegenRemoveDeadStores{FFlag::LuauCodegenRemoveDeadStores5, true};
+    ScopedFastFlag LuauCodegenDirectUserdataFlow{FFlag::LuauCodegenDirectUserdataFlow, true};
+    ScopedFastFlag luauCodegenAnalyzeHostVectorOps{FFlag::LuauCodegenAnalyzeHostVectorOps, true};
+
+    CHECK_EQ("\n" + getCodegenAssembly(R"(
+local function vec3dot(a: vector, b: vector)
+    return (a:Dot(b))
+end
+)"),
+        R"(
+; function vec3dot($arg0, $arg1) line 2
+bb_0:
+  CHECK_TAG R0, tvector, exit(entry)
+  CHECK_TAG R1, tvector, exit(entry)
+  JUMP bb_2
+bb_2:
+  JUMP bb_bytecode_1
+bb_bytecode_1:
+  %6 = LOAD_TVALUE R1
+  STORE_TVALUE R4, %6
+  %12 = LOAD_FLOAT R0, 0i
+  %13 = LOAD_FLOAT R4, 0i
+  %14 = MUL_NUM %12, %13
+  %15 = LOAD_FLOAT R0, 4i
+  %16 = LOAD_FLOAT R4, 4i
+  %17 = MUL_NUM %15, %16
+  %18 = LOAD_FLOAT R0, 8i
+  %19 = LOAD_FLOAT R4, 8i
+  %20 = MUL_NUM %18, %19
+  %21 = ADD_NUM %14, %17
+  %22 = ADD_NUM %21, %20
+  STORE_DOUBLE R2, %22
+  STORE_TAG R2, tnumber
+  INTERRUPT 4u
+  RETURN R2, 1i
+)");
+}
+
+TEST_CASE("VectorCustomAccessChain")
+{
+    ScopedFastFlag luauCodegenRemoveDeadStores{FFlag::LuauCodegenRemoveDeadStores5, true};
+    ScopedFastFlag luauCodegenVectorMispredictFix{FFlag::LuauCodegenVectorMispredictFix, true};
+    ScopedFastFlag LuauCodegenDirectUserdataFlow{FFlag::LuauCodegenDirectUserdataFlow, true};
+    ScopedFastFlag luauCodegenAnalyzeHostVectorOps{FFlag::LuauCodegenAnalyzeHostVectorOps, true};
+
+    CHECK_EQ("\n" + getCodegenAssembly(R"(
+local function foo(a: vector, b: vector)
+    return a.Unit * b.Magnitude
+end
+)"),
+        R"(
+; function foo($arg0, $arg1) line 2
+bb_0:
+  CHECK_TAG R0, tvector, exit(entry)
+  CHECK_TAG R1, tvector, exit(entry)
+  JUMP bb_2
+bb_2:
+  JUMP bb_bytecode_1
+bb_bytecode_1:
+  %8 = LOAD_FLOAT R0, 0i
+  %9 = LOAD_FLOAT R0, 4i
+  %10 = LOAD_FLOAT R0, 8i
+  %11 = MUL_NUM %8, %8
+  %12 = MUL_NUM %9, %9
+  %13 = MUL_NUM %10, %10
+  %14 = ADD_NUM %11, %12
+  %15 = ADD_NUM %14, %13
+  %16 = SQRT_NUM %15
+  %17 = DIV_NUM 1, %16
+  %18 = MUL_NUM %8, %17
+  %19 = MUL_NUM %9, %17
+  %20 = MUL_NUM %10, %17
+  STORE_VECTOR R3, %18, %19, %20
+  STORE_TAG R3, tvector
+  %25 = LOAD_FLOAT R1, 0i
+  %26 = LOAD_FLOAT R1, 4i
+  %27 = LOAD_FLOAT R1, 8i
+  %28 = MUL_NUM %25, %25
+  %29 = MUL_NUM %26, %26
+  %30 = MUL_NUM %27, %27
+  %31 = ADD_NUM %28, %29
+  %32 = ADD_NUM %31, %30
+  %33 = SQRT_NUM %32
+  %40 = LOAD_TVALUE R3
+  %42 = NUM_TO_VEC %33
+  %43 = MUL_VEC %40, %42
+  %44 = TAG_VECTOR %43
+  STORE_TVALUE R2, %44
+  INTERRUPT 5u
+  RETURN R2, 1i
+)");
+}
+
+TEST_CASE("VectorCustomNamecallChain")
+{
+    ScopedFastFlag luauCodegenRemoveDeadStores{FFlag::LuauCodegenRemoveDeadStores5, true};
+    ScopedFastFlag luauCodegenVectorMispredictFix{FFlag::LuauCodegenVectorMispredictFix, true};
+    ScopedFastFlag LuauCodegenDirectUserdataFlow{FFlag::LuauCodegenDirectUserdataFlow, true};
+    ScopedFastFlag luauCodegenAnalyzeHostVectorOps{FFlag::LuauCodegenAnalyzeHostVectorOps, true};
+
+    CHECK_EQ("\n" + getCodegenAssembly(R"(
+local function foo(n: vector, b: vector, t: vector)
+    return n:Cross(t):Dot(b) + 1
+end
+)"),
+        R"(
+; function foo($arg0, $arg1, $arg2) line 2
+bb_0:
+  CHECK_TAG R0, tvector, exit(entry)
+  CHECK_TAG R1, tvector, exit(entry)
+  CHECK_TAG R2, tvector, exit(entry)
+  JUMP bb_2
+bb_2:
+  JUMP bb_bytecode_1
+bb_bytecode_1:
+  %8 = LOAD_TVALUE R2
+  STORE_TVALUE R6, %8
+  %14 = LOAD_FLOAT R0, 0i
+  %15 = LOAD_FLOAT R6, 0i
+  %16 = LOAD_FLOAT R0, 4i
+  %17 = LOAD_FLOAT R6, 4i
+  %18 = LOAD_FLOAT R0, 8i
+  %19 = LOAD_FLOAT R6, 8i
+  %20 = MUL_NUM %16, %19
+  %21 = MUL_NUM %18, %17
+  %22 = SUB_NUM %20, %21
+  %23 = MUL_NUM %18, %15
+  %24 = MUL_NUM %14, %19
+  %25 = SUB_NUM %23, %24
+  %26 = MUL_NUM %14, %17
+  %27 = MUL_NUM %16, %15
+  %28 = SUB_NUM %26, %27
+  STORE_VECTOR R4, %22, %25, %28
+  STORE_TAG R4, tvector
+  %31 = LOAD_TVALUE R1
+  STORE_TVALUE R6, %31
+  %37 = LOAD_FLOAT R4, 0i
+  %38 = LOAD_FLOAT R6, 0i
+  %39 = MUL_NUM %37, %38
+  %40 = LOAD_FLOAT R4, 4i
+  %41 = LOAD_FLOAT R6, 4i
+  %42 = MUL_NUM %40, %41
+  %43 = LOAD_FLOAT R4, 8i
+  %44 = LOAD_FLOAT R6, 8i
+  %45 = MUL_NUM %43, %44
+  %46 = ADD_NUM %39, %42
+  %47 = ADD_NUM %46, %45
+  %53 = ADD_NUM %47, 1
+  STORE_DOUBLE R3, %53
+  STORE_TAG R3, tnumber
+  INTERRUPT 9u
+  RETURN R3, 1i
+)");
+}
+
+TEST_CASE("VectorCustomNamecallChain2")
+{
+    ScopedFastFlag sffs[]{{FFlag::LuauLoadTypeInfo, true}, {FFlag::LuauCompileTypeInfo, true}, {FFlag::LuauCodegenTypeInfo, true},
+        {FFlag::LuauCodegenRemoveDeadStores5, true}, {FFlag::LuauTypeInfoLookupImprovement, true}, {FFlag::LuauCompileTempTypeInfo, true},
+        {FFlag::LuauCodegenVectorMispredictFix, true}, {FFlag::LuauCodegenDirectUserdataFlow, true}, {FFlag::LuauCodegenAnalyzeHostVectorOps, true}};
+
+    CHECK_EQ("\n" + getCodegenAssembly(R"(
+type Vertex = {n: vector, b: vector}
+
+local function foo(v: Vertex, t: vector)
+    return v.n:Cross(t):Dot(v.b) + 1
+end
+)"),
+        R"(
+; function foo($arg0, $arg1) line 4
+bb_0:
+  CHECK_TAG R0, ttable, exit(entry)
+  CHECK_TAG R1, tvector, exit(entry)
+  JUMP bb_2
+bb_2:
+  JUMP bb_bytecode_1
+bb_bytecode_1:
+  %8 = LOAD_POINTER R0
+  %9 = GET_SLOT_NODE_ADDR %8, 0u, K1
+  CHECK_SLOT_MATCH %9, K1, bb_fallback_3
+  %11 = LOAD_TVALUE %9, 0i
+  STORE_TVALUE R3, %11
+  JUMP bb_4
+bb_4:
+  %16 = LOAD_TVALUE R1
+  STORE_TVALUE R5, %16
+  CHECK_TAG R3, tvector, exit(3)
+  CHECK_TAG R5, tvector, exit(3)
+  %22 = LOAD_FLOAT R3, 0i
+  %23 = LOAD_FLOAT R5, 0i
+  %24 = LOAD_FLOAT R3, 4i
+  %25 = LOAD_FLOAT R5, 4i
+  %26 = LOAD_FLOAT R3, 8i
+  %27 = LOAD_FLOAT R5, 8i
+  %28 = MUL_NUM %24, %27
+  %29 = MUL_NUM %26, %25
+  %30 = SUB_NUM %28, %29
+  %31 = MUL_NUM %26, %23
+  %32 = MUL_NUM %22, %27
+  %33 = SUB_NUM %31, %32
+  %34 = MUL_NUM %22, %25
+  %35 = MUL_NUM %24, %23
+  %36 = SUB_NUM %34, %35
+  STORE_VECTOR R3, %30, %33, %36
+  CHECK_TAG R0, ttable, exit(6)
+  %41 = LOAD_POINTER R0
+  %42 = GET_SLOT_NODE_ADDR %41, 6u, K3
+  CHECK_SLOT_MATCH %42, K3, bb_fallback_5
+  %44 = LOAD_TVALUE %42, 0i
+  STORE_TVALUE R5, %44
+  JUMP bb_6
+bb_6:
+  CHECK_TAG R3, tvector, exit(8)
+  CHECK_TAG R5, tvector, exit(8)
+  %53 = LOAD_FLOAT R3, 0i
+  %54 = LOAD_FLOAT R5, 0i
+  %55 = MUL_NUM %53, %54
+  %56 = LOAD_FLOAT R3, 4i
+  %57 = LOAD_FLOAT R5, 4i
+  %58 = MUL_NUM %56, %57
+  %59 = LOAD_FLOAT R3, 8i
+  %60 = LOAD_FLOAT R5, 8i
+  %61 = MUL_NUM %59, %60
+  %62 = ADD_NUM %55, %58
+  %63 = ADD_NUM %62, %61
+  %69 = ADD_NUM %63, 1
+  STORE_DOUBLE R2, %69
+  STORE_TAG R2, tnumber
+  INTERRUPT 12u
+  RETURN R2, 1i
+)");
+}
+
 TEST_CASE("UserDataGetIndex")
 {
     ScopedFastFlag luauCodegenDirectUserdataFlow{FFlag::LuauCodegenDirectUserdataFlow, true};
@@ -1040,7 +1319,7 @@ TEST_CASE("ResolveVectorNamecalls")
 {
     ScopedFastFlag sffs[]{{FFlag::LuauLoadTypeInfo, true}, {FFlag::LuauCompileTypeInfo, true}, {FFlag::LuauCodegenTypeInfo, true},
         {FFlag::LuauCodegenRemoveDeadStores5, true}, {FFlag::LuauTypeInfoLookupImprovement, true}, {FFlag::LuauCodegenIrTypeNames, true},
-        {FFlag::LuauCompileTempTypeInfo, true}, {FFlag::LuauCodegenDirectUserdataFlow, true}};
+        {FFlag::LuauCompileTempTypeInfo, true}, {FFlag::LuauCodegenDirectUserdataFlow, true}, {FFlag::LuauCodegenAnalyzeHostVectorOps, true}};
 
     CHECK_EQ("\n" + getCodegenAssembly(R"(
 type Vertex = {pos: vector, normal: vector}
@@ -1083,10 +1362,20 @@ bb_6:
   %31 = LOAD_TVALUE K1, 0i, tvector
   STORE_TVALUE R4, %31
   CHECK_TAG R2, tvector, exit(4)
-  FALLBACK_NAMECALL 4u, R2, R2, K2
+  %37 = LOAD_FLOAT R2, 0i
-  INTERRUPT 6u
+  %38 = LOAD_FLOAT R4, 0i
-  SET_SAVEDPC 7u
+  %39 = MUL_NUM %37, %38
-  CALL R2, 2i, -1i
+  %40 = LOAD_FLOAT R2, 4i
+  %41 = LOAD_FLOAT R4, 4i
+  %42 = MUL_NUM %40, %41
+  %43 = LOAD_FLOAT R2, 8i
+  %44 = LOAD_FLOAT R4, 8i
+  %45 = MUL_NUM %43, %44
+  %46 = ADD_NUM %39, %42
+  %47 = ADD_NUM %46, %45
+  STORE_DOUBLE R2, %47
+  STORE_TAG R2, tnumber
+  ADJUST_STACK_TO_REG R2, 1i
   INTERRUPT 7u
   RETURN R2, -1i
 )");

tests/Normalize.test.cpp

@@ -11,7 +11,6 @@
 #include "Luau/BuiltinDefinitions.h"
 
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
-LUAU_FASTFLAG(LuauFixNormalizeCaching)
 LUAU_FASTFLAG(LuauNormalizeNotUnknownIntersection)
 LUAU_FASTFLAG(LuauFixCyclicUnionsOfIntersections);
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
@@ -428,7 +427,6 @@ struct NormalizeFixture : Fixture
     UnifierSharedState unifierState{&iceHandler};
     Normalizer normalizer{&arena, builtinTypes, NotNull{&unifierState}};
     Scope globalScope{builtinTypes->anyTypePack};
-    ScopedFastFlag fixNormalizeCaching{FFlag::LuauFixNormalizeCaching, true};
 
     NormalizeFixture()
     {

tests/Parser.test.cpp

@@ -17,7 +17,6 @@ LUAU_FASTINT(LuauRecursionLimit);
 LUAU_FASTINT(LuauTypeLengthLimit);
 LUAU_FASTINT(LuauParseErrorLimit);
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
-LUAU_FASTFLAG(LuauReadWritePropertySyntax);
 
 namespace
 {
@@ -3156,8 +3155,6 @@ TEST_CASE_FIXTURE(Fixture, "cannot_use_@_as_variable_name")
 
 TEST_CASE_FIXTURE(Fixture, "read_write_table_properties")
 {
-    ScopedFastFlag sff{FFlag::LuauReadWritePropertySyntax, true};
-
     auto pr = tryParse(R"(
         type A = {read x: number}
         type B = {write x: number}

tests/Set.test.cpp

@@ -7,8 +7,6 @@
 #include <string>
 #include <vector>
 
-LUAU_FASTFLAG(LuauFixSetIter);
-
 TEST_SUITE_BEGIN("SetTests");
 
 TEST_CASE("empty_set_size_0")
@@ -107,8 +105,6 @@ TEST_CASE("iterate_over_set_skips_erased_elements")
 
 TEST_CASE("iterate_over_set_skips_first_element_if_it_is_erased")
 {
-    ScopedFastFlag sff{FFlag::LuauFixSetIter, true};
-
     /*
      * As of this writing, in the following set, the key "y" happens to occur
      * before "x" in the underlying DenseHashSet.  This is important because it

tests/SharedCodeAllocator.test.cpp

@@ -438,10 +438,13 @@ TEST_CASE("SharedAllocation")
 
     const ModuleId moduleId = {0x01};
 
+    CompilationOptions options;
+    options.flags = CodeGen_ColdFunctions;
+
     CompilationStats nativeStats1 = {};
     CompilationStats nativeStats2 = {};
-    const CompilationResult codeGenResult1 = Luau::CodeGen::compile(moduleId, L1.get(), -1, CodeGen_ColdFunctions, &nativeStats1);
+    const CompilationResult codeGenResult1 = Luau::CodeGen::compile(moduleId, L1.get(), -1, options, &nativeStats1);
-    const CompilationResult codeGenResult2 = Luau::CodeGen::compile(moduleId, L2.get(), -1, CodeGen_ColdFunctions, &nativeStats2);
+    const CompilationResult codeGenResult2 = Luau::CodeGen::compile(moduleId, L2.get(), -1, options, &nativeStats2);
     REQUIRE(codeGenResult1.result == CodeGenCompilationResult::Success);
     REQUIRE(codeGenResult2.result == CodeGenCompilationResult::Success);
 

tests/ToString.test.cpp

@@ -354,21 +354,41 @@ 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)
+    {
+        LUAU_REQUIRE_ERROR_COUNT(3, result);
+        auto err = get<ExplicitFunctionAnnotationRecommended>(result.errors[0]);
+        LUAU_ASSERT(err);
+        CHECK("(...any) -> ()" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+        err = get<ExplicitFunctionAnnotationRecommended>(result.errors[1]);
+        LUAU_ASSERT(err);
+        // FIXME: this recommendation could be better
+        CHECK("<a>(a) -> or<a, (...any) -> ()>" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+        err = get<ExplicitFunctionAnnotationRecommended>(result.errors[2]);
+        LUAU_ASSERT(err);
+        // FIXME: this recommendation could be better
+        CHECK("<a>(a) -> or<a, <b>(b) -> or<b, (...any) -> ()>>" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+
+        ToStringOptions o;
+        o.exhaustive = false;
+        o.maxTypeLength = 20;
+        CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
+        CHECK_EQ(toString(requireType("f1"), o), "<a>(a) -> or<a, () -> ... *TRUNCATED*");
+        CHECK_EQ(toString(requireType("f2"), o), "<b>(b) -> or<b, <a>(a... *TRUNCATED*");
+        CHECK_EQ(toString(requireType("f3"), o), "<c>(c) -> or<c, <b>(b... *TRUNCATED*");
+    }
+    else
+    {
         LUAU_REQUIRE_NO_ERRORS(result);
 
         ToStringOptions o;
         o.exhaustive = false;
-
-    if (FFlag::DebugLuauDeferredConstraintResolution)
-    {
-        o.maxTypeLength = 30;
-        CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
-        CHECK_EQ(toString(requireType("f1"), o), "<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-        CHECK_EQ(toString(requireType("f2"), o), "<b>(b) -> (<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-        CHECK_EQ(toString(requireType("f3"), o), "<c>(c) -> (<b>(b) -> (<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-    }
-    else
-    {
         o.maxTypeLength = 40;
         CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
         CHECK_EQ(toString(requireType("f1"), o), "(() -> ()) -> () -> ()");
@@ -385,20 +405,42 @@ TEST_CASE_FIXTURE(Fixture, "stringifying_type_is_still_capped_when_exhaustive")
         function f2(f) return f or f1 end
         function f3(f) return f or f2 end
     )");
+
+    if (FFlag::DebugLuauDeferredConstraintResolution)
+    {
+        LUAU_REQUIRE_ERROR_COUNT(3, result);
+        auto err = get<ExplicitFunctionAnnotationRecommended>(result.errors[0]);
+        LUAU_ASSERT(err);
+        CHECK("(...any) -> ()" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+        err = get<ExplicitFunctionAnnotationRecommended>(result.errors[1]);
+        LUAU_ASSERT(err);
+        // FIXME: this recommendation could be better
+        CHECK("<a>(a) -> or<a, (...any) -> ()>" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+        err = get<ExplicitFunctionAnnotationRecommended>(result.errors[2]);
+        LUAU_ASSERT(err);
+        // FIXME: this recommendation could be better
+        CHECK("<a>(a) -> or<a, <b>(b) -> or<b, (...any) -> ()>>" == toString(err->recommendedReturn));
+        REQUIRE(1 == err->recommendedArgs.size());
+        CHECK("unknown" == toString(err->recommendedArgs[0].second));
+
+        ToStringOptions o;
+        o.exhaustive = true;
+        o.maxTypeLength = 20;
+        CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
+        CHECK_EQ(toString(requireType("f1"), o), "<a>(a) -> or<a, () -> ... *TRUNCATED*");
+        CHECK_EQ(toString(requireType("f2"), o), "<b>(b) -> or<b, <a>(a... *TRUNCATED*");
+        CHECK_EQ(toString(requireType("f3"), o), "<c>(c) -> or<c, <b>(b... *TRUNCATED*");
+    }
+    else
+    {
         LUAU_REQUIRE_NO_ERRORS(result);
 
         ToStringOptions o;
         o.exhaustive = true;
-    if (FFlag::DebugLuauDeferredConstraintResolution)
-    {
-        o.maxTypeLength = 30;
-        CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
-        CHECK_EQ(toString(requireType("f1"), o), "<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-        CHECK_EQ(toString(requireType("f2"), o), "<b>(b) -> (<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-        CHECK_EQ(toString(requireType("f3"), o), "<c>(c) -> (<b>(b) -> (<a>(a) -> (() -> ()) | (a & ~(false?))... *TRUNCATED*");
-    }
-    else
-    {
         o.maxTypeLength = 40;
         CHECK_EQ(toString(requireType("f0"), o), "() -> ()");
         CHECK_EQ(toString(requireType("f1"), o), "(() -> ()) -> () -> ()");

tests/TypeInfer.functions.test.cpp

@@ -2351,8 +2351,9 @@ end
     LUAU_REQUIRE_ERRORS(result);
     auto err = get<ExplicitFunctionAnnotationRecommended>(result.errors.back());
     LUAU_ASSERT(err);
-    CHECK("false | number" == toString(err->recommendedReturn));
+    CHECK("number" == toString(err->recommendedReturn));
-    CHECK(err->recommendedArgs.size() == 0);
+    REQUIRE(1 == err->recommendedArgs.size());
+    CHECK("number" == toString(err->recommendedArgs[0].second));
 }
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "tf_suggest_arg_type")
@@ -2673,4 +2674,17 @@ TEST_CASE_FIXTURE(Fixture, "captured_local_is_assigned_a_function")
     LUAU_REQUIRE_NO_ERRORS(result);
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "error_suppression_propagates_through_function_calls")
+{
+    CheckResult result = check(R"(
+        function first(x: any)
+            return pairs(x)(x)
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+
+    CHECK("(any) -> (any?, any)" == toString(requireType("first")));
+}
+
 TEST_SUITE_END();

tests/TypeInfer.loops.test.cpp

@@ -1010,7 +1010,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "iterate_over_properties_nonstrict")
     LUAU_REQUIRE_NO_ERRORS(result);
 }
 
-TEST_CASE_FIXTURE(BuiltinsFixture, "pairs_should_not_add_an_indexer")
+TEST_CASE_FIXTURE(BuiltinsFixture, "pairs_should_not_retroactively_add_an_indexer")
 {
     CheckResult result = check(R"(
         --!strict
@@ -1025,7 +1025,12 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "pairs_should_not_add_an_indexer")
     )");
 
     if (FFlag::DebugLuauDeferredConstraintResolution)
-        LUAU_REQUIRE_ERROR_COUNT(2, result);
+    {
+        // 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
+        // on a table that does.
+        LUAU_REQUIRE_ERROR_COUNT(0, result);
+    }
     else
         LUAU_REQUIRE_ERROR_COUNT(1, result);
 }
@@ -1114,4 +1119,20 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "forin_metatable_iter_mm")
     CHECK_EQ("number", toString(requireTypeAtPosition({6, 21})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "iteration_preserves_error_suppression")
+{
+    CheckResult result = check(R"(
+        function first(x: any)
+            for k, v in pairs(x) do
+                print(k, v)
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+
+    CHECK("any" == toString(requireTypeAtPosition({3, 22})));
+    CHECK("any" == toString(requireTypeAtPosition({3, 25})));
+}
+
 TEST_SUITE_END();

tests/TypeInfer.tables.test.cpp

@@ -21,7 +21,6 @@ LUAU_FASTFLAG(LuauInstantiateInSubtyping);
 LUAU_FASTFLAG(LuauAlwaysCommitInferencesOfFunctionCalls);
 LUAU_FASTFLAG(LuauFixIndexerSubtypingOrdering);
 LUAU_FASTFLAG(DebugLuauSharedSelf);
-LUAU_FASTFLAG(LuauReadWritePropertySyntax);
 LUAU_FASTFLAG(LuauMetatableInstantiationCloneCheck);
 
 LUAU_DYNAMIC_FASTFLAG(LuauImproveNonFunctionCallError)
@@ -2729,7 +2728,9 @@ TEST_CASE_FIXTURE(Fixture, "tables_get_names_from_their_locals")
 
 TEST_CASE_FIXTURE(Fixture, "should_not_unblock_table_type_twice")
 {
-    ScopedFastFlag sff(FFlag::DebugLuauDeferredConstraintResolution, true);
+    // don't run this when the DCR flag isn't set
+    if (!FFlag::DebugLuauDeferredConstraintResolution)
+        return;
 
     check(R"(
         local timer = peek(timerQueue)
@@ -4014,7 +4015,6 @@ TEST_CASE_FIXTURE(Fixture, "identify_all_problematic_table_fields")
 TEST_CASE_FIXTURE(Fixture, "read_and_write_only_table_properties_are_unsupported")
 {
     ScopedFastFlag sff[] = {
-        {FFlag::LuauReadWritePropertySyntax, true},
         {FFlag::DebugLuauDeferredConstraintResolution, false},
     };
 
@@ -4040,8 +4040,6 @@ 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::LuauReadWritePropertySyntax, true};
-
     CheckResult result = check(R"(
         type T = {read [string]: number}
         type U = {write [string]: boolean}
@@ -4155,7 +4153,9 @@ 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::LuauReadWritePropertySyntax, true}, {FFlag::DebugLuauDeferredConstraintResolution, false}};
+    ScopedFastFlag sff[] = {
+        {FFlag::DebugLuauDeferredConstraintResolution, false}
+    };
 
     CheckResult result = check(R"(
         type W = {read x: number}
@@ -4179,7 +4179,9 @@ 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::LuauReadWritePropertySyntax, true}, {FFlag::DebugLuauDeferredConstraintResolution, false}};
+    ScopedFastFlag sff[] = {
+        {FFlag::DebugLuauDeferredConstraintResolution, false}
+    };
 
     CheckResult result = check(R"(
         type T = {read [string]: number}
@@ -4199,7 +4201,9 @@ TEST_CASE_FIXTURE(Fixture, "table_writes_introduce_write_properties")
     if (!FFlag::DebugLuauDeferredConstraintResolution)
         return;
 
-    ScopedFastFlag sff[] = {{FFlag::LuauReadWritePropertySyntax, true}, {FFlag::DebugLuauDeferredConstraintResolution, true}};
+    ScopedFastFlag sff[] = {
+        {FFlag::DebugLuauDeferredConstraintResolution, true}
+    };
 
     CheckResult result = check(R"(
         function oc(player, speaker)
@@ -4439,4 +4443,21 @@ TEST_CASE_FIXTURE(Fixture, "insert_a_and_f_of_a_into_table_res_in_a_loop")
     LUAU_REQUIRE_NO_ERRORS(result);
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "ipairs_adds_an_unbounded_indexer")
+{
+    CheckResult result = check(R"(
+        --!strict
+
+        local a = {}
+        ipairs(a)
+    )");
+
+    // The old solver erroneously leaves a free type dangling here.  The new
+    // solver does better.
+    if (FFlag::DebugLuauDeferredConstraintResolution)
+        CHECK("{unknown}" == toString(requireType("a"), {true}));
+    else
+        CHECK("{a}" == toString(requireType("a"), {true}));
+}
+
 TEST_SUITE_END();

tests/conformance/vector.lua

@@ -4,6 +4,12 @@ print('testing vectors')
 -- detect vector size
 local vector_size = if pcall(function() return vector(0, 0, 0).w end) then 4 else 3
 
+function ecall(fn, ...)
+	local ok, err = pcall(fn, ...)
+	assert(not ok)
+	return err:sub((err:find(": ") or -1) + 2, #err)
+end
+
 -- equality
 assert(vector(1, 2, 3) == vector(1, 2, 3))
 assert(vector(0, 1, 2) == vector(-0, 1, 2))
@@ -92,9 +98,29 @@ assert(nanv ~= nanv);
 -- __index
 assert(vector(1, 2, 2).Magnitude == 3)
 assert(vector(0, 0, 0)['Dot'](vector(1, 2, 4), vector(5, 6, 7)) == 45)
+assert(vector(2, 0, 0).Unit == vector(1, 0, 0))
 
 -- __namecall
 assert(vector(1, 2, 4):Dot(vector(5, 6, 7)) == 45)
+assert(ecall(function() vector(1, 2, 4):Dot() end) == "missing argument #2 (vector expected)")
+assert(ecall(function() vector(1, 2, 4):Dot("a") end) == "invalid argument #2 (vector expected, got string)")
+
+local function doDot1(a: vector, b)
+	return a:Dot(b)
+end
+
+local function doDot2(a: vector, b)
+	return (a:Dot(b))
+end
+
+local v124 = vector(1, 2, 4)
+
+assert(doDot1(v124, vector(5, 6, 7)) == 45)
+assert(doDot2(v124, vector(5, 6, 7)) == 45)
+assert(ecall(function() doDot1(v124, "a") end) == "invalid argument #2 (vector expected, got string)")
+assert(ecall(function() doDot2(v124, "a") end) == "invalid argument #2 (vector expected, got string)")
+assert(select("#", doDot1(v124, vector(5, 6, 7))) == 1)
+assert(select("#", doDot2(v124, vector(5, 6, 7))) == 1)
 
 -- can't use vector with NaN components as table key
 assert(pcall(function() local t = {} t[vector(0/0, 2, 3)] = 1 end) == false)
@@ -102,6 +128,9 @@ assert(pcall(function() local t = {} t[vector(1, 0/0, 3)] = 1 end) == false)
 assert(pcall(function() local t = {} t[vector(1, 2, 0/0)] = 1 end) == false)
 assert(pcall(function() local t = {} rawset(t, vector(0/0, 2, 3), 1) end) == false)
 
+assert(vector(1, 0, 0):Cross(vector(0, 1, 0)) == vector(0, 0, 1))
+assert(vector(0, 1, 0):Cross(vector(1, 0, 0)) == vector(0, 0, -1))
+
 -- make sure we cover both builtin and C impl
 assert(vector(1, 2, 4) == vector("1", "2", "4"))
 

tools/faillist.txt

@@ -4,6 +4,7 @@ AutocompleteTest.anonymous_autofilled_generic_type_pack_vararg
 AutocompleteTest.autocomplete_string_singletons
 AutocompleteTest.do_wrong_compatible_nonself_calls
 AutocompleteTest.string_singleton_as_table_key
+AutocompleteTest.string_singleton_in_if_statement2
 AutocompleteTest.suggest_table_keys
 AutocompleteTest.type_correct_suggestion_for_overloads
 AutocompleteTest.type_correct_suggestion_in_table
@@ -133,9 +134,11 @@ RefinementTest.call_an_incompatible_function_after_using_typeguard
 RefinementTest.dataflow_analysis_can_tell_refinements_when_its_appropriate_to_refine_into_nil_or_never
 RefinementTest.discriminate_from_isa_of_x
 RefinementTest.discriminate_from_truthiness_of_x
-RefinementTest.function_call_with_colon_after_refining_not_to_be_nil
+RefinementTest.free_type_is_equal_to_an_lvalue
 RefinementTest.globals_can_be_narrowed_too
 RefinementTest.isa_type_refinement_must_be_known_ahead_of_time
+RefinementTest.luau_polyfill_isindexkey_refine_conjunction
+RefinementTest.luau_polyfill_isindexkey_refine_conjunction_variant
 RefinementTest.not_t_or_some_prop_of_t
 RefinementTest.refine_a_param_that_got_resolved_during_constraint_solving_stage
 RefinementTest.refine_a_property_of_some_global
@@ -154,6 +157,7 @@ TableTests.a_free_shape_can_turn_into_a_scalar_if_it_is_compatible
 TableTests.a_free_shape_cannot_turn_into_a_scalar_if_it_is_not_compatible
 TableTests.any_when_indexing_into_an_unsealed_table_with_no_indexer_in_nonstrict_mode
 TableTests.array_factory_function
+TableTests.cannot_augment_sealed_table
 TableTests.casting_tables_with_props_into_table_with_indexer2
 TableTests.casting_tables_with_props_into_table_with_indexer3
 TableTests.casting_unsealed_tables_with_props_into_table_with_indexer
@@ -177,6 +181,7 @@ TableTests.generalize_table_argument
 TableTests.generic_table_instantiation_potential_regression
 TableTests.indexer_on_sealed_table_must_unify_with_free_table
 TableTests.indexers_get_quantified_too
+TableTests.inequality_operators_imply_exactly_matching_types
 TableTests.infer_array
 TableTests.infer_indexer_from_array_like_table
 TableTests.infer_indexer_from_its_variable_type_and_unifiable
@@ -206,6 +211,7 @@ TableTests.quantify_even_that_table_was_never_exported_at_all
 TableTests.quantify_metatables_of_metatables_of_table
 TableTests.reasonable_error_when_adding_a_nonexistent_property_to_an_array_like_table
 TableTests.recursive_metatable_type_call
+TableTests.refined_thing_can_be_an_array
 TableTests.right_table_missing_key2
 TableTests.scalar_is_a_subtype_of_a_compatible_polymorphic_shape_type
 TableTests.scalar_is_not_a_subtype_of_a_compatible_polymorphic_shape_type
@@ -214,6 +220,7 @@ TableTests.setmetatable_has_a_side_effect
 TableTests.shared_selfs
 TableTests.shared_selfs_from_free_param
 TableTests.shared_selfs_through_metatables
+TableTests.should_not_unblock_table_type_twice
 TableTests.table_call_metamethod_basic
 TableTests.table_call_metamethod_must_be_callable
 TableTests.table_param_width_subtyping_2
@@ -236,6 +243,8 @@ ToString.named_metatable_toStringNamedFunction
 ToString.no_parentheses_around_cyclic_function_type_in_intersection
 ToString.pick_distinct_names_for_mixed_explicit_and_implicit_generics
 ToString.primitive
+ToString.quit_stringifying_type_when_length_is_exceeded
+ToString.stringifying_type_is_still_capped_when_exhaustive
 ToString.toStringDetailed2
 ToString.toStringErrorPack
 TryUnifyTests.members_of_failed_typepack_unification_are_unified_with_errorType
@@ -332,8 +341,10 @@ TypeInferFunctions.occurs_check_failure_in_function_return_type
 TypeInferFunctions.other_things_are_not_related_to_function
 TypeInferFunctions.param_1_and_2_both_takes_the_same_generic_but_their_arguments_are_incompatible
 TypeInferFunctions.param_1_and_2_both_takes_the_same_generic_but_their_arguments_are_incompatible_2
+TypeInferFunctions.regex_benchmark_string_format_minimization
 TypeInferFunctions.report_exiting_without_return_nonstrict
 TypeInferFunctions.return_type_by_overload
+TypeInferFunctions.tf_suggest_return_type
 TypeInferFunctions.too_few_arguments_variadic
 TypeInferFunctions.too_few_arguments_variadic_generic
 TypeInferFunctions.too_few_arguments_variadic_generic2
@@ -406,6 +417,7 @@ TypeSingletons.error_detailed_tagged_union_mismatch_bool
 TypeSingletons.error_detailed_tagged_union_mismatch_string
 TypeSingletons.overloaded_function_call_with_singletons_mismatch
 TypeSingletons.return_type_of_f_is_not_widened
+TypeSingletons.singletons_stick_around_under_assignment
 TypeSingletons.table_properties_type_error_escapes
 TypeSingletons.widen_the_supertype_if_it_is_free_and_subtype_has_singleton
 TypeStatesTest.typestates_preserve_error_suppression_properties