Sync to upstream/release/634 (#1325)

# What's Changed?

- Performance improvement in the old solver
- Bugfixes in the new solver

## Old Solver

- Mark types that do not need instantiation when being exported to
prevent unnecessary work from being done

## New Solver

- Refactored instances of "type family" with "type function"
- Index-out-of-bounds bug fix in the resolution resolver
- Subtyping reasonings are merged only if all failed

---
### Internal Contributors

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

---------

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

Analysis/include/Luau/Constraint.h

@@ -242,7 +242,7 @@ struct UnpackConstraint
 
 // ty ~ reduce ty
 //
-// Try to reduce ty, if it is a TypeFamilyInstanceType. Otherwise, do nothing.
+// Try to reduce ty, if it is a TypeFunctionInstanceType. Otherwise, do nothing.
 struct ReduceConstraint
 {
     TypeId ty;

Analysis/include/Luau/ConstraintGenerator.h

@@ -343,9 +343,9 @@ private:
     void reportError(Location location, TypeErrorData err);
     void reportCodeTooComplex(Location location);
 
-    // make a union type family of these two types
+    // make a union type function of these two types
     TypeId makeUnion(const ScopePtr& scope, Location location, TypeId lhs, TypeId rhs);
-    // make an intersect type family of these two types
+    // make an intersect type function of these two types
     TypeId makeIntersect(const ScopePtr& scope, Location location, TypeId lhs, TypeId rhs);
 
     /** Scan the program for global definitions.
@@ -370,8 +370,8 @@ private:
      */
     std::vector<std::optional<TypeId>> getExpectedCallTypesForFunctionOverloads(const TypeId fnType);
 
-    TypeId createTypeFamilyInstance(
+    TypeId createTypeFunctionInstance(
-        const TypeFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments, const ScopePtr& scope, Location location);
+        const TypeFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments, const ScopePtr& scope, Location location);
 };
 
 /** Borrow a vector of pointers from a vector of owning pointers to constraints.

Analysis/include/Luau/Error.h

@@ -334,11 +334,11 @@ struct DynamicPropertyLookupOnClassesUnsafe
     bool operator==(const DynamicPropertyLookupOnClassesUnsafe& rhs) const;
 };
 
-struct UninhabitedTypeFamily
+struct UninhabitedTypeFunction
 {
     TypeId ty;
 
-    bool operator==(const UninhabitedTypeFamily& rhs) const;
+    bool operator==(const UninhabitedTypeFunction& rhs) const;
 };
 
 struct ExplicitFunctionAnnotationRecommended
@@ -348,11 +348,11 @@ struct ExplicitFunctionAnnotationRecommended
     bool operator==(const ExplicitFunctionAnnotationRecommended& rhs) const;
 };
 
-struct UninhabitedTypePackFamily
+struct UninhabitedTypePackFunction
 {
     TypePackId tp;
 
-    bool operator==(const UninhabitedTypePackFamily& rhs) const;
+    bool operator==(const UninhabitedTypePackFunction& rhs) const;
 };
 
 struct WhereClauseNeeded
@@ -449,7 +449,7 @@ using TypeErrorData =
         CodeTooComplex, UnificationTooComplex, UnknownPropButFoundLikeProp, GenericError, InternalError, CannotCallNonFunction, ExtraInformation,
         DeprecatedApiUsed, ModuleHasCyclicDependency, IllegalRequire, FunctionExitsWithoutReturning, DuplicateGenericParameter, CannotAssignToNever,
         CannotInferBinaryOperation, MissingProperties, SwappedGenericTypeParameter, OptionalValueAccess, MissingUnionProperty, TypesAreUnrelated,
-        NormalizationTooComplex, TypePackMismatch, DynamicPropertyLookupOnClassesUnsafe, UninhabitedTypeFamily, UninhabitedTypePackFamily,
+        NormalizationTooComplex, TypePackMismatch, DynamicPropertyLookupOnClassesUnsafe, UninhabitedTypeFunction, UninhabitedTypePackFunction,
         WhereClauseNeeded, PackWhereClauseNeeded, CheckedFunctionCallError, NonStrictFunctionDefinitionError, PropertyAccessViolation,
         CheckedFunctionIncorrectArgs, UnexpectedTypeInSubtyping, UnexpectedTypePackInSubtyping, ExplicitFunctionAnnotationRecommended>;
 

Analysis/include/Luau/Instantiation.h

@@ -5,6 +5,7 @@
 #include "Luau/Substitution.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/Unifiable.h"
+#include "Luau/VisitType.h"
 
 namespace Luau
 {
@@ -72,6 +73,59 @@ struct Instantiation : Substitution
     TypePackId clean(TypePackId tp) override;
 };
 
+// Used to find if a FunctionType requires generic type cleanup during instantiation
+struct GenericTypeFinder : TypeOnceVisitor
+{
+    bool found = false;
+
+    bool visit(TypeId ty) override
+    {
+        return !found;
+    }
+
+    bool visit(TypePackId ty) override
+    {
+        return !found;
+    }
+
+    bool visit(TypeId ty, const Luau::FunctionType& ftv) override
+    {
+        if (ftv.hasNoFreeOrGenericTypes)
+            return false;
+
+        if (!ftv.generics.empty() || !ftv.genericPacks.empty())
+            found = true;
+
+        return !found;
+    }
+
+    bool visit(TypeId ty, const Luau::TableType& ttv) override
+    {
+        if (ttv.state == Luau::TableState::Generic)
+            found = true;
+
+        return !found;
+    }
+
+    bool visit(TypeId ty, const Luau::GenericType&) override
+    {
+        found = true;
+        return false;
+    }
+
+    bool visit(TypePackId ty, const Luau::GenericTypePack&) override
+    {
+        found = true;
+        return false;
+    }
+
+    bool visit(TypeId ty, const Luau::ClassType&) override
+    {
+        // During function instantiation, classes are not traversed even if they have generics
+        return false;
+    }
+};
+
 /** Attempt to instantiate a type.  Only used under local type inference.
  *
  * When given a generic function type, instantiate() will return a copy with the

Analysis/include/Luau/Subtyping.h

@@ -5,7 +5,7 @@
 #include "Luau/TypeFwd.h"
 #include "Luau/TypePairHash.h"
 #include "Luau/TypePath.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypeCheckLimits.h"
 #include "Luau/DenseHash.h"
 
@@ -114,7 +114,7 @@ struct SubtypingEnvironment
     DenseHashMap<std::pair<TypeId, TypeId>, SubtypingResult, TypePairHash> ephemeralCache{{}};
 
     /// Applies `mappedGenerics` to the given type.
-    /// This is used specifically to substitute for generics in type family instances.
+    /// This is used specifically to substitute for generics in type function instances.
     std::optional<TypeId> applyMappedGenerics(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId ty);
 };
 
@@ -219,8 +219,8 @@ private:
     SubtypingResult isCovariantWith(SubtypingEnvironment& env, const TypeIds& subTypes, const TypeIds& superTypes);
 
     SubtypingResult isCovariantWith(SubtypingEnvironment& env, const VariadicTypePack* subVariadic, const VariadicTypePack* superVariadic);
-    SubtypingResult isCovariantWith(SubtypingEnvironment& env, const TypeFamilyInstanceType* subFamilyInstance, const TypeId superTy);
+    SubtypingResult isCovariantWith(SubtypingEnvironment& env, const TypeFunctionInstanceType* subFamilyInstance, const TypeId superTy);
-    SubtypingResult isCovariantWith(SubtypingEnvironment& env, const TypeId subTy, const TypeFamilyInstanceType* superFamilyInstance);
+    SubtypingResult isCovariantWith(SubtypingEnvironment& env, const TypeId subTy, const TypeFunctionInstanceType* superFamilyInstance);
 
     bool bindGeneric(SubtypingEnvironment& env, TypeId subTp, TypeId superTp);
     bool bindGeneric(SubtypingEnvironment& env, TypePackId subTp, TypePackId superTp);
@@ -228,7 +228,7 @@ private:
     template<typename T, typename Container>
     TypeId makeAggregateType(const Container& container, TypeId orElse);
 
-    std::pair<TypeId, ErrorVec> handleTypeFamilyReductionResult(const TypeFamilyInstanceType* familyInstance);
+    std::pair<TypeId, ErrorVec> handleTypeFunctionReductionResult(const TypeFunctionInstanceType* familyInstance);
 
     [[noreturn]] void unexpected(TypeId ty);
     [[noreturn]] void unexpected(TypePackId tp);

Analysis/include/Luau/Type.h

@@ -32,7 +32,7 @@ struct TypeArena;
 struct Scope;
 using ScopePtr = std::shared_ptr<Scope>;
 
-struct TypeFamily;
+struct TypeFunction;
 struct Constraint;
 
 /**
@@ -528,34 +528,34 @@ struct ClassType
 };
 
 /**
- * An instance of a type family that has not yet been reduced to a more concrete
+ * An instance of a type function that has not yet been reduced to a more concrete
  * type. The constraint solver receives a constraint to reduce each
- * TypeFamilyInstanceType to a concrete type. A design detail is important to
+ * TypeFunctionInstanceType to a concrete type. A design detail is important to
- * note here: the parameters for this instantiation of the type family are
+ * note here: the parameters for this instantiation of the type function are
  * contained within this type, so that they can be substituted.
  */
-struct TypeFamilyInstanceType
+struct TypeFunctionInstanceType
 {
-    NotNull<const TypeFamily> family;
+    NotNull<const TypeFunction> family;
 
     std::vector<TypeId> typeArguments;
     std::vector<TypePackId> packArguments;
 
-    TypeFamilyInstanceType(NotNull<const TypeFamily> family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
+    TypeFunctionInstanceType(NotNull<const TypeFunction> family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
         : family(family)
         , typeArguments(typeArguments)
         , packArguments(packArguments)
     {
     }
 
-    TypeFamilyInstanceType(const TypeFamily& family, std::vector<TypeId> typeArguments)
+    TypeFunctionInstanceType(const TypeFunction& family, std::vector<TypeId> typeArguments)
         : family{&family}
         , typeArguments(typeArguments)
         , packArguments{}
     {
     }
 
-    TypeFamilyInstanceType(const TypeFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
+    TypeFunctionInstanceType(const TypeFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
         : family{&family}
         , typeArguments(typeArguments)
         , packArguments(packArguments)
@@ -659,7 +659,7 @@ using ErrorType = Unifiable::Error;
 
 using TypeVariant =
     Unifiable::Variant<TypeId, FreeType, GenericType, PrimitiveType, SingletonType, BlockedType, PendingExpansionType, FunctionType, TableType,
-        MetatableType, ClassType, AnyType, UnionType, IntersectionType, LazyType, UnknownType, NeverType, NegationType, TypeFamilyInstanceType>;
+        MetatableType, ClassType, AnyType, UnionType, IntersectionType, LazyType, UnknownType, NeverType, NegationType, TypeFunctionInstanceType>;
 
 struct Type final
 {

Analysis/include/Luau/TypeArena.h

@@ -49,10 +49,10 @@ struct TypeArena
         return addTypePack(TypePackVar(std::move(tp)));
     }
 
-    TypeId addTypeFamily(const TypeFamily& family, std::initializer_list<TypeId> types);
+    TypeId addTypeFunction(const TypeFunction& family, std::initializer_list<TypeId> types);
-    TypeId addTypeFamily(const TypeFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments = {});
+    TypeId addTypeFunction(const TypeFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments = {});
-    TypePackId addTypePackFamily(const TypePackFamily& family, std::initializer_list<TypeId> types);
+    TypePackId addTypePackFunction(const TypePackFunction& family, std::initializer_list<TypeId> types);
-    TypePackId addTypePackFamily(const TypePackFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments = {});
+    TypePackId addTypePackFunction(const TypePackFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments = {});
 };
 
 void freeze(TypeArena& arena);

Analysis/include/Luau/TypeFamilyReductionGuesser.h

@@ -1,85 +0,0 @@
-// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-
-#pragma once
-
-#include "Luau/Ast.h"
-#include "Luau/VecDeque.h"
-#include "Luau/DenseHash.h"
-#include "Luau/TypeFamily.h"
-#include "Luau/Type.h"
-#include "Luau/TypePack.h"
-#include "Luau/TypeUtils.h"
-#include "Luau/Normalize.h"
-#include "Luau/TypeFwd.h"
-#include "Luau/VisitType.h"
-#include "Luau/NotNull.h"
-#include "TypeArena.h"
-
-namespace Luau
-{
-
-struct TypeFamilyReductionGuessResult
-{
-    std::vector<std::pair<std::string, TypeId>> guessedFunctionAnnotations;
-    TypeId guessedReturnType;
-    bool shouldRecommendAnnotation = true;
-};
-
-// An Inference result for a type family is a list of types corresponding to the guessed argument types, followed by a type for the result
-struct TypeFamilyInferenceResult
-{
-    std::vector<TypeId> operandInference;
-    TypeId familyResultInference;
-};
-
-struct TypeFamilyReductionGuesser
-{
-    // Tracks our hypothesis about what a type family reduces to
-    DenseHashMap<TypeId, TypeId> familyReducesTo{nullptr};
-    // Tracks our constraints on type family operands
-    DenseHashMap<TypeId, TypeId> substitutable{nullptr};
-    // List of instances to try progress
-    VecDeque<TypeId> toInfer;
-    DenseHashSet<TypeId> cyclicInstances{nullptr};
-
-    // Utilities
-    NotNull<TypeArena> arena;
-    NotNull<BuiltinTypes> builtins;
-    NotNull<Normalizer> normalizer;
-
-    TypeFamilyReductionGuesser(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Normalizer> normalizer);
-
-    std::optional<TypeId> guess(TypeId typ);
-    std::optional<TypePackId> guess(TypePackId typ);
-    TypeFamilyReductionGuessResult guessTypeFamilyReductionForFunction(const AstExprFunction& expr, const FunctionType* ftv, TypeId retTy);
-
-private:
-    std::optional<TypeId> guessType(TypeId arg);
-    void dumpGuesses();
-
-    bool isNumericBinopFamily(const TypeFamilyInstanceType& instance);
-    bool isComparisonFamily(const TypeFamilyInstanceType& instance);
-    bool isOrAndFamily(const TypeFamilyInstanceType& instance);
-    bool isNotFamily(const TypeFamilyInstanceType& instance);
-    bool isLenFamily(const TypeFamilyInstanceType& instance);
-    bool isUnaryMinus(const TypeFamilyInstanceType& instance);
-
-    // Operand is assignable if it looks like a cyclic family instance, or a generic type
-    bool operandIsAssignable(TypeId ty);
-    std::optional<TypeId> tryAssignOperandType(TypeId ty);
-
-    std::shared_ptr<const NormalizedType> normalize(TypeId ty);
-    void step();
-    void infer();
-    bool done();
-
-    bool isFunctionGenericsSaturated(const FunctionType& ftv, DenseHashSet<TypeId>& instanceArgs);
-    void inferTypeFamilySubstitutions(TypeId ty, const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferNumericBinopFamily(const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferComparisonFamily(const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferOrAndFamily(const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferNotFamily(const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferLenFamily(const TypeFamilyInstanceType* instance);
-    TypeFamilyInferenceResult inferUnaryMinusFamily(const TypeFamilyInstanceType* instance);
-};
-} // namespace Luau

Analysis/include/Luau/TypeFunction.h

@@ -18,7 +18,7 @@ struct TypeArena;
 struct TxnLog;
 class Normalizer;
 
-struct TypeFamilyContext
+struct TypeFunctionContext
 {
     NotNull<TypeArena> arena;
     NotNull<BuiltinTypes> builtins;
@@ -27,12 +27,12 @@ struct TypeFamilyContext
     NotNull<InternalErrorReporter> ice;
     NotNull<TypeCheckLimits> limits;
 
-    // nullptr if the type family is being reduced outside of the constraint solver.
+    // nullptr if the type function is being reduced outside of the constraint solver.
     ConstraintSolver* solver;
     // The constraint being reduced in this run of the reduction
     const Constraint* constraint;
 
-    TypeFamilyContext(NotNull<ConstraintSolver> cs, NotNull<Scope> scope, NotNull<const Constraint> constraint)
+    TypeFunctionContext(NotNull<ConstraintSolver> cs, NotNull<Scope> scope, NotNull<const Constraint> constraint)
         : arena(cs->arena)
         , builtins(cs->builtinTypes)
         , scope(scope)
@@ -44,7 +44,7 @@ struct TypeFamilyContext
     {
     }
 
-    TypeFamilyContext(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Scope> scope, NotNull<Normalizer> normalizer,
+    TypeFunctionContext(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Scope> scope, NotNull<Normalizer> normalizer,
         NotNull<InternalErrorReporter> ice, NotNull<TypeCheckLimits> limits)
         : arena(arena)
         , builtins(builtins)
@@ -64,13 +64,13 @@ struct TypeFamilyContext
 /// may have concretely failed to reduce the type, or may simply be stuck
 /// without more information.
 template<typename Ty>
-struct TypeFamilyReductionResult
+struct TypeFunctionReductionResult
 {
-    /// The result of the reduction, if any. If this is nullopt, the family
+    /// The result of the reduction, if any. If this is nullopt, the type function
     /// could not be reduced.
     std::optional<Ty> result;
     /// Whether the result is uninhabited: whether we know, unambiguously and
-    /// permanently, whether this type family reduction results in an
+    /// permanently, whether this type function reduction results in an
     /// uninhabitable type. This will trigger an error to be reported.
     bool uninhabited;
     /// Any types that need to be progressed or mutated before the reduction may
@@ -83,33 +83,33 @@ struct TypeFamilyReductionResult
 
 template<typename T>
 using ReducerFunction =
-    std::function<TypeFamilyReductionResult<T>(T, const std::vector<TypeId>&, const std::vector<TypePackId>&, NotNull<TypeFamilyContext>)>;
+    std::function<TypeFunctionReductionResult<T>(T, const std::vector<TypeId>&, const std::vector<TypePackId>&, NotNull<TypeFunctionContext>)>;
 
 /// Represents a type function that may be applied to map a series of types and
 /// type packs to a single output type.
-struct TypeFamily
+struct TypeFunction
 {
-    /// The human-readable name of the type family. Used to stringify instance
+    /// The human-readable name of the type function. Used to stringify instance
     /// types.
     std::string name;
 
-    /// The reducer function for the type family.
+    /// The reducer function for the type function.
     ReducerFunction<TypeId> reducer;
 };
 
 /// Represents a type function that may be applied to map a series of types and
 /// type packs to a single output type pack.
-struct TypePackFamily
+struct TypePackFunction
 {
-    /// The human-readable name of the type pack family. Used to stringify
+    /// The human-readable name of the type pack function. Used to stringify
     /// instance packs.
     std::string name;
 
-    /// The reducer function for the type pack family.
+    /// The reducer function for the type pack function.
     ReducerFunction<TypePackId> reducer;
 };
 
-struct FamilyGraphReductionResult
+struct FunctionGraphReductionResult
 {
     ErrorVec errors;
     DenseHashSet<TypeId> blockedTypes{nullptr};
@@ -119,7 +119,7 @@ struct FamilyGraphReductionResult
 };
 
 /**
- * Attempt to reduce all instances of any type or type pack family in the type
+ * Attempt to reduce all instances of any type or type pack functions in the type
  * graph provided.
  *
  * @param entrypoint the entry point to the type graph.
@@ -130,10 +130,10 @@ struct FamilyGraphReductionResult
  * @param normalizer the normalizer to use when normalizing types
  * @param ice the internal error reporter to use for ICEs
  */
-FamilyGraphReductionResult reduceFamilies(TypeId entrypoint, Location location, TypeFamilyContext, bool force = false);
+FunctionGraphReductionResult reduceTypeFunctions(TypeId entrypoint, Location location, TypeFunctionContext, bool force = false);
 
 /**
- * Attempt to reduce all instances of any type or type pack family in the type
+ * Attempt to reduce all instances of any type or type pack functions in the type
  * graph provided.
  *
  * @param entrypoint the entry point to the type graph.
@@ -144,47 +144,46 @@ FamilyGraphReductionResult reduceFamilies(TypeId entrypoint, Location location,
  * @param normalizer the normalizer to use when normalizing types
  * @param ice the internal error reporter to use for ICEs
  */
-FamilyGraphReductionResult reduceFamilies(TypePackId entrypoint, Location location, TypeFamilyContext, bool force = false);
+FunctionGraphReductionResult reduceTypeFunctions(TypePackId entrypoint, Location location, TypeFunctionContext, bool force = false);
 
-struct BuiltinTypeFamilies
+struct BuiltinTypeFunctions
 {
-    BuiltinTypeFamilies();
+    BuiltinTypeFunctions();
 
-    TypeFamily notFamily;
+    TypeFunction notFunc;
-    TypeFamily lenFamily;
+    TypeFunction lenFunc;
-    TypeFamily unmFamily;
+    TypeFunction unmFunc;
 
-    TypeFamily addFamily;
+    TypeFunction addFunc;
-    TypeFamily subFamily;
+    TypeFunction subFunc;
-    TypeFamily mulFamily;
+    TypeFunction mulFunc;
-    TypeFamily divFamily;
+    TypeFunction divFunc;
-    TypeFamily idivFamily;
+    TypeFunction idivFunc;
-    TypeFamily powFamily;
+    TypeFunction powFunc;
-    TypeFamily modFamily;
+    TypeFunction modFunc;
 
-    TypeFamily concatFamily;
+    TypeFunction concatFunc;
 
-    TypeFamily andFamily;
+    TypeFunction andFunc;
-    TypeFamily orFamily;
+    TypeFunction orFunc;
 
-    TypeFamily ltFamily;
+    TypeFunction ltFunc;
-    TypeFamily leFamily;
+    TypeFunction leFunc;
-    TypeFamily eqFamily;
+    TypeFunction eqFunc;
 
-    TypeFamily refineFamily;
+    TypeFunction refineFunc;
-    TypeFamily singletonFamily;
+    TypeFunction singletonFunc;
-    TypeFamily unionFamily;
+    TypeFunction unionFunc;
-    TypeFamily intersectFamily;
+    TypeFunction intersectFunc;
 
-    TypeFamily keyofFamily;
+    TypeFunction keyofFunc;
-    TypeFamily rawkeyofFamily;
+    TypeFunction rawkeyofFunc;
-
+    TypeFunction indexFunc;
-    TypeFamily indexFamily;
+    TypeFunction rawgetFunc;
-    TypeFamily rawgetFamily;
 
     void addToScope(NotNull<TypeArena> arena, NotNull<Scope> scope) const;
 };
 
-const BuiltinTypeFamilies& builtinTypeFunctions();
+const BuiltinTypeFunctions& builtinTypeFunctions();
 
 } // namespace Luau

Analysis/include/Luau/TypeFunctionReductionGuesser.h

@@ -0,0 +1,85 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+
+#pragma once
+
+#include "Luau/Ast.h"
+#include "Luau/VecDeque.h"
+#include "Luau/DenseHash.h"
+#include "Luau/TypeFunction.h"
+#include "Luau/Type.h"
+#include "Luau/TypePack.h"
+#include "Luau/TypeUtils.h"
+#include "Luau/Normalize.h"
+#include "Luau/TypeFwd.h"
+#include "Luau/VisitType.h"
+#include "Luau/NotNull.h"
+#include "TypeArena.h"
+
+namespace Luau
+{
+
+struct TypeFunctionReductionGuessResult
+{
+    std::vector<std::pair<std::string, TypeId>> guessedFunctionAnnotations;
+    TypeId guessedReturnType;
+    bool shouldRecommendAnnotation = true;
+};
+
+// An Inference result for a type function is a list of types corresponding to the guessed argument types, followed by a type for the result
+struct TypeFunctionInferenceResult
+{
+    std::vector<TypeId> operandInference;
+    TypeId familyResultInference;
+};
+
+struct TypeFunctionReductionGuesser
+{
+    // Tracks our hypothesis about what a type function reduces to
+    DenseHashMap<TypeId, TypeId> familyReducesTo{nullptr};
+    // Tracks our constraints on type function operands
+    DenseHashMap<TypeId, TypeId> substitutable{nullptr};
+    // List of instances to try progress
+    VecDeque<TypeId> toInfer;
+    DenseHashSet<TypeId> cyclicInstances{nullptr};
+
+    // Utilities
+    NotNull<TypeArena> arena;
+    NotNull<BuiltinTypes> builtins;
+    NotNull<Normalizer> normalizer;
+
+    TypeFunctionReductionGuesser(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Normalizer> normalizer);
+
+    std::optional<TypeId> guess(TypeId typ);
+    std::optional<TypePackId> guess(TypePackId typ);
+    TypeFunctionReductionGuessResult guessTypeFunctionReductionForFunctionExpr(const AstExprFunction& expr, const FunctionType* ftv, TypeId retTy);
+
+private:
+    std::optional<TypeId> guessType(TypeId arg);
+    void dumpGuesses();
+
+    bool isNumericBinopFamily(const TypeFunctionInstanceType& instance);
+    bool isComparisonFamily(const TypeFunctionInstanceType& instance);
+    bool isOrAndFamily(const TypeFunctionInstanceType& instance);
+    bool isNotFamily(const TypeFunctionInstanceType& instance);
+    bool isLenFamily(const TypeFunctionInstanceType& instance);
+    bool isUnaryMinus(const TypeFunctionInstanceType& instance);
+
+    // Operand is assignable if it looks like a cyclic family instance, or a generic type
+    bool operandIsAssignable(TypeId ty);
+    std::optional<TypeId> tryAssignOperandType(TypeId ty);
+
+    std::shared_ptr<const NormalizedType> normalize(TypeId ty);
+    void step();
+    void infer();
+    bool done();
+
+    bool isFunctionGenericsSaturated(const FunctionType& ftv, DenseHashSet<TypeId>& instanceArgs);
+    void inferTypeFunctionSubstitutions(TypeId ty, const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferNumericBinopFamily(const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferComparisonFamily(const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferOrAndFamily(const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferNotFamily(const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferLenFamily(const TypeFunctionInstanceType* instance);
+    TypeFunctionInferenceResult inferUnaryMinusFamily(const TypeFunctionInstanceType* instance);
+};
+} // namespace Luau

Analysis/include/Luau/TypeFwd.h

@@ -37,7 +37,7 @@ struct LazyType;
 struct UnknownType;
 struct NeverType;
 struct NegationType;
-struct TypeFamilyInstanceType;
+struct TypeFunctionInstanceType;
 
 struct TypePackVar;
 using TypePackId = const TypePackVar*;
@@ -47,7 +47,7 @@ struct GenericTypePack;
 struct TypePack;
 struct VariadicTypePack;
 struct BlockedTypePack;
-struct TypeFamilyInstanceTypePack;
+struct TypeFunctionInstanceTypePack;
 
 using Name = std::string;
 using ModuleName = std::string;

Analysis/include/Luau/TypePack.h

@@ -15,13 +15,13 @@ namespace Luau
 {
 
 struct TypeArena;
-struct TypePackFamily;
+struct TypePackFunction;
 struct TxnLog;
 
 struct TypePack;
 struct VariadicTypePack;
 struct BlockedTypePack;
-struct TypeFamilyInstanceTypePack;
+struct TypeFunctionInstanceTypePack;
 
 struct FreeTypePack
 {
@@ -55,7 +55,7 @@ using BoundTypePack = Unifiable::Bound<TypePackId>;
 using ErrorTypePack = Unifiable::Error;
 
 using TypePackVariant =
-    Unifiable::Variant<TypePackId, FreeTypePack, GenericTypePack, TypePack, VariadicTypePack, BlockedTypePack, TypeFamilyInstanceTypePack>;
+    Unifiable::Variant<TypePackId, FreeTypePack, GenericTypePack, TypePack, VariadicTypePack, BlockedTypePack, TypeFunctionInstanceTypePack>;
 
 /* A TypePack is a rope-like string of TypeIds.  We use this structure to encode
  * notions like packs of unknown length and packs of any length, as well as more
@@ -88,11 +88,11 @@ struct BlockedTypePack
 };
 
 /**
- * Analogous to a TypeFamilyInstanceType.
+ * Analogous to a TypeFunctionInstanceType.
  */
-struct TypeFamilyInstanceTypePack
+struct TypeFunctionInstanceTypePack
 {
-    NotNull<const TypePackFamily> family;
+    NotNull<const TypePackFunction> family;
 
     std::vector<TypeId> typeArguments;
     std::vector<TypePackId> packArguments;

Analysis/include/Luau/VisitType.h

@@ -7,6 +7,7 @@
 #include "Luau/RecursionCounter.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
+#include "Type.h"
 
 LUAU_FASTINT(LuauVisitRecursionLimit)
 LUAU_FASTFLAG(LuauBoundLazyTypes2)
@@ -65,7 +66,7 @@ inline void unsee(DenseHashSet<void*>& seen, const void* tv)
 } // namespace visit_detail
 
 // recursion counter is equivalent here, but we'd like a better name to express the intent.
-using TypeFamilyDepthCounter = RecursionCounter;
+using TypeFunctionDepthCounter = RecursionCounter;
 
 template<typename S>
 struct GenericTypeVisitor
@@ -75,7 +76,7 @@ struct GenericTypeVisitor
     Set seen;
     bool skipBoundTypes = false;
     int recursionCounter = 0;
-    int typeFamilyDepth = 0;
+    int typeFunctionDepth = 0;
 
     GenericTypeVisitor() = default;
 
@@ -164,7 +165,7 @@ struct GenericTypeVisitor
     {
         return visit(ty);
     }
-    virtual bool visit(TypeId ty, const TypeFamilyInstanceType& tfit)
+    virtual bool visit(TypeId ty, const TypeFunctionInstanceType& tfit)
     {
         return visit(ty);
     }
@@ -201,7 +202,7 @@ struct GenericTypeVisitor
     {
         return visit(tp);
     }
-    virtual bool visit(TypePackId tp, const TypeFamilyInstanceTypePack& tfitp)
+    virtual bool visit(TypePackId tp, const TypeFunctionInstanceTypePack& tfitp)
     {
         return visit(tp);
     }
@@ -415,9 +416,9 @@ struct GenericTypeVisitor
             if (visit(ty, *ntv))
                 traverse(ntv->ty);
         }
-        else if (auto tfit = get<TypeFamilyInstanceType>(ty))
+        else if (auto tfit = get<TypeFunctionInstanceType>(ty))
         {
-            TypeFamilyDepthCounter tfdc{&typeFamilyDepth};
+            TypeFunctionDepthCounter tfdc{&typeFunctionDepth};
 
             if (visit(ty, *tfit))
             {
@@ -477,9 +478,9 @@ struct GenericTypeVisitor
         }
         else if (auto btp = get<BlockedTypePack>(tp))
             visit(tp, *btp);
-        else if (auto tfitp = get<TypeFamilyInstanceTypePack>(tp))
+        else if (auto tfitp = get<TypeFunctionInstanceTypePack>(tp))
         {
-            TypeFamilyDepthCounter tfdc{&typeFamilyDepth};
+            TypeFunctionDepthCounter tfdc{&typeFunctionDepth};
 
             if (visit(tp, *tfitp))
             {

Analysis/src/BuiltinDefinitions.cpp

@@ -10,7 +10,7 @@
 #include "Luau/ConstraintGenerator.h"
 #include "Luau/NotNull.h"
 #include "Luau/TypeInfer.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
 #include "Luau/TypeUtils.h"
@@ -312,8 +312,8 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
     {
         // declare function assert<T>(value: T, errorMessage: string?): intersect<T, ~(false?)>
         TypeId genericT = arena.addType(GenericType{"T"});
-        TypeId refinedTy = arena.addType(TypeFamilyInstanceType{
+        TypeId refinedTy = arena.addType(TypeFunctionInstanceType{
-            NotNull{&builtinTypeFunctions().intersectFamily}, {genericT, arena.addType(NegationType{builtinTypes->falsyType})}, {}});
+            NotNull{&builtinTypeFunctions().intersectFunc}, {genericT, arena.addType(NegationType{builtinTypes->falsyType})}, {}});
 
         TypeId assertTy = arena.addType(FunctionType{
             {genericT}, {}, arena.addTypePack(TypePack{{genericT, builtinTypes->optionalStringType}}), arena.addTypePack(TypePack{{refinedTy}})});

Analysis/src/Clone.cpp

@@ -388,7 +388,7 @@ private:
         t->ty = shallowClone(t->ty);
     }
 
-    void cloneChildren(TypeFamilyInstanceType* t)
+    void cloneChildren(TypeFunctionInstanceType* t)
     {
         for (TypeId& ty : t->typeArguments)
             ty = shallowClone(ty);
@@ -432,7 +432,7 @@ private:
             t->tail = shallowClone(*t->tail);
     }
 
-    void cloneChildren(TypeFamilyInstanceTypePack* t)
+    void cloneChildren(TypeFunctionInstanceTypePack* t)
     {
         for (TypeId& ty : t->typeArguments)
             ty = shallowClone(ty);

Analysis/src/ConstraintGenerator.cpp

@@ -16,7 +16,7 @@
 #include "Luau/StringUtils.h"
 #include "Luau/TableLiteralInference.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
@@ -432,7 +432,7 @@ void ConstraintGenerator::computeRefinement(const ScopePtr& scope, Location loca
             discriminantTy = arena->addType(NegationType{discriminantTy});
 
         if (eq)
-            discriminantTy = createTypeFamilyInstance(builtinTypeFunctions().singletonFamily, {discriminantTy}, {}, scope, location);
+            discriminantTy = createTypeFunctionInstance(builtinTypeFunctions().singletonFunc, {discriminantTy}, {}, scope, location);
 
         for (const RefinementKey* key = proposition->key; key; key = key->parent)
         {
@@ -544,7 +544,7 @@ void ConstraintGenerator::applyRefinements(const ScopePtr& scope, Location locat
             {
                 if (mustDeferIntersection(ty) || mustDeferIntersection(dt))
                 {
-                    TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().refineFamily, {ty, dt}, {}, scope, location);
+                    TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().refineFunc, {ty, dt}, {}, scope, location);
 
                     ty = resultType;
                 }
@@ -2090,17 +2090,17 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprUnary* unary)
     {
     case AstExprUnary::Op::Not:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().notFamily, {operandType}, {}, scope, unary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().notFunc, {operandType}, {}, scope, unary->location);
         return Inference{resultType, refinementArena.negation(refinement)};
     }
     case AstExprUnary::Op::Len:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().lenFamily, {operandType}, {}, scope, unary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().lenFunc, {operandType}, {}, scope, unary->location);
         return Inference{resultType, refinementArena.negation(refinement)};
     }
     case AstExprUnary::Op::Minus:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().unmFamily, {operandType}, {}, scope, unary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().unmFunc, {operandType}, {}, scope, unary->location);
         return Inference{resultType, refinementArena.negation(refinement)};
     }
     default: // msvc can't prove that this is exhaustive.
@@ -2116,75 +2116,75 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprBinary* binar
     {
     case AstExprBinary::Op::Add:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().addFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().addFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Sub:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().subFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().subFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Mul:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().mulFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().mulFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Div:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().divFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().divFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::FloorDiv:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().idivFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().idivFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Pow:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().powFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().powFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Mod:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().modFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().modFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Concat:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().concatFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().concatFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::And:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().andFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().andFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Or:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().orFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().orFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::CompareLt:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().ltFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().ltFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::CompareGe:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().ltFamily,
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().ltFunc,
             {rightType, leftType}, // lua decided that `__ge(a, b)` is instead just `__lt(b, a)`
             {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::CompareLe:
     {
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().leFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().leFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::CompareGt:
     {
-        TypeId resultType = createTypeFamilyInstance(
+        TypeId resultType = createTypeFunctionInstance(
-builtinTypeFunctions().leFamily,
+builtinTypeFunctions().leFunc,
             {rightType, leftType}, // lua decided that `__gt(a, b)` is instead just `__le(b, a)`
             {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
@@ -2206,7 +2206,7 @@ builtinTypeFunctions().leFamily,
         else if (rightSubscripted)
             rightType = makeUnion(scope, binary->location, rightType, builtinTypes->nilType);
 
-        TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().eqFamily, {leftType, rightType}, {}, scope, binary->location);
+        TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().eqFunc, {leftType, rightType}, {}, scope, binary->location);
         return Inference{resultType, std::move(refinement)};
     }
     case AstExprBinary::Op::Op__Count:
@@ -3160,14 +3160,14 @@ TypeId ConstraintGenerator::makeUnion(const ScopePtr& scope, Location location,
     if (get<NeverType>(follow(rhs)))
         return lhs;
 
-    TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().unionFamily, {lhs, rhs}, {}, scope, location);
+    TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().unionFunc, {lhs, rhs}, {}, scope, location);
 
     return resultType;
 }
 
 TypeId ConstraintGenerator::makeIntersect(const ScopePtr& scope, Location location, TypeId lhs, TypeId rhs)
 {
-    TypeId resultType = createTypeFamilyInstance(builtinTypeFunctions().intersectFamily, {lhs, rhs}, {}, scope, location);
+    TypeId resultType = createTypeFunctionInstance(builtinTypeFunctions().intersectFunc, {lhs, rhs}, {}, scope, location);
 
     return resultType;
 }
@@ -3285,7 +3285,7 @@ void ConstraintGenerator::fillInInferredBindings(const ScopePtr& globalScope, As
             scope->bindings[symbol] = Binding{tys.front(), location};
         else
         {
-            TypeId ty = createTypeFamilyInstance(builtinTypeFunctions().unionFamily, std::move(tys), {}, globalScope, location);
+            TypeId ty = createTypeFunctionInstance(builtinTypeFunctions().unionFunc, std::move(tys), {}, globalScope, location);
 
             scope->bindings[symbol] = Binding{ty, location};
         }
@@ -3355,10 +3355,10 @@ std::vector<std::optional<TypeId>> ConstraintGenerator::getExpectedCallTypesForF
     return expectedTypes;
 }
 
-TypeId ConstraintGenerator::createTypeFamilyInstance(
+TypeId ConstraintGenerator::createTypeFunctionInstance(
-    const TypeFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments, const ScopePtr& scope, Location location)
+    const TypeFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments, const ScopePtr& scope, Location location)
 {
-    TypeId result = arena->addTypeFamily(family, typeArguments, packArguments);
+    TypeId result = arena->addTypeFunction(family, typeArguments, packArguments);
     addConstraint(scope, location, ReduceConstraint{result});
     return result;
 }

Analysis/src/ConstraintSolver.cpp

@@ -18,7 +18,7 @@
 #include "Luau/TimeTrace.h"
 #include "Luau/ToString.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
@@ -298,7 +298,7 @@ struct InstantiationQueuer : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType&) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType&) override
     {
         solver->pushConstraint(scope, location, ReduceConstraint{ty});
         return true;
@@ -510,10 +510,10 @@ void ConstraintSolver::finalizeTypeFamilies()
     for (auto [t, constraint] : typeFamiliesToFinalize)
     {
         TypeId ty = follow(t);
-        if (get<TypeFamilyInstanceType>(ty))
+        if (get<TypeFunctionInstanceType>(ty))
         {
-            FamilyGraphReductionResult result =
+            FunctionGraphReductionResult result =
-                reduceFamilies(t, constraint->location, TypeFamilyContext{NotNull{this}, constraint->scope, NotNull{constraint}}, true);
+                reduceTypeFunctions(t, constraint->location, TypeFunctionContext{NotNull{this}, constraint->scope, NotNull{constraint}}, true);
 
             for (TypeId r : result.reducedTypes)
                 unblock(r, constraint->location);
@@ -1394,7 +1394,7 @@ bool ConstraintSolver::tryDispatch(const HasPropConstraint& c, NotNull<const Con
     LUAU_ASSERT(get<BlockedType>(resultType));
     LUAU_ASSERT(canMutate(resultType, constraint));
 
-    if (isBlocked(subjectType) || get<PendingExpansionType>(subjectType) || get<TypeFamilyInstanceType>(subjectType))
+    if (isBlocked(subjectType) || get<PendingExpansionType>(subjectType) || get<TypeFunctionInstanceType>(subjectType))
         return block(subjectType, constraint);
 
     if (const TableType* subjectTable = getTableType(subjectType))
@@ -1433,6 +1433,12 @@ bool ConstraintSolver::tryDispatchHasIndexer(
     LUAU_ASSERT(get<BlockedType>(resultType));
     LUAU_ASSERT(canMutate(resultType, constraint));
 
+    if (get<AnyType>(subjectType))
+    {
+        bind(constraint, resultType, builtinTypes->anyType);
+        return true;
+    }
+
     if (auto ft = get<FreeType>(subjectType))
     {
         if (auto tbl = get<TableType>(follow(ft->upperBound)); tbl && tbl->indexer)
@@ -1955,8 +1961,8 @@ bool ConstraintSolver::tryDispatch(const UnpackConstraint& c, NotNull<const Cons
 bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Constraint> constraint, bool force)
 {
     TypeId ty = follow(c.ty);
-    FamilyGraphReductionResult result =
+    FunctionGraphReductionResult result =
-        reduceFamilies(ty, constraint->location, TypeFamilyContext{NotNull{this}, constraint->scope, constraint}, force);
+        reduceTypeFunctions(ty, constraint->location, TypeFunctionContext{NotNull{this}, constraint->scope, constraint}, force);
 
     for (TypeId r : result.reducedTypes)
         unblock(r, constraint->location);
@@ -1967,8 +1973,8 @@ bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Cons
     bool reductionFinished = result.blockedTypes.empty() && result.blockedPacks.empty();
 
     ty = follow(ty);
-    // If we couldn't reduce this type family, stick it in the set!
+    // If we couldn't reduce this type function, stick it in the set!
-    if (get<TypeFamilyInstanceType>(ty))
+    if (get<TypeFunctionInstanceType>(ty))
         typeFamiliesToFinalize[ty] = constraint;
 
     if (force || reductionFinished)
@@ -1976,9 +1982,9 @@ bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Cons
         // if we're completely dispatching this constraint, we want to record any uninhabited type families to unblock.
         for (auto error : result.errors)
         {
-            if (auto utf = get<UninhabitedTypeFamily>(error))
+            if (auto utf = get<UninhabitedTypeFunction>(error))
                 uninhabitedTypeFamilies.insert(utf->ty);
-            else if (auto utpf = get<UninhabitedTypePackFamily>(error))
+            else if (auto utpf = get<UninhabitedTypePackFunction>(error))
                 uninhabitedTypeFamilies.insert(utpf->tp);
         }
     }
@@ -1998,8 +2004,8 @@ bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Cons
 bool ConstraintSolver::tryDispatch(const ReducePackConstraint& c, NotNull<const Constraint> constraint, bool force)
 {
     TypePackId tp = follow(c.tp);
-    FamilyGraphReductionResult result =
+    FunctionGraphReductionResult result =
-        reduceFamilies(tp, constraint->location, TypeFamilyContext{NotNull{this}, constraint->scope, constraint}, force);
+        reduceTypeFunctions(tp, constraint->location, TypeFunctionContext{NotNull{this}, constraint->scope, constraint}, force);
 
     for (TypeId r : result.reducedTypes)
         unblock(r, constraint->location);
@@ -2014,9 +2020,9 @@ bool ConstraintSolver::tryDispatch(const ReducePackConstraint& c, NotNull<const
         // if we're completely dispatching this constraint, we want to record any uninhabited type families to unblock.
         for (auto error : result.errors)
         {
-            if (auto utf = get<UninhabitedTypeFamily>(error))
+            if (auto utf = get<UninhabitedTypeFunction>(error))
                 uninhabitedTypeFamilies.insert(utf->ty);
-            else if (auto utpf = get<UninhabitedTypePackFamily>(error))
+            else if (auto utpf = get<UninhabitedTypePackFunction>(error))
                 uninhabitedTypeFamilies.insert(utpf->tp);
         }
     }
@@ -2103,7 +2109,7 @@ bool ConstraintSolver::tryDispatchIterableTable(TypeId iteratorTy, const Iterabl
          * it's possible that there are other constraints on the table that will
          * clarify what we should do.
          *
-         * We should eventually introduce a type family to talk about iteration.
+         * We should eventually introduce a type function to talk about iteration.
          */
         if (iteratorTable->state == TableState::Free && !force)
             return block(iteratorTy, constraint);
@@ -2713,13 +2719,13 @@ void ConstraintSolver::reproduceConstraints(NotNull<Scope> scope, const Location
 {
     for (auto [_, newTy] : subst.newTypes)
     {
-        if (get<TypeFamilyInstanceType>(newTy))
+        if (get<TypeFunctionInstanceType>(newTy))
             pushConstraint(scope, location, ReduceConstraint{newTy});
     }
 
     for (auto [_, newPack] : subst.newPacks)
     {
-        if (get<TypeFamilyInstanceTypePack>(newPack))
+        if (get<TypeFunctionInstanceTypePack>(newPack))
             pushConstraint(scope, location, ReducePackConstraint{newPack});
     }
 }
@@ -2728,7 +2734,7 @@ bool ConstraintSolver::isBlocked(TypeId ty)
 {
     ty = follow(ty);
 
-    if (auto tfit = get<TypeFamilyInstanceType>(ty))
+    if (auto tfit = get<TypeFunctionInstanceType>(ty))
         return uninhabitedTypeFamilies.contains(ty) == false;
 
     return nullptr != get<BlockedType>(ty) || nullptr != get<PendingExpansionType>(ty);
@@ -2738,7 +2744,7 @@ bool ConstraintSolver::isBlocked(TypePackId tp)
 {
     tp = follow(tp);
 
-    if (auto tfitp = get<TypeFamilyInstanceTypePack>(tp))
+    if (auto tfitp = get<TypeFunctionInstanceTypePack>(tp))
         return uninhabitedTypeFamilies.contains(tp) == false;
 
     return nullptr != get<BlockedTypePack>(tp);

Analysis/src/Error.cpp

@@ -8,7 +8,7 @@
 #include "Luau/StringUtils.h"
 #include "Luau/ToString.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 
 #include <optional>
 #include <stdexcept>
@@ -64,16 +64,16 @@ static std::string wrongNumberOfArgsString(
 namespace Luau
 {
 
-// this list of binary operator type families is used for better stringification of type families errors
+// this list of binary operator type functions is used for better stringification of type functions errors
 static const std::unordered_map<std::string, const char*> kBinaryOps{{"add", "+"}, {"sub", "-"}, {"mul", "*"}, {"div", "/"}, {"idiv", "//"},
     {"pow", "^"}, {"mod", "%"}, {"concat", ".."}, {"and", "and"}, {"or", "or"}, {"lt", "< or >="}, {"le", "<= or >"}, {"eq", "== or ~="}};
 
-// this list of unary operator type families is used for better stringification of type families errors
+// this list of unary operator type functions is used for better stringification of type functions errors
 static const std::unordered_map<std::string, const char*> kUnaryOps{{"unm", "-"}, {"len", "#"}, {"not", "not"}};
 
-// this list of type families will receive a special error indicating that the user should file a bug on the GitHub repository
+// this list of type functions will receive a special error indicating that the user should file a bug on the GitHub repository
-// putting a type family in this list indicates that it is expected to _always_ reduce
+// putting a type function in this list indicates that it is expected to _always_ reduce
-static const std::unordered_set<std::string> kUnreachableTypeFamilies{"refine", "singleton", "union", "intersect"};
+static const std::unordered_set<std::string> kUnreachableTypeFunctions{"refine", "singleton", "union", "intersect"};
 
 struct ErrorConverter
 {
@@ -577,12 +577,12 @@ struct ErrorConverter
         return "Attempting a dynamic property access on type '" + Luau::toString(e.ty) + "' is unsafe and may cause exceptions at runtime";
     }
 
-    std::string operator()(const UninhabitedTypeFamily& e) const
+    std::string operator()(const UninhabitedTypeFunction& e) const
     {
-        auto tfit = get<TypeFamilyInstanceType>(e.ty);
+        auto tfit = get<TypeFunctionInstanceType>(e.ty);
-        LUAU_ASSERT(tfit); // Luau analysis has actually done something wrong if this type is not a type family.
+        LUAU_ASSERT(tfit); // Luau analysis has actually done something wrong if this type is not a type function.
         if (!tfit)
-            return "Unexpected type " + Luau::toString(e.ty) + " flagged as an uninhabited type family.";
+            return "Unexpected type " + Luau::toString(e.ty) + " flagged as an uninhabited type function.";
 
         // unary operators
         if (auto unaryString = kUnaryOps.find(tfit->family->name); unaryString != kUnaryOps.end())
@@ -658,13 +658,13 @@ struct ErrorConverter
             if (tfit->typeArguments.size() == 1 && tfit->packArguments.empty())
                 return "Type '" + toString(tfit->typeArguments[0]) + "' does not have keys, so '" + Luau::toString(e.ty) + "' is invalid";
             else
-                return "Type family instance " + Luau::toString(e.ty) + " is ill-formed, and thus invalid";
+                return "Type function instance " + Luau::toString(e.ty) + " is ill-formed, and thus invalid";
         }
 
         if ("index" == tfit->family->name || "rawget" == tfit->family->name)
         {
             if (tfit->typeArguments.size() != 2)
-                return "Type family instance " + Luau::toString(e.ty) + " is ill-formed, and thus invalid";
+                return "Type function instance " + Luau::toString(e.ty) + " is ill-formed, and thus invalid";
 
             if (auto errType = get<ErrorType>(tfit->typeArguments[1])) // Second argument to (index | rawget)<_,_> is not a type
                 return "Second argument to " + tfit->family->name + "<" + Luau::toString(tfit->typeArguments[0]) + ", _> is not a valid index type";
@@ -673,15 +673,15 @@ struct ErrorConverter
                        "'";
         }
 
-        if (kUnreachableTypeFamilies.count(tfit->family->name))
+        if (kUnreachableTypeFunctions.count(tfit->family->name))
         {
-            return "Type family instance " + Luau::toString(e.ty) + " is uninhabited\n" +
+            return "Type function instance " + Luau::toString(e.ty) + " is uninhabited\n" +
                    "This is likely to be a bug, please report it at https://github.com/luau-lang/luau/issues";
         }
 
-        // Everything should be specialized above to report a more descriptive error that hopefully does not mention "type families" explicitly.
+        // Everything should be specialized above to report a more descriptive error that hopefully does not mention "type functions" explicitly.
         // If we produce this message, it's an indication that we've missed a specialization and it should be fixed!
-        return "Type family instance " + Luau::toString(e.ty) + " is uninhabited";
+        return "Type function instance " + Luau::toString(e.ty) + " is uninhabited";
     }
 
     std::string operator()(const ExplicitFunctionAnnotationRecommended& r) const
@@ -704,14 +704,14 @@ struct ErrorConverter
         return "Consider placing the following annotations on the arguments: " + argAnnotations + " or instead annotating the return as " + toReturn;
     }
 
-    std::string operator()(const UninhabitedTypePackFamily& e) const
+    std::string operator()(const UninhabitedTypePackFunction& e) const
     {
         return "Type pack family instance " + Luau::toString(e.tp) + " is uninhabited";
     }
 
     std::string operator()(const WhereClauseNeeded& e) const
     {
-        return "Type family instance " + Luau::toString(e.ty) +
+        return "Type function instance " + Luau::toString(e.ty) +
                " depends on generic function parameters but does not appear in the function signature; this construct cannot be type-checked at this "
                "time";
     }
@@ -1092,7 +1092,7 @@ bool DynamicPropertyLookupOnClassesUnsafe::operator==(const DynamicPropertyLooku
     return ty == rhs.ty;
 }
 
-bool UninhabitedTypeFamily::operator==(const UninhabitedTypeFamily& rhs) const
+bool UninhabitedTypeFunction::operator==(const UninhabitedTypeFunction& rhs) const
 {
     return ty == rhs.ty;
 }
@@ -1103,7 +1103,7 @@ bool ExplicitFunctionAnnotationRecommended::operator==(const ExplicitFunctionAnn
     return recommendedReturn == rhs.recommendedReturn && recommendedArgs == rhs.recommendedArgs;
 }
 
-bool UninhabitedTypePackFamily::operator==(const UninhabitedTypePackFamily& rhs) const
+bool UninhabitedTypePackFunction::operator==(const UninhabitedTypePackFunction& rhs) const
 {
     return tp == rhs.tp;
 }
@@ -1316,7 +1316,7 @@ void copyError(T& e, TypeArena& destArena, CloneState& cloneState)
     }
     else if constexpr (std::is_same_v<T, DynamicPropertyLookupOnClassesUnsafe>)
         e.ty = clone(e.ty);
-    else if constexpr (std::is_same_v<T, UninhabitedTypeFamily>)
+    else if constexpr (std::is_same_v<T, UninhabitedTypeFunction>)
         e.ty = clone(e.ty);
     else if constexpr (std::is_same_v<T, ExplicitFunctionAnnotationRecommended>)
     {
@@ -1324,7 +1324,7 @@ void copyError(T& e, TypeArena& destArena, CloneState& cloneState)
         for (auto& [_, t] : e.recommendedArgs)
             t = clone(t);
     }
-    else if constexpr (std::is_same_v<T, UninhabitedTypePackFamily>)
+    else if constexpr (std::is_same_v<T, UninhabitedTypePackFunction>)
         e.tp = clone(e.tp);
     else if constexpr (std::is_same_v<T, WhereClauseNeeded>)
         e.ty = clone(e.ty);

Analysis/src/Frontend.cpp

@@ -131,9 +131,10 @@ static ParseResult parseSourceForModule(std::string_view source, Luau::SourceMod
 
     if (FFlag::LuauStoreCommentsForDefinitionFiles && options.captureComments)
     {
-        sourceModule.hotcomments = std::move(parseResult.hotcomments);
+        sourceModule.hotcomments = parseResult.hotcomments;
-        sourceModule.commentLocations = std::move(parseResult.commentLocations);
+        sourceModule.commentLocations = parseResult.commentLocations;
     }
+
     return parseResult;
 }
 
@@ -1236,7 +1237,7 @@ struct InternalTypeFinder : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypePackId, const TypeFamilyInstanceTypePack&) override
+    bool visit(TypePackId, const TypeFunctionInstanceTypePack&) override
     {
         LUAU_ASSERT(false);
         return false;

Analysis/src/Generalization.cpp

@@ -804,7 +804,7 @@ struct TypeCacher : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType& tfit) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType& tfit) override
     {
         if (isCached(ty) || isUncacheable(ty))
             return false;
@@ -860,7 +860,7 @@ struct TypeCacher : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypePackId tp, const TypeFamilyInstanceTypePack&) override
+    bool visit(TypePackId tp, const TypeFunctionInstanceTypePack&) override
     {
         markUncacheable(tp);
         return false;

Analysis/src/IostreamHelpers.cpp

@@ -193,8 +193,8 @@ static void errorToString(std::ostream& stream, const T& err)
         stream << "TypePackMismatch { wanted = '" + toString(err.wantedTp) + "', given = '" + toString(err.givenTp) + "' }";
     else if constexpr (std::is_same_v<T, DynamicPropertyLookupOnClassesUnsafe>)
         stream << "DynamicPropertyLookupOnClassesUnsafe { " << toString(err.ty) << " }";
-    else if constexpr (std::is_same_v<T, UninhabitedTypeFamily>)
+    else if constexpr (std::is_same_v<T, UninhabitedTypeFunction>)
-        stream << "UninhabitedTypeFamily { " << toString(err.ty) << " }";
+        stream << "UninhabitedTypeFunction { " << toString(err.ty) << " }";
     else if constexpr (std::is_same_v<T, ExplicitFunctionAnnotationRecommended>)
     {
         std::string recArgs = "[";
@@ -204,8 +204,8 @@ static void errorToString(std::ostream& stream, const T& err)
         stream << "ExplicitFunctionAnnotationRecommended { recommmendedReturn = '" + toString(err.recommendedReturn) +
                       "', recommmendedArgs = " + recArgs + "}";
     }
-    else if constexpr (std::is_same_v<T, UninhabitedTypePackFamily>)
+    else if constexpr (std::is_same_v<T, UninhabitedTypePackFunction>)
-        stream << "UninhabitedTypePackFamily { " << toString(err.tp) << " }";
+        stream << "UninhabitedTypePackFunction { " << toString(err.tp) << " }";
     else if constexpr (std::is_same_v<T, WhereClauseNeeded>)
         stream << "WhereClauseNeeded { " << toString(err.ty) << " }";
     else if constexpr (std::is_same_v<T, PackWhereClauseNeeded>)

Analysis/src/Module.cpp

@@ -15,6 +15,7 @@
 #include <algorithm>
 
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
+LUAU_FASTFLAGVARIABLE(LuauSkipEmptyInstantiations, false);
 
 namespace Luau
 {
@@ -115,9 +116,22 @@ struct ClonePublicInterface : Substitution
         TypeId result = clone(ty);
 
         if (FunctionType* ftv = getMutable<FunctionType>(result))
+        {
+            if (FFlag::LuauSkipEmptyInstantiations && ftv->generics.empty() && ftv->genericPacks.empty())
+            {
+                GenericTypeFinder marker;
+                marker.traverse(result);
+
+                if (!marker.found)
+                    ftv->hasNoFreeOrGenericTypes = true;
+            }
+
             ftv->level = TypeLevel{0, 0};
+        }
         else if (TableType* ttv = getMutable<TableType>(result))
+        {
             ttv->level = TypeLevel{0, 0};
+        }
 
         return result;
     }

Analysis/src/NonStrictTypeChecker.cpp

@@ -10,7 +10,7 @@
 #include "Luau/Normalize.h"
 #include "Luau/Error.h"
 #include "Luau/TypeArena.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/Def.h"
 #include "Luau/ToString.h"
 #include "Luau/TypeFwd.h"
@@ -153,7 +153,7 @@ struct NonStrictTypeChecker
     Normalizer normalizer;
     Subtyping subtyping;
     NotNull<const DataFlowGraph> dfg;
-    DenseHashSet<TypeId> noTypeFamilyErrors{nullptr};
+    DenseHashSet<TypeId> noTypeFunctionErrors{nullptr};
     std::vector<NotNull<Scope>> stack;
     DenseHashMap<TypeId, TypeId> cachedNegations{nullptr};
 
@@ -208,14 +208,14 @@ struct NonStrictTypeChecker
 
     TypeId checkForFamilyInhabitance(TypeId instance, Location location)
     {
-        if (noTypeFamilyErrors.find(instance))
+        if (noTypeFunctionErrors.find(instance))
             return instance;
 
         ErrorVec errors =
-            reduceFamilies(instance, location, TypeFamilyContext{arena, builtinTypes, stack.back(), NotNull{&normalizer}, ice, limits}, true).errors;
+            reduceTypeFunctions(instance, location, TypeFunctionContext{arena, builtinTypes, stack.back(), NotNull{&normalizer}, ice, limits}, true).errors;
 
         if (errors.empty())
-            noTypeFamilyErrors.insert(instance);
+            noTypeFunctionErrors.insert(instance);
         // TODO??
         // if (!isErrorSuppressing(location, instance))
         //     reportErrors(std::move(errors));

Analysis/src/Normalize.cpp

@@ -816,7 +816,7 @@ static bool areNormalizedClasses(const NormalizedClassType& tys)
 
 static bool isPlainTyvar(TypeId ty)
 {
-    return (get<FreeType>(ty) || get<GenericType>(ty) || get<BlockedType>(ty) || get<PendingExpansionType>(ty) || get<TypeFamilyInstanceType>(ty));
+    return (get<FreeType>(ty) || get<GenericType>(ty) || get<BlockedType>(ty) || get<PendingExpansionType>(ty) || get<TypeFunctionInstanceType>(ty));
 }
 
 static bool isNormalizedTyvar(const NormalizedTyvars& tyvars)
@@ -883,7 +883,7 @@ static bool isCacheable(TypePackId tp, Set<TypeId>& seen)
 
     if (auto tail = it.tail())
     {
-        if (get<FreeTypePack>(*tail) || get<BlockedTypePack>(*tail) || get<TypeFamilyInstanceTypePack>(*tail))
+        if (get<FreeTypePack>(*tail) || get<BlockedTypePack>(*tail) || get<TypeFunctionInstanceTypePack>(*tail))
             return false;
     }
 
@@ -901,7 +901,7 @@ static bool isCacheable(TypeId ty, Set<TypeId>& seen)
     if (get<FreeType>(ty) || get<BlockedType>(ty) || get<PendingExpansionType>(ty))
         return false;
 
-    if (auto tfi = get<TypeFamilyInstanceType>(ty))
+    if (auto tfi = get<TypeFunctionInstanceType>(ty))
     {
         for (TypeId t : tfi->typeArguments)
         {
@@ -1795,7 +1795,7 @@ NormalizationResult Normalizer::unionNormalWithTy(NormalizedType& here, TypeId t
     else if (get<UnknownType>(here.tops))
         return NormalizationResult::True;
     else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) ||
-             get<TypeFamilyInstanceType>(there))
+             get<TypeFunctionInstanceType>(there))
     {
         if (tyvarIndex(there) <= ignoreSmallerTyvars)
             return NormalizationResult::True;
@@ -1872,7 +1872,7 @@ NormalizationResult Normalizer::unionNormalWithTy(NormalizedType& here, TypeId t
         if (res != NormalizationResult::True)
             return res;
     }
-    else if (get<PendingExpansionType>(there) || get<TypeFamilyInstanceType>(there))
+    else if (get<PendingExpansionType>(there) || get<TypeFunctionInstanceType>(there))
     {
         // nothing
     }
@@ -3080,7 +3080,7 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
         return NormalizationResult::True;
     }
     else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) ||
-             get<TypeFamilyInstanceType>(there))
+             get<TypeFunctionInstanceType>(there))
     {
         NormalizedType thereNorm{builtinTypes};
         NormalizedType topNorm{builtinTypes};

Analysis/src/OverloadResolution.cpp

@@ -5,7 +5,7 @@
 #include "Luau/Subtyping.h"
 #include "Luau/TxnLog.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
@@ -175,14 +175,15 @@ bool OverloadResolver::isLiteral(AstExpr* expr)
 std::pair<OverloadResolver::Analysis, ErrorVec> OverloadResolver::checkOverload_(
     TypeId fnTy, const FunctionType* fn, const TypePack* args, AstExpr* fnExpr, const std::vector<AstExpr*>* argExprs)
 {
-    FamilyGraphReductionResult result =
+    FunctionGraphReductionResult result =
-        reduceFamilies(fnTy, callLoc, TypeFamilyContext{arena, builtinTypes, scope, normalizer, ice, limits}, /*force=*/true);
+        reduceTypeFunctions(fnTy, callLoc, TypeFunctionContext{arena, builtinTypes, scope, normalizer, ice, limits}, /*force=*/true);
     if (!result.errors.empty())
         return {OverloadIsNonviable, result.errors};
 
     ErrorVec argumentErrors;
+    TypePackId typ = arena->addTypePack(*args);
 
-    TypeId prospectiveFunction = arena->addType(FunctionType{arena->addTypePack(*args), builtinTypes->anyTypePack});
+    TypeId prospectiveFunction = arena->addType(FunctionType{typ, builtinTypes->anyTypePack});
     SubtypingResult sr = subtyping.isSubtype(fnTy, prospectiveFunction);
 
     if (sr.isSubtype)
@@ -253,7 +254,14 @@ std::pair<OverloadResolver::Analysis, ErrorVec> OverloadResolver::checkOverload_
         if (const Luau::TypePath::Index* pathIndexComponent = get_if<Luau::TypePath::Index>(&reason.superPath.components.at(1)))
         {
             size_t nthArgument = pathIndexComponent->index;
-            argLocation = argExprs->at(nthArgument)->location;
+            // if the nth type argument to the function is less than the number of ast expressions we passed to the function
+            // we should be able to pull out the location of the argument
+            // If the nth type argument to the function is out of range of the ast expressions we passed to the function
+            // e.g. table.pack(functionThatReturnsMultipleArguments(arg1, arg2, ....)), default to the location of the last passed expression
+            // If we passed no expression arguments to the call, default to the location of the function expression.
+            argLocation = nthArgument < argExprs->size() ? argExprs->at(nthArgument)->location
+                          : argExprs->size() != 0        ? argExprs->back()->location
+                                                         : fnExpr->location;
 
             std::optional<TypeId> failedSubTy = traverseForType(fnTy, reason.subPath, builtinTypes);
             std::optional<TypeId> failedSuperTy = traverseForType(prospectiveFunction, reason.superPath, builtinTypes);

Analysis/src/Substitution.cpp

@@ -125,9 +125,9 @@ static TypeId shallowClone(TypeId ty, TypeArena& dest, const TxnLog* log, bool a
         }
         else if constexpr (std::is_same_v<T, NegationType>)
             return dest.addType(NegationType{a.ty});
-        else if constexpr (std::is_same_v<T, TypeFamilyInstanceType>)
+        else if constexpr (std::is_same_v<T, TypeFunctionInstanceType>)
         {
-            TypeFamilyInstanceType clone{a.family, a.typeArguments, a.packArguments};
+            TypeFunctionInstanceType clone{a.family, a.typeArguments, a.packArguments};
             return dest.addType(std::move(clone));
         }
         else
@@ -226,7 +226,7 @@ void Tarjan::visitChildren(TypeId ty, int index)
         for (TypePackId a : petv->packArguments)
             visitChild(a);
     }
-    else if (const TypeFamilyInstanceType* tfit = get<TypeFamilyInstanceType>(ty))
+    else if (const TypeFunctionInstanceType* tfit = get<TypeFunctionInstanceType>(ty))
     {
         for (TypeId a : tfit->typeArguments)
             visitChild(a);
@@ -669,9 +669,9 @@ TypePackId Substitution::clone(TypePackId tp)
         clone.hidden = vtp->hidden;
         return addTypePack(std::move(clone));
     }
-    else if (const TypeFamilyInstanceTypePack* tfitp = get<TypeFamilyInstanceTypePack>(tp))
+    else if (const TypeFunctionInstanceTypePack* tfitp = get<TypeFunctionInstanceTypePack>(tp))
     {
-        TypeFamilyInstanceTypePack clone{
+        TypeFunctionInstanceTypePack clone{
             tfitp->family, std::vector<TypeId>(tfitp->typeArguments.size()), std::vector<TypePackId>(tfitp->packArguments.size())};
         clone.typeArguments.assign(tfitp->typeArguments.begin(), tfitp->typeArguments.end());
         clone.packArguments.assign(tfitp->packArguments.begin(), tfitp->packArguments.end());
@@ -798,7 +798,7 @@ void Substitution::replaceChildren(TypeId ty)
         for (TypePackId& a : petv->packArguments)
             a = replace(a);
     }
-    else if (TypeFamilyInstanceType* tfit = getMutable<TypeFamilyInstanceType>(ty))
+    else if (TypeFunctionInstanceType* tfit = getMutable<TypeFunctionInstanceType>(ty))
     {
         for (TypeId& a : tfit->typeArguments)
             a = replace(a);
@@ -850,7 +850,7 @@ void Substitution::replaceChildren(TypePackId tp)
     {
         vtp->ty = replace(vtp->ty);
     }
-    else if (TypeFamilyInstanceTypePack* tfitp = getMutable<TypeFamilyInstanceTypePack>(tp))
+    else if (TypeFunctionInstanceTypePack* tfitp = getMutable<TypeFunctionInstanceTypePack>(tp))
     {
         for (TypeId& t : tfitp->typeArguments)
             t = replace(t);

Analysis/src/Subtyping.cpp

@@ -13,7 +13,7 @@
 #include "Luau/Type.h"
 #include "Luau/TypeArena.h"
 #include "Luau/TypeCheckLimits.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypePath.h"
 #include "Luau/TypeUtils.h"
@@ -121,9 +121,9 @@ SubtypingResult& SubtypingResult::andAlso(const SubtypingResult& other)
 {
     // If the other result is not a subtype, we want to join all of its
     // reasonings to this one. If this result already has reasonings of its own,
-    // those need to be attributed here.
+    // those need to be attributed here whenever this _also_ failed.
     if (!other.isSubtype)
-        reasoning = mergeReasonings(reasoning, other.reasoning);
+        reasoning = isSubtype ? std::move(other.reasoning) : mergeReasonings(reasoning, other.reasoning);
 
     isSubtype &= other.isSubtype;
     normalizationTooComplex |= other.normalizationTooComplex;
@@ -579,19 +579,19 @@ SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, TypeId sub
             }
         }
     }
-    else if (auto subTypeFamilyInstance = get<TypeFamilyInstanceType>(subTy))
+    else if (auto subTypeFunctionInstance = get<TypeFunctionInstanceType>(subTy))
     {
         if (auto substSubTy = env.applyMappedGenerics(builtinTypes, arena, subTy))
-            subTypeFamilyInstance = get<TypeFamilyInstanceType>(*substSubTy);
+            subTypeFunctionInstance = get<TypeFunctionInstanceType>(*substSubTy);
 
-        result = isCovariantWith(env, subTypeFamilyInstance, superTy);
+        result = isCovariantWith(env, subTypeFunctionInstance, superTy);
     }
-    else if (auto superTypeFamilyInstance = get<TypeFamilyInstanceType>(superTy))
+    else if (auto superTypeFunctionInstance = get<TypeFunctionInstanceType>(superTy))
     {
         if (auto substSuperTy = env.applyMappedGenerics(builtinTypes, arena, superTy))
-            superTypeFamilyInstance = get<TypeFamilyInstanceType>(*substSuperTy);
+            superTypeFunctionInstance = get<TypeFunctionInstanceType>(*substSuperTy);
 
-        result = isCovariantWith(env, subTy, superTypeFamilyInstance);
+        result = isCovariantWith(env, subTy, superTypeFunctionInstance);
     }
     else if (auto subGeneric = get<GenericType>(subTy); subGeneric && variance == Variance::Covariant)
     {
@@ -1584,19 +1584,19 @@ bool Subtyping::bindGeneric(SubtypingEnvironment& env, TypeId subTy, TypeId supe
     return true;
 }
 
-SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, const TypeFamilyInstanceType* subFamilyInstance, const TypeId superTy)
+SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, const TypeFunctionInstanceType* subFamilyInstance, const TypeId superTy)
 {
-    // Reduce the typefamily instance
+    // Reduce the type function instance
-    auto [ty, errors] = handleTypeFamilyReductionResult(subFamilyInstance);
+    auto [ty, errors] = handleTypeFunctionReductionResult(subFamilyInstance);
 
-    // If we return optional, that means the type family was irreducible - we can reduce that to never
+    // If we return optional, that means the type function was irreducible - we can reduce that to never
     return isCovariantWith(env, ty, superTy).withErrors(errors).withSubComponent(TypePath::Reduction{ty});
 }
 
-SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, const TypeId subTy, const TypeFamilyInstanceType* superFamilyInstance)
+SubtypingResult Subtyping::isCovariantWith(SubtypingEnvironment& env, const TypeId subTy, const TypeFunctionInstanceType* superFamilyInstance)
 {
-    // Reduce the typefamily instance
+    // Reduce the type function instance
-    auto [ty, errors] = handleTypeFamilyReductionResult(superFamilyInstance);
+    auto [ty, errors] = handleTypeFunctionReductionResult(superFamilyInstance);
     return isCovariantWith(env, subTy, ty).withErrors(errors).withSuperComponent(TypePath::Reduction{ty});
 }
 
@@ -1632,15 +1632,15 @@ TypeId Subtyping::makeAggregateType(const Container& container, TypeId orElse)
         return arena->addType(T{std::vector<TypeId>(begin(container), end(container))});
 }
 
-std::pair<TypeId, ErrorVec> Subtyping::handleTypeFamilyReductionResult(const TypeFamilyInstanceType* familyInstance)
+std::pair<TypeId, ErrorVec> Subtyping::handleTypeFunctionReductionResult(const TypeFunctionInstanceType* familyInstance)
 {
-    TypeFamilyContext context{arena, builtinTypes, scope, normalizer, iceReporter, NotNull{&limits}};
+    TypeFunctionContext context{arena, builtinTypes, scope, normalizer, iceReporter, NotNull{&limits}};
     TypeId family = arena->addType(*familyInstance);
-    FamilyGraphReductionResult result = reduceFamilies(family, {}, context, true);
+    FunctionGraphReductionResult result = reduceTypeFunctions(family, {}, context, true);
     ErrorVec errors;
     if (result.blockedTypes.size() != 0 || result.blockedPacks.size() != 0)
     {
-        errors.push_back(TypeError{{}, UninhabitedTypeFamily{family}});
+        errors.push_back(TypeError{{}, UninhabitedTypeFunction{family}});
         return {builtinTypes->neverType, errors};
     }
     if (result.reducedTypes.contains(family))

Analysis/src/ToDot.cpp

@@ -4,7 +4,7 @@
 #include "Luau/ToString.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/StringUtils.h"
 
 #include <unordered_map>
@@ -343,9 +343,9 @@ void StateDot::visitChildren(TypeId ty, int index)
 
             visitChild(t.ty, index, "[negated]");
         }
-        else if constexpr (std::is_same_v<T, TypeFamilyInstanceType>)
+        else if constexpr (std::is_same_v<T, TypeFunctionInstanceType>)
         {
-            formatAppend(result, "TypeFamilyInstanceType %s %d", t.family->name.c_str(), index);
+            formatAppend(result, "TypeFunctionInstanceType %s %d", t.family->name.c_str(), index);
             finishNodeLabel(ty);
             finishNode();
 

Analysis/src/ToString.cpp

@@ -11,7 +11,7 @@
 #include "Luau/TypeInfer.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/VisitType.h"
 #include "Luau/TypeOrPack.h"
 
@@ -1031,7 +1031,7 @@ struct TypeStringifier
             state.emit(")");
     }
 
-    void operator()(TypeId, const TypeFamilyInstanceType& tfitv)
+    void operator()(TypeId, const TypeFunctionInstanceType& tfitv)
     {
         state.emit(tfitv.family->name);
         state.emit("<");
@@ -1232,7 +1232,7 @@ struct TypePackStringifier
         state.emit("*");
     }
 
-    void operator()(TypePackId, const TypeFamilyInstanceTypePack& tfitp)
+    void operator()(TypePackId, const TypeFunctionInstanceTypePack& tfitp)
     {
         state.emit(tfitp.family->name);
         state.emit("<");

Analysis/src/Type.cpp

@@ -9,7 +9,7 @@
 #include "Luau/RecursionCounter.h"
 #include "Luau/StringUtils.h"
 #include "Luau/ToString.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypePack.h"
 #include "Luau/VecDeque.h"
@@ -423,7 +423,7 @@ bool maybeSingleton(TypeId ty)
         for (TypeId part : itv)
             if (maybeSingleton(part)) // will i regret this?
                 return true;
-    if (const TypeFamilyInstanceType* tfit = get<TypeFamilyInstanceType>(ty))
+    if (const TypeFunctionInstanceType* tfit = get<TypeFunctionInstanceType>(ty))
         if (tfit->family->name == "keyof" || tfit->family->name == "rawkeyof")
             return true;
     return false;
@@ -1081,7 +1081,7 @@ void persist(TypeId ty)
         else if (get<GenericType>(t) || get<AnyType>(t) || get<FreeType>(t) || get<SingletonType>(t) || get<PrimitiveType>(t) || get<NegationType>(t))
         {
         }
-        else if (auto tfit = get<TypeFamilyInstanceType>(t))
+        else if (auto tfit = get<TypeFunctionInstanceType>(t))
         {
             for (auto ty : tfit->typeArguments)
                 queue.push_back(ty);
@@ -1117,7 +1117,7 @@ void persist(TypePackId tp)
     else if (get<GenericTypePack>(tp))
     {
     }
-    else if (auto tfitp = get<TypeFamilyInstanceTypePack>(tp))
+    else if (auto tfitp = get<TypeFunctionInstanceTypePack>(tp))
     {
         for (auto ty : tfitp->typeArguments)
             persist(ty);

Analysis/src/TypeArena.cpp

@@ -94,24 +94,24 @@ TypePackId TypeArena::addTypePack(TypePackVar tp)
     return allocated;
 }
 
-TypeId TypeArena::addTypeFamily(const TypeFamily& family, std::initializer_list<TypeId> types)
+TypeId TypeArena::addTypeFunction(const TypeFunction& family, std::initializer_list<TypeId> types)
 {
-    return addType(TypeFamilyInstanceType{family, std::move(types)});
+    return addType(TypeFunctionInstanceType{family, std::move(types)});
 }
 
-TypeId TypeArena::addTypeFamily(const TypeFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
+TypeId TypeArena::addTypeFunction(const TypeFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
 {
-    return addType(TypeFamilyInstanceType{family, std::move(typeArguments), std::move(packArguments)});
+    return addType(TypeFunctionInstanceType{family, std::move(typeArguments), std::move(packArguments)});
 }
 
-TypePackId TypeArena::addTypePackFamily(const TypePackFamily& family, std::initializer_list<TypeId> types)
+TypePackId TypeArena::addTypePackFunction(const TypePackFunction& family, std::initializer_list<TypeId> types)
 {
-    return addTypePack(TypeFamilyInstanceTypePack{NotNull{&family}, std::move(types)});
+    return addTypePack(TypeFunctionInstanceTypePack{NotNull{&family}, std::move(types)});
 }
 
-TypePackId TypeArena::addTypePackFamily(const TypePackFamily& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
+TypePackId TypeArena::addTypePackFunction(const TypePackFunction& family, std::vector<TypeId> typeArguments, std::vector<TypePackId> packArguments)
 {
-    return addTypePack(TypeFamilyInstanceTypePack{NotNull{&family}, std::move(typeArguments), std::move(packArguments)});
+    return addTypePack(TypeFunctionInstanceTypePack{NotNull{&family}, std::move(typeArguments), std::move(packArguments)});
 }
 
 void freeze(TypeArena& arena)

Analysis/src/TypeAttach.cpp

@@ -9,7 +9,7 @@
 #include "Luau/TypeInfer.h"
 #include "Luau/TypePack.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 
 #include <string>
 
@@ -380,7 +380,7 @@ public:
         // FIXME: do the same thing we do with ErrorType
         throw InternalCompilerError("Cannot convert NegationType into AstNode");
     }
-    AstType* operator()(const TypeFamilyInstanceType& tfit)
+    AstType* operator()(const TypeFunctionInstanceType& tfit)
     {
         return allocator->alloc<AstTypeReference>(Location(), std::nullopt, AstName{tfit.family->name.c_str()}, std::nullopt, Location());
     }
@@ -454,7 +454,7 @@ public:
         return allocator->alloc<AstTypePackGeneric>(Location(), AstName("Unifiable<Error>"));
     }
 
-    AstTypePack* operator()(const TypeFamilyInstanceTypePack& tfitp) const
+    AstTypePack* operator()(const TypeFunctionInstanceTypePack& tfitp) const
     {
         return allocator->alloc<AstTypePackGeneric>(Location(), AstName(tfitp.family->name.c_str()));
     }

Analysis/src/TypeChecker2.cpp

@@ -16,8 +16,8 @@
 #include "Luau/ToString.h"
 #include "Luau/TxnLog.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
-#include "Luau/TypeFamilyReductionGuesser.h"
+#include "Luau/TypeFunctionReductionGuesser.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypePath.h"
@@ -121,13 +121,13 @@ struct FamilyFinder : TypeOnceVisitor
     DenseHashSet<TypeId> mentionedFamilies{nullptr};
     DenseHashSet<TypePackId> mentionedFamilyPacks{nullptr};
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType&) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType&) override
     {
         mentionedFamilies.insert(ty);
         return true;
     }
 
-    bool visit(TypePackId tp, const TypeFamilyInstanceTypePack&) override
+    bool visit(TypePackId tp, const TypeFunctionInstanceTypePack&) override
     {
         mentionedFamilyPacks.insert(tp);
         return true;
@@ -151,7 +151,7 @@ struct InternalFamilyFinder : TypeOnceVisitor
         mentionedFamilyPacks = std::move(f.mentionedFamilyPacks);
     }
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType& tfit) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType& tfit) override
     {
         bool hasGeneric = false;
 
@@ -177,7 +177,7 @@ struct InternalFamilyFinder : TypeOnceVisitor
         {
             for (TypeId mentioned : mentionedFamilies)
             {
-                const TypeFamilyInstanceType* mentionedTfit = get<TypeFamilyInstanceType>(mentioned);
+                const TypeFunctionInstanceType* mentionedTfit = get<TypeFunctionInstanceType>(mentioned);
                 LUAU_ASSERT(mentionedTfit);
                 if (areEquivalent(tfit, *mentionedTfit))
                 {
@@ -191,7 +191,7 @@ struct InternalFamilyFinder : TypeOnceVisitor
         return true;
     }
 
-    bool visit(TypePackId tp, const TypeFamilyInstanceTypePack& tfitp) override
+    bool visit(TypePackId tp, const TypeFunctionInstanceTypePack& tfitp) override
     {
         bool hasGeneric = false;
 
@@ -217,7 +217,7 @@ struct InternalFamilyFinder : TypeOnceVisitor
         {
             for (TypePackId mentioned : mentionedFamilyPacks)
             {
-                const TypeFamilyInstanceTypePack* mentionedTfitp = get<TypeFamilyInstanceTypePack>(mentioned);
+                const TypeFunctionInstanceTypePack* mentionedTfitp = get<TypeFunctionInstanceTypePack>(mentioned);
                 LUAU_ASSERT(mentionedTfitp);
                 if (areEquivalent(tfitp, *mentionedTfitp))
                 {
@@ -245,7 +245,7 @@ struct TypeChecker2
     std::vector<NotNull<Scope>> stack;
     std::vector<TypeId> functionDeclStack;
 
-    DenseHashSet<TypeId> seenTypeFamilyInstances{nullptr};
+    DenseHashSet<TypeId> seenTypeFunctionInstances{nullptr};
 
     Normalizer normalizer;
     Subtyping _subtyping;
@@ -437,12 +437,12 @@ struct TypeChecker2
 
     TypeId checkForFamilyInhabitance(TypeId instance, Location location)
     {
-        if (seenTypeFamilyInstances.find(instance))
+        if (seenTypeFunctionInstances.find(instance))
             return instance;
-        seenTypeFamilyInstances.insert(instance);
+        seenTypeFunctionInstances.insert(instance);
 
-        ErrorVec errors = reduceFamilies(instance, location,
+        ErrorVec errors = reduceTypeFunctions(instance, location,
-            TypeFamilyContext{NotNull{&module->internalTypes}, builtinTypes, stack.back(), NotNull{&normalizer}, ice, limits}, true)
+            TypeFunctionContext{NotNull{&module->internalTypes}, builtinTypes, stack.back(), NotNull{&normalizer}, ice, limits}, true)
                               .errors;
         if (!isErrorSuppressing(location, instance))
             reportErrors(std::move(errors));
@@ -1731,12 +1731,12 @@ struct TypeChecker2
             const FunctionType* inferredFtv = get<FunctionType>(normalizedFnTy->functions.parts.front());
             LUAU_ASSERT(inferredFtv);
 
-            TypeFamilyReductionGuesser guesser{NotNull{&module->internalTypes}, builtinTypes, NotNull{&normalizer}};
+            TypeFunctionReductionGuesser guesser{NotNull{&module->internalTypes}, builtinTypes, NotNull{&normalizer}};
             for (TypeId retTy : inferredFtv->retTypes)
             {
-                if (get<TypeFamilyInstanceType>(follow(retTy)))
+                if (get<TypeFunctionInstanceType>(follow(retTy)))
                 {
-                    TypeFamilyReductionGuessResult result = guesser.guessTypeFamilyReductionForFunction(*fn, inferredFtv, retTy);
+                    TypeFunctionReductionGuessResult result = guesser.guessTypeFunctionReductionForFunctionExpr(*fn, inferredFtv, retTy);
                     if (result.shouldRecommendAnnotation)
                         reportError(ExplicitFunctionAnnotationRecommended{std::move(result.guessedFunctionAnnotations), result.guessedReturnType},
                             fn->location);
@@ -1853,7 +1853,7 @@ struct TypeChecker2
         TypeId rightType = follow(lookupType(expr->right));
         TypeId expectedResult = follow(lookupType(expr));
 
-        if (get<TypeFamilyInstanceType>(expectedResult))
+        if (get<TypeFunctionInstanceType>(expectedResult))
         {
             checkForInternalFamily(expectedResult, expr->location);
             return expectedResult;
@@ -1954,7 +1954,7 @@ struct TypeChecker2
                 if (!selectedOverloadTy)
                 {
                     // reportError(CodeTooComplex{}, expr->location);
-                    // was handled by a type family
+                    // was handled by a type function
                     return expectedResult;
                 }
 

Analysis/src/TypeFunction.cpp

@@ -1,6 +1,6 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 
 #include "Luau/Common.h"
 #include "Luau/ConstraintSolver.h"
@@ -15,7 +15,7 @@
 #include "Luau/ToString.h"
 #include "Luau/TxnLog.h"
 #include "Luau/Type.h"
-#include "Luau/TypeFamilyReductionGuesser.h"
+#include "Luau/TypeFunctionReductionGuesser.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
@@ -24,10 +24,10 @@
 
 #include <iterator>
 
-// used to control emitting CodeTooComplex warnings on type family reduction
+// used to control emitting CodeTooComplex warnings on type function reduction
 LUAU_DYNAMIC_FASTINTVARIABLE(LuauTypeFamilyGraphReductionMaximumSteps, 1'000'000);
 
-// used to control the limits of type family application over union type arguments
+// used to control the limits of type function application over union type arguments
 // e.g. `mul<a | b, c | d>` blows up into `mul<a, c> | mul<a, d> | mul<b, c> | mul<b, d>`
 LUAU_DYNAMIC_FASTINTVARIABLE(LuauTypeFamilyApplicationCartesianProductLimit, 5'000);
 
@@ -49,7 +49,7 @@ struct InstanceCollector : TypeOnceVisitor
     TypeOrTypePackIdSet shouldGuess{nullptr};
     std::vector<TypeId> cyclicInstance;
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType&) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType&) override
     {
         // TypeOnceVisitor performs a depth-first traversal in the absence of
         // cycles. This means that by pushing to the front of the queue, we will
@@ -58,7 +58,7 @@ struct InstanceCollector : TypeOnceVisitor
         // we want to reduce the innermost Add<number, number> instantiation
         // first.
 
-        if (DFInt::LuauTypeFamilyUseGuesserDepth >= 0 && typeFamilyDepth > DFInt::LuauTypeFamilyUseGuesserDepth)
+        if (DFInt::LuauTypeFamilyUseGuesserDepth >= 0 && typeFunctionDepth > DFInt::LuauTypeFamilyUseGuesserDepth)
             shouldGuess.insert(ty);
 
         tys.push_front(ty);
@@ -70,7 +70,7 @@ struct InstanceCollector : TypeOnceVisitor
     {
         /// Detected cyclic type pack
         TypeId t = follow(ty);
-        if (get<TypeFamilyInstanceType>(t))
+        if (get<TypeFunctionInstanceType>(t))
             cyclicInstance.push_back(t);
     }
 
@@ -79,7 +79,7 @@ struct InstanceCollector : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypePackId tp, const TypeFamilyInstanceTypePack&) override
+    bool visit(TypePackId tp, const TypeFunctionInstanceTypePack&) override
     {
         // TypeOnceVisitor performs a depth-first traversal in the absence of
         // cycles. This means that by pushing to the front of the queue, we will
@@ -88,7 +88,7 @@ struct InstanceCollector : TypeOnceVisitor
         // we want to reduce the innermost Add<number, number> instantiation
         // first.
 
-        if (DFInt::LuauTypeFamilyUseGuesserDepth >= 0 && typeFamilyDepth > DFInt::LuauTypeFamilyUseGuesserDepth)
+        if (DFInt::LuauTypeFamilyUseGuesserDepth >= 0 && typeFunctionDepth > DFInt::LuauTypeFamilyUseGuesserDepth)
             shouldGuess.insert(tp);
 
         tps.push_front(tp);
@@ -97,23 +97,23 @@ struct InstanceCollector : TypeOnceVisitor
     }
 };
 
-struct FamilyReducer
+struct TypeFunctionReducer
 {
-    TypeFamilyContext ctx;
+    TypeFunctionContext ctx;
 
     VecDeque<TypeId> queuedTys;
     VecDeque<TypePackId> queuedTps;
     TypeOrTypePackIdSet shouldGuess;
     std::vector<TypeId> cyclicTypeFamilies;
     TypeOrTypePackIdSet irreducible{nullptr};
-    FamilyGraphReductionResult result;
+    FunctionGraphReductionResult result;
     bool force = false;
 
     // Local to the constraint being reduced.
     Location location;
 
-    FamilyReducer(VecDeque<TypeId> queuedTys, VecDeque<TypePackId> queuedTps, TypeOrTypePackIdSet shouldGuess, std::vector<TypeId> cyclicTypes,
+    TypeFunctionReducer(VecDeque<TypeId> queuedTys, VecDeque<TypePackId> queuedTps, TypeOrTypePackIdSet shouldGuess, std::vector<TypeId> cyclicTypes,
-        Location location, TypeFamilyContext ctx, bool force = false)
+        Location location, TypeFunctionContext ctx, bool force = false)
         : ctx(ctx)
         , queuedTys(std::move(queuedTys))
         , queuedTps(std::move(queuedTps))
@@ -126,7 +126,7 @@ struct FamilyReducer
 
     enum class SkipTestResult
     {
-        CyclicTypeFamily,
+        CyclicTypeFunction,
         Irreducible,
         Defer,
         Okay,
@@ -136,12 +136,12 @@ struct FamilyReducer
     {
         ty = follow(ty);
 
-        if (is<TypeFamilyInstanceType>(ty))
+        if (is<TypeFunctionInstanceType>(ty))
         {
             for (auto t : cyclicTypeFamilies)
             {
                 if (ty == t)
-                    return SkipTestResult::CyclicTypeFamily;
+                    return SkipTestResult::CyclicTypeFunction;
             }
 
             if (!irreducible.contains(ty))
@@ -161,7 +161,7 @@ struct FamilyReducer
     {
         ty = follow(ty);
 
-        if (is<TypeFamilyInstanceTypePack>(ty))
+        if (is<TypeFunctionInstanceTypePack>(ty))
         {
             if (!irreducible.contains(ty))
                 return SkipTestResult::Defer;
@@ -181,7 +181,7 @@ struct FamilyReducer
     {
         if (subject->owningArena != ctx.arena.get())
         {
-            result.errors.emplace_back(location, InternalError{"Attempting to modify a type family instance from another arena"});
+            result.errors.emplace_back(location, InternalError{"Attempting to modify a type function instance from another arena"});
             return;
         }
 
@@ -197,7 +197,7 @@ struct FamilyReducer
     }
 
     template<typename T>
-    void handleFamilyReduction(T subject, TypeFamilyReductionResult<T> reduction)
+    void handleTypeFunctionReduction(T subject, TypeFunctionReductionResult<T> reduction)
     {
         if (reduction.result)
             replace(subject, *reduction.result);
@@ -211,9 +211,9 @@ struct FamilyReducer
                     printf("%s is uninhabited\n", toString(subject, {true}).c_str());
 
                 if constexpr (std::is_same_v<T, TypeId>)
-                    result.errors.push_back(TypeError{location, UninhabitedTypeFamily{subject}});
+                    result.errors.push_back(TypeError{location, UninhabitedTypeFunction{subject}});
                 else if constexpr (std::is_same_v<T, TypePackId>)
-                    result.errors.push_back(TypeError{location, UninhabitedTypePackFamily{subject}});
+                    result.errors.push_back(TypeError{location, UninhabitedTypePackFunction{subject}});
             }
             else if (!reduction.uninhabited && !force)
             {
@@ -301,7 +301,7 @@ struct FamilyReducer
             if (FFlag::DebugLuauLogTypeFamilies)
                 printf("Flagged %s for reduction with guesser.\n", toString(subject, {true}).c_str());
 
-            TypeFamilyReductionGuesser guesser{ctx.arena, ctx.builtins, ctx.normalizer};
+            TypeFunctionReductionGuesser guesser{ctx.arena, ctx.builtins, ctx.normalizer};
             auto guessed = guesser.guess(subject);
 
             if (guessed)
@@ -332,11 +332,11 @@ struct FamilyReducer
         if (FFlag::DebugLuauLogTypeFamilies)
             printf("Trying to reduce %s\n", toString(subject, {true}).c_str());
 
-        if (const TypeFamilyInstanceType* tfit = get<TypeFamilyInstanceType>(subject))
+        if (const TypeFunctionInstanceType* tfit = get<TypeFunctionInstanceType>(subject))
         {
             SkipTestResult testCyclic = testForSkippability(subject);
 
-            if (!testParameters(subject, tfit) && testCyclic != SkipTestResult::CyclicTypeFamily)
+            if (!testParameters(subject, tfit) && testCyclic != SkipTestResult::CyclicTypeFunction)
             {
                 if (FFlag::DebugLuauLogTypeFamilies)
                     printf("Irreducible due to irreducible/pending and a non-cyclic family\n");
@@ -347,8 +347,8 @@ struct FamilyReducer
             if (tryGuessing(subject))
                 return;
 
-            TypeFamilyReductionResult<TypeId> result = tfit->family->reducer(subject, tfit->typeArguments, tfit->packArguments, NotNull{&ctx});
+            TypeFunctionReductionResult<TypeId> result = tfit->family->reducer(subject, tfit->typeArguments, tfit->packArguments, NotNull{&ctx});
-            handleFamilyReduction(subject, result);
+            handleTypeFunctionReduction(subject, result);
         }
     }
 
@@ -363,7 +363,7 @@ struct FamilyReducer
         if (FFlag::DebugLuauLogTypeFamilies)
             printf("Trying to reduce %s\n", toString(subject, {true}).c_str());
 
-        if (const TypeFamilyInstanceTypePack* tfit = get<TypeFamilyInstanceTypePack>(subject))
+        if (const TypeFunctionInstanceTypePack* tfit = get<TypeFunctionInstanceTypePack>(subject))
         {
             if (!testParameters(subject, tfit))
                 return;
@@ -371,8 +371,8 @@ struct FamilyReducer
             if (tryGuessing(subject))
                 return;
 
-            TypeFamilyReductionResult<TypePackId> result = tfit->family->reducer(subject, tfit->typeArguments, tfit->packArguments, NotNull{&ctx});
+            TypeFunctionReductionResult<TypePackId> result = tfit->family->reducer(subject, tfit->typeArguments, tfit->packArguments, NotNull{&ctx});
-            handleFamilyReduction(subject, result);
+            handleTypeFunctionReduction(subject, result);
         }
     }
 
@@ -385,10 +385,10 @@ struct FamilyReducer
     }
 };
 
-static FamilyGraphReductionResult reduceFamiliesInternal(VecDeque<TypeId> queuedTys, VecDeque<TypePackId> queuedTps, TypeOrTypePackIdSet shouldGuess,
+static FunctionGraphReductionResult reduceFamiliesInternal(VecDeque<TypeId> queuedTys, VecDeque<TypePackId> queuedTps, TypeOrTypePackIdSet shouldGuess,
-    std::vector<TypeId> cyclics, Location location, TypeFamilyContext ctx, bool force)
+    std::vector<TypeId> cyclics, Location location, TypeFunctionContext ctx, bool force)
 {
-    FamilyReducer reducer{std::move(queuedTys), std::move(queuedTps), std::move(shouldGuess), std::move(cyclics), location, ctx, force};
+    TypeFunctionReducer reducer{std::move(queuedTys), std::move(queuedTps), std::move(shouldGuess), std::move(cyclics), location, ctx, force};
     int iterationCount = 0;
 
     while (!reducer.done())
@@ -406,7 +406,7 @@ static FamilyGraphReductionResult reduceFamiliesInternal(VecDeque<TypeId> queued
     return std::move(reducer.result);
 }
 
-FamilyGraphReductionResult reduceFamilies(TypeId entrypoint, Location location, TypeFamilyContext ctx, bool force)
+FunctionGraphReductionResult reduceTypeFunctions(TypeId entrypoint, Location location, TypeFunctionContext ctx, bool force)
 {
     InstanceCollector collector;
 
@@ -416,7 +416,7 @@ FamilyGraphReductionResult reduceFamilies(TypeId entrypoint, Location location,
     }
     catch (RecursionLimitException&)
     {
-        return FamilyGraphReductionResult{};
+        return FunctionGraphReductionResult{};
     }
 
     if (collector.tys.empty() && collector.tps.empty())
@@ -426,7 +426,7 @@ FamilyGraphReductionResult reduceFamilies(TypeId entrypoint, Location location,
         std::move(collector.cyclicInstance), location, ctx, force);
 }
 
-FamilyGraphReductionResult reduceFamilies(TypePackId entrypoint, Location location, TypeFamilyContext ctx, bool force)
+FunctionGraphReductionResult reduceTypeFunctions(TypePackId entrypoint, Location location, TypeFunctionContext ctx, bool force)
 {
     InstanceCollector collector;
 
@@ -436,7 +436,7 @@ FamilyGraphReductionResult reduceFamilies(TypePackId entrypoint, Location locati
     }
     catch (RecursionLimitException&)
     {
-        return FamilyGraphReductionResult{};
+        return FunctionGraphReductionResult{};
     }
 
     if (collector.tys.empty() && collector.tps.empty())
@@ -448,12 +448,12 @@ FamilyGraphReductionResult reduceFamilies(TypePackId entrypoint, Location locati
 
 bool isPending(TypeId ty, ConstraintSolver* solver)
 {
-    return is<BlockedType, PendingExpansionType, TypeFamilyInstanceType>(ty) || (solver && solver->hasUnresolvedConstraints(ty));
+    return is<BlockedType, PendingExpansionType, TypeFunctionInstanceType>(ty) || (solver && solver->hasUnresolvedConstraints(ty));
 }
 
 template<typename F, typename... Args>
-static std::optional<TypeFamilyReductionResult<TypeId>> tryDistributeTypeFamilyApp(F f, TypeId instance, const std::vector<TypeId>& typeParams,
+static std::optional<TypeFunctionReductionResult<TypeId>> tryDistributeTypeFunctionApp(F f, TypeId instance, const std::vector<TypeId>& typeParams,
-    const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx, Args&&... args)
+    const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx, Args&&... args)
 {
     // op (a | b) (c | d) ~ (op a (c | d)) | (op b (c | d)) ~ (op a c) | (op a d) | (op b c) | (op b d)
     bool uninhabited = false;
@@ -483,7 +483,7 @@ static std::optional<TypeFamilyReductionResult<TypeId>> tryDistributeTypeFamilyA
 
         cartesianProductSize *= std::distance(begin(ut), end(ut));
 
-        // TODO: We'd like to report that the type family application is too complex here.
+        // TODO: We'd like to report that the type function application is too complex here.
         if (size_t(DFInt::LuauTypeFamilyApplicationCartesianProductLimit) <= cartesianProductSize)
             return {{std::nullopt, true, {}, {}}};
     }
@@ -498,7 +498,7 @@ static std::optional<TypeFamilyReductionResult<TypeId>> tryDistributeTypeFamilyA
     {
         arguments[unionIndex] = option;
 
-        TypeFamilyReductionResult<TypeId> result = f(instance, arguments, packParams, ctx, args...);
+        TypeFunctionReductionResult<TypeId> result = f(instance, arguments, packParams, ctx, args...);
         blockedTypes.insert(blockedTypes.end(), result.blockedTypes.begin(), result.blockedTypes.end());
         uninhabited |= result.uninhabited;
 
@@ -516,8 +516,8 @@ static std::optional<TypeFamilyReductionResult<TypeId>> tryDistributeTypeFamilyA
         if (results.size() == 1)
             return {{results[0], false, {}, {}}};
 
-        TypeId resultTy = ctx->arena->addType(TypeFamilyInstanceType{
+        TypeId resultTy = ctx->arena->addType(TypeFunctionInstanceType{
-            NotNull{&builtinTypeFunctions().unionFamily},
+            NotNull{&builtinTypeFunctions().unionFunc},
             std::move(results),
             {},
         });
@@ -528,12 +528,12 @@ static std::optional<TypeFamilyReductionResult<TypeId>> tryDistributeTypeFamilyA
     return std::nullopt;
 }
 
-TypeFamilyReductionResult<TypeId> notFamilyFn(
+TypeFunctionReductionResult<TypeId> notFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("not type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("not type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -545,19 +545,19 @@ TypeFamilyReductionResult<TypeId> notFamilyFn(
     if (isPending(ty, ctx->solver))
         return {std::nullopt, false, {ty}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(notFamilyFn, instance, typeParams, packParams, ctx))
+    if (auto result = tryDistributeTypeFunctionApp(notFamilyFn, instance, typeParams, packParams, ctx))
         return *result;
 
     // `not` operates on anything and returns a `boolean` always.
     return {ctx->builtins->booleanType, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> lenFamilyFn(
+TypeFunctionReductionResult<TypeId> lenFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("len type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("len type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -604,7 +604,7 @@ TypeFamilyReductionResult<TypeId> lenFamilyFn(
     if (normTy->hasTopTable() || get<TableType>(normalizedOperand))
         return {ctx->builtins->numberType, false, {}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(notFamilyFn, instance, typeParams, packParams, ctx))
+    if (auto result = tryDistributeTypeFunctionApp(notFamilyFn, instance, typeParams, packParams, ctx))
         return *result;
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
@@ -644,12 +644,12 @@ TypeFamilyReductionResult<TypeId> lenFamilyFn(
     return {ctx->builtins->numberType, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> unmFamilyFn(
+TypeFunctionReductionResult<TypeId> unmFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("unm type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("unm type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -689,7 +689,7 @@ TypeFamilyReductionResult<TypeId> unmFamilyFn(
     if (normTy->isExactlyNumber())
         return {ctx->builtins->numberType, false, {}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(notFamilyFn, instance, typeParams, packParams, ctx))
+    if (auto result = tryDistributeTypeFunctionApp(notFamilyFn, instance, typeParams, packParams, ctx))
         return *result;
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
@@ -731,7 +731,7 @@ TypeFamilyReductionResult<TypeId> unmFamilyFn(
         return {std::nullopt, true, {}, {}};
 }
 
-NotNull<Constraint> TypeFamilyContext::pushConstraint(ConstraintV&& c)
+NotNull<Constraint> TypeFunctionContext::pushConstraint(ConstraintV&& c)
 {
     LUAU_ASSERT(solver);
     NotNull<Constraint> newConstraint = solver->pushConstraint(scope, constraint ? constraint->location : Location{}, std::move(c));
@@ -744,12 +744,12 @@ NotNull<Constraint> TypeFamilyContext::pushConstraint(ConstraintV&& c)
     return newConstraint;
 }
 
-TypeFamilyReductionResult<TypeId> numericBinopFamilyFn(TypeId instance, const std::vector<TypeId>& typeParams,
+TypeFunctionReductionResult<TypeId> numericBinopFamilyFn(TypeId instance, const std::vector<TypeId>& typeParams,
-    const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx, const std::string metamethod)
+    const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx, const std::string metamethod)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("encountered a type family instance without the required argument structure");
+        ctx->ice->ice("encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -803,7 +803,7 @@ TypeFamilyReductionResult<TypeId> numericBinopFamilyFn(TypeId instance, const st
     if (normLhsTy->isExactlyNumber() && normRhsTy->isExactlyNumber())
         return {ctx->builtins->numberType, false, {}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(numericBinopFamilyFn, instance, typeParams, packParams, ctx, metamethod))
+    if (auto result = tryDistributeTypeFunctionApp(numericBinopFamilyFn, instance, typeParams, packParams, ctx, metamethod))
         return *result;
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
@@ -847,96 +847,96 @@ TypeFamilyReductionResult<TypeId> numericBinopFamilyFn(TypeId instance, const st
     return {extracted.head.front(), false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> addFamilyFn(
+TypeFunctionReductionResult<TypeId> addFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("add type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("add type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__add");
 }
 
-TypeFamilyReductionResult<TypeId> subFamilyFn(
+TypeFunctionReductionResult<TypeId> subFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("sub type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("sub type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__sub");
 }
 
-TypeFamilyReductionResult<TypeId> mulFamilyFn(
+TypeFunctionReductionResult<TypeId> mulFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("mul type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("mul type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__mul");
 }
 
-TypeFamilyReductionResult<TypeId> divFamilyFn(
+TypeFunctionReductionResult<TypeId> divFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("div type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("div type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__div");
 }
 
-TypeFamilyReductionResult<TypeId> idivFamilyFn(
+TypeFunctionReductionResult<TypeId> idivFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("integer div type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("integer div type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__idiv");
 }
 
-TypeFamilyReductionResult<TypeId> powFamilyFn(
+TypeFunctionReductionResult<TypeId> powFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("pow type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("pow type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__pow");
 }
 
-TypeFamilyReductionResult<TypeId> modFamilyFn(
+TypeFunctionReductionResult<TypeId> modFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("modulo type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("modulo type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return numericBinopFamilyFn(instance, typeParams, packParams, ctx, "__mod");
 }
 
-TypeFamilyReductionResult<TypeId> concatFamilyFn(
+TypeFunctionReductionResult<TypeId> concatFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("concat type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("concat type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -987,7 +987,7 @@ TypeFamilyReductionResult<TypeId> concatFamilyFn(
     if ((normLhsTy->isSubtypeOfString() || normLhsTy->isExactlyNumber()) && (normRhsTy->isSubtypeOfString() || normRhsTy->isExactlyNumber()))
         return {ctx->builtins->stringType, false, {}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(concatFamilyFn, instance, typeParams, packParams, ctx))
+    if (auto result = tryDistributeTypeFunctionApp(concatFamilyFn, instance, typeParams, packParams, ctx))
         return *result;
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
@@ -1039,12 +1039,12 @@ TypeFamilyReductionResult<TypeId> concatFamilyFn(
     return {ctx->builtins->stringType, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> andFamilyFn(
+TypeFunctionReductionResult<TypeId> andFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("and type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("and type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1090,12 +1090,12 @@ TypeFamilyReductionResult<TypeId> andFamilyFn(
     return {overallResult.result, false, std::move(blockedTypes), {}};
 }
 
-TypeFamilyReductionResult<TypeId> orFamilyFn(
+TypeFunctionReductionResult<TypeId> orFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("or type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("or type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1141,13 +1141,13 @@ TypeFamilyReductionResult<TypeId> orFamilyFn(
     return {overallResult.result, false, std::move(blockedTypes), {}};
 }
 
-static TypeFamilyReductionResult<TypeId> comparisonFamilyFn(TypeId instance, const std::vector<TypeId>& typeParams,
+static TypeFunctionReductionResult<TypeId> comparisonFamilyFn(TypeId instance, const std::vector<TypeId>& typeParams,
-    const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx, const std::string metamethod)
+    const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx, const std::string metamethod)
 {
 
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("encountered a type family instance without the required argument structure");
+        ctx->ice->ice("encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1238,7 +1238,7 @@ static TypeFamilyReductionResult<TypeId> comparisonFamilyFn(TypeId instance, con
     if (normLhsTy->isExactlyNumber() && normRhsTy->isExactlyNumber())
         return {ctx->builtins->booleanType, false, {}, {}};
 
-    if (auto result = tryDistributeTypeFamilyApp(comparisonFamilyFn, instance, typeParams, packParams, ctx, metamethod))
+    if (auto result = tryDistributeTypeFunctionApp(comparisonFamilyFn, instance, typeParams, packParams, ctx, metamethod))
         return *result;
 
     // findMetatableEntry demands the ability to emit errors, so we must give it
@@ -1280,36 +1280,36 @@ static TypeFamilyReductionResult<TypeId> comparisonFamilyFn(TypeId instance, con
     return {ctx->builtins->booleanType, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> ltFamilyFn(
+TypeFunctionReductionResult<TypeId> ltFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("lt type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("lt type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return comparisonFamilyFn(instance, typeParams, packParams, ctx, "__lt");
 }
 
-TypeFamilyReductionResult<TypeId> leFamilyFn(
+TypeFunctionReductionResult<TypeId> leFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("le type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("le type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return comparisonFamilyFn(instance, typeParams, packParams, ctx, "__le");
 }
 
-TypeFamilyReductionResult<TypeId> eqFamilyFn(
+TypeFunctionReductionResult<TypeId> eqFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("eq type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("eq type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1435,12 +1435,12 @@ struct FindRefinementBlockers : TypeOnceVisitor
 };
 
 
-TypeFamilyReductionResult<TypeId> refineFamilyFn(
+TypeFunctionReductionResult<TypeId> refineFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("refine type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("refine type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1520,12 +1520,12 @@ TypeFamilyReductionResult<TypeId> refineFamilyFn(
     return {resultTy, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> singletonFamilyFn(
+TypeFunctionReductionResult<TypeId> singletonFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("singleton type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("singleton type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1557,12 +1557,12 @@ TypeFamilyReductionResult<TypeId> singletonFamilyFn(
     return {ctx->builtins->unknownType, false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> unionFamilyFn(
+TypeFunctionReductionResult<TypeId> unionFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (!packParams.empty())
     {
-        ctx->ice->ice("union type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("union type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1618,12 +1618,12 @@ TypeFamilyReductionResult<TypeId> unionFamilyFn(
 }
 
 
-TypeFamilyReductionResult<TypeId> intersectFamilyFn(
+TypeFunctionReductionResult<TypeId> intersectFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (!packParams.empty())
     {
-        ctx->ice->ice("intersect type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("intersect type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1673,7 +1673,7 @@ TypeFamilyReductionResult<TypeId> intersectFamilyFn(
 // computes the keys of `ty` into `result`
 // `isRaw` parameter indicates whether or not we should follow __index metamethods
 // returns `false` if `result` should be ignored because the answer is "all strings"
-bool computeKeysOf(TypeId ty, Set<std::string>& result, DenseHashSet<TypeId>& seen, bool isRaw, NotNull<TypeFamilyContext> ctx)
+bool computeKeysOf(TypeId ty, Set<std::string>& result, DenseHashSet<TypeId>& seen, bool isRaw, NotNull<TypeFunctionContext> ctx)
 {
     // if the type is the top table type, the answer is just "all strings"
     if (get<PrimitiveType>(ty))
@@ -1725,12 +1725,12 @@ bool computeKeysOf(TypeId ty, Set<std::string>& result, DenseHashSet<TypeId>& se
     return false;
 }
 
-TypeFamilyReductionResult<TypeId> keyofFamilyImpl(
+TypeFunctionReductionResult<TypeId> keyofFamilyImpl(
-    const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx, bool isRaw)
+    const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx, bool isRaw)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("keyof type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("keyof type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1842,24 +1842,24 @@ TypeFamilyReductionResult<TypeId> keyofFamilyImpl(
     return {ctx->arena->addType(UnionType{singletons}), false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> keyofFamilyFn(
+TypeFunctionReductionResult<TypeId> keyofFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("keyof type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("keyof type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return keyofFamilyImpl(typeParams, packParams, ctx, /* isRaw */ false);
 }
 
-TypeFamilyReductionResult<TypeId> rawkeyofFamilyFn(
+TypeFunctionReductionResult<TypeId> rawkeyofFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 1 || !packParams.empty())
     {
-        ctx->ice->ice("rawkeyof type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("rawkeyof type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
@@ -1870,7 +1870,7 @@ TypeFamilyReductionResult<TypeId> rawkeyofFamilyFn(
    If found, appends that property to `result` and returns true
    Else, returns false */
 bool searchPropsAndIndexer(
-    TypeId ty, TableType::Props tblProps, std::optional<TableIndexer> tblIndexer, DenseHashSet<TypeId>& result, NotNull<TypeFamilyContext> ctx)
+    TypeId ty, TableType::Props tblProps, std::optional<TableIndexer> tblIndexer, DenseHashSet<TypeId>& result, NotNull<TypeFunctionContext> ctx)
 {
     ty = follow(ty);
 
@@ -1920,7 +1920,7 @@ bool searchPropsAndIndexer(
 /* Handles recursion / metamethods of tables/classes
    `isRaw` parameter indicates whether or not we should follow __index metamethods
    returns false if property of `ty` could not be found */
-bool tblIndexInto(TypeId indexer, TypeId indexee, DenseHashSet<TypeId>& result, NotNull<TypeFamilyContext> ctx, bool isRaw)
+bool tblIndexInto(TypeId indexer, TypeId indexee, DenseHashSet<TypeId>& result, NotNull<TypeFunctionContext> ctx, bool isRaw)
 {
     indexer = follow(indexer);
     indexee = follow(indexee);
@@ -1960,8 +1960,8 @@ bool tblIndexInto(TypeId indexer, TypeId indexee, DenseHashSet<TypeId>& result,
 /* Vocabulary note: indexee refers to the type that contains the properties,
                     indexer refers to the type that is used to access indexee
    Example:         index<Person, "name"> => `Person` is the indexee and `"name"` is the indexer */
-TypeFamilyReductionResult<TypeId> indexFamilyImpl(
+TypeFunctionReductionResult<TypeId> indexFamilyImpl(
-    const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx, bool isRaw)
+    const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx, bool isRaw)
 {
     TypeId indexeeTy = follow(typeParams.at(0));
     std::shared_ptr<const NormalizedType> indexeeNormTy = ctx->normalizer->normalize(indexeeTy);
@@ -2064,104 +2064,104 @@ TypeFamilyReductionResult<TypeId> indexFamilyImpl(
     return {ctx->arena->addType(UnionType{std::vector<TypeId>(properties.begin(), properties.end())}), false, {}, {}};
 }
 
-TypeFamilyReductionResult<TypeId> indexFamilyFn(
+TypeFunctionReductionResult<TypeId> indexFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("index type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("index type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return indexFamilyImpl(typeParams, packParams, ctx, /* isRaw */ false);
 }
 
-TypeFamilyReductionResult<TypeId> rawgetFamilyFn(
+TypeFunctionReductionResult<TypeId> rawgetFamilyFn(
-    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFamilyContext> ctx)
+    TypeId instance, const std::vector<TypeId>& typeParams, const std::vector<TypePackId>& packParams, NotNull<TypeFunctionContext> ctx)
 {
     if (typeParams.size() != 2 || !packParams.empty())
     {
-        ctx->ice->ice("rawget type family: encountered a type family instance without the required argument structure");
+        ctx->ice->ice("rawget type function: encountered a type function instance without the required argument structure");
         LUAU_ASSERT(false);
     }
 
     return indexFamilyImpl(typeParams, packParams, ctx, /* isRaw */ true);
 }
 
-BuiltinTypeFamilies::BuiltinTypeFamilies()
+BuiltinTypeFunctions::BuiltinTypeFunctions()
-    : notFamily{"not", notFamilyFn}
+    : notFunc{"not", notFamilyFn}
-    , lenFamily{"len", lenFamilyFn}
+    , lenFunc{"len", lenFamilyFn}
-    , unmFamily{"unm", unmFamilyFn}
+    , unmFunc{"unm", unmFamilyFn}
-    , addFamily{"add", addFamilyFn}
+    , addFunc{"add", addFamilyFn}
-    , subFamily{"sub", subFamilyFn}
+    , subFunc{"sub", subFamilyFn}
-    , mulFamily{"mul", mulFamilyFn}
+    , mulFunc{"mul", mulFamilyFn}
-    , divFamily{"div", divFamilyFn}
+    , divFunc{"div", divFamilyFn}
-    , idivFamily{"idiv", idivFamilyFn}
+    , idivFunc{"idiv", idivFamilyFn}
-    , powFamily{"pow", powFamilyFn}
+    , powFunc{"pow", powFamilyFn}
-    , modFamily{"mod", modFamilyFn}
+    , modFunc{"mod", modFamilyFn}
-    , concatFamily{"concat", concatFamilyFn}
+    , concatFunc{"concat", concatFamilyFn}
-    , andFamily{"and", andFamilyFn}
+    , andFunc{"and", andFamilyFn}
-    , orFamily{"or", orFamilyFn}
+    , orFunc{"or", orFamilyFn}
-    , ltFamily{"lt", ltFamilyFn}
+    , ltFunc{"lt", ltFamilyFn}
-    , leFamily{"le", leFamilyFn}
+    , leFunc{"le", leFamilyFn}
-    , eqFamily{"eq", eqFamilyFn}
+    , eqFunc{"eq", eqFamilyFn}
-    , refineFamily{"refine", refineFamilyFn}
+    , refineFunc{"refine", refineFamilyFn}
-    , singletonFamily{"singleton", singletonFamilyFn}
+    , singletonFunc{"singleton", singletonFamilyFn}
-    , unionFamily{"union", unionFamilyFn}
+    , unionFunc{"union", unionFamilyFn}
-    , intersectFamily{"intersect", intersectFamilyFn}
+    , intersectFunc{"intersect", intersectFamilyFn}
-    , keyofFamily{"keyof", keyofFamilyFn}
+    , keyofFunc{"keyof", keyofFamilyFn}
-    , rawkeyofFamily{"rawkeyof", rawkeyofFamilyFn}
+    , rawkeyofFunc{"rawkeyof", rawkeyofFamilyFn}
-    , indexFamily{"index", indexFamilyFn}
+    , indexFunc{"index", indexFamilyFn}
-    , rawgetFamily{"rawget", rawgetFamilyFn}
+    , rawgetFunc{"rawget", rawgetFamilyFn}
 {
 }
 
-void BuiltinTypeFamilies::addToScope(NotNull<TypeArena> arena, NotNull<Scope> scope) const
+void BuiltinTypeFunctions::addToScope(NotNull<TypeArena> arena, NotNull<Scope> scope) const
 {
-    // make a type function for a one-argument type family
+    // make a type function for a one-argument type function
-    auto mkUnaryTypeFamily = [&](const TypeFamily* family) {
+    auto mkUnaryTypeFunction = [&](const TypeFunction* tf) {
         TypeId t = arena->addType(GenericType{"T"});
         GenericTypeDefinition genericT{t};
 
-        return TypeFun{{genericT}, arena->addType(TypeFamilyInstanceType{NotNull{family}, {t}, {}})};
+        return TypeFun{{genericT}, arena->addType(TypeFunctionInstanceType{NotNull{tf}, {t}, {}})};
     };
 
-    // make a type function for a two-argument type family
+    // make a type function for a two-argument type function
-    auto mkBinaryTypeFamily = [&](const TypeFamily* family) {
+    auto mkBinaryTypeFunction = [&](const TypeFunction* tf) {
         TypeId t = arena->addType(GenericType{"T"});
         TypeId u = arena->addType(GenericType{"U"});
         GenericTypeDefinition genericT{t};
         GenericTypeDefinition genericU{u, {t}};
 
-        return TypeFun{{genericT, genericU}, arena->addType(TypeFamilyInstanceType{NotNull{family}, {t, u}, {}})};
+        return TypeFun{{genericT, genericU}, arena->addType(TypeFunctionInstanceType{NotNull{tf}, {t, u}, {}})};
     };
 
-    scope->exportedTypeBindings[lenFamily.name] = mkUnaryTypeFamily(&lenFamily);
+    scope->exportedTypeBindings[lenFunc.name] = mkUnaryTypeFunction(&lenFunc);
-    scope->exportedTypeBindings[unmFamily.name] = mkUnaryTypeFamily(&unmFamily);
+    scope->exportedTypeBindings[unmFunc.name] = mkUnaryTypeFunction(&unmFunc);
 
-    scope->exportedTypeBindings[addFamily.name] = mkBinaryTypeFamily(&addFamily);
+    scope->exportedTypeBindings[addFunc.name] = mkBinaryTypeFunction(&addFunc);
-    scope->exportedTypeBindings[subFamily.name] = mkBinaryTypeFamily(&subFamily);
+    scope->exportedTypeBindings[subFunc.name] = mkBinaryTypeFunction(&subFunc);
-    scope->exportedTypeBindings[mulFamily.name] = mkBinaryTypeFamily(&mulFamily);
+    scope->exportedTypeBindings[mulFunc.name] = mkBinaryTypeFunction(&mulFunc);
-    scope->exportedTypeBindings[divFamily.name] = mkBinaryTypeFamily(&divFamily);
+    scope->exportedTypeBindings[divFunc.name] = mkBinaryTypeFunction(&divFunc);
-    scope->exportedTypeBindings[idivFamily.name] = mkBinaryTypeFamily(&idivFamily);
+    scope->exportedTypeBindings[idivFunc.name] = mkBinaryTypeFunction(&idivFunc);
-    scope->exportedTypeBindings[powFamily.name] = mkBinaryTypeFamily(&powFamily);
+    scope->exportedTypeBindings[powFunc.name] = mkBinaryTypeFunction(&powFunc);
-    scope->exportedTypeBindings[modFamily.name] = mkBinaryTypeFamily(&modFamily);
+    scope->exportedTypeBindings[modFunc.name] = mkBinaryTypeFunction(&modFunc);
-    scope->exportedTypeBindings[concatFamily.name] = mkBinaryTypeFamily(&concatFamily);
+    scope->exportedTypeBindings[concatFunc.name] = mkBinaryTypeFunction(&concatFunc);
 
-    scope->exportedTypeBindings[ltFamily.name] = mkBinaryTypeFamily(&ltFamily);
+    scope->exportedTypeBindings[ltFunc.name] = mkBinaryTypeFunction(&ltFunc);
-    scope->exportedTypeBindings[leFamily.name] = mkBinaryTypeFamily(&leFamily);
+    scope->exportedTypeBindings[leFunc.name] = mkBinaryTypeFunction(&leFunc);
-    scope->exportedTypeBindings[eqFamily.name] = mkBinaryTypeFamily(&eqFamily);
+    scope->exportedTypeBindings[eqFunc.name] = mkBinaryTypeFunction(&eqFunc);
 
-    scope->exportedTypeBindings[keyofFamily.name] = mkUnaryTypeFamily(&keyofFamily);
+    scope->exportedTypeBindings[keyofFunc.name] = mkUnaryTypeFunction(&keyofFunc);
-    scope->exportedTypeBindings[rawkeyofFamily.name] = mkUnaryTypeFamily(&rawkeyofFamily);
+    scope->exportedTypeBindings[rawkeyofFunc.name] = mkUnaryTypeFunction(&rawkeyofFunc);
 
-    scope->exportedTypeBindings[indexFamily.name] = mkBinaryTypeFamily(&indexFamily);
+    scope->exportedTypeBindings[indexFunc.name] = mkBinaryTypeFunction(&indexFunc);
-    scope->exportedTypeBindings[rawgetFamily.name] = mkBinaryTypeFamily(&rawgetFamily);
+    scope->exportedTypeBindings[rawgetFunc.name] = mkBinaryTypeFunction(&rawgetFunc);
 }
 
-const BuiltinTypeFamilies& builtinTypeFunctions()
+const BuiltinTypeFunctions& builtinTypeFunctions()
 {
-    static std::unique_ptr<const BuiltinTypeFamilies> result = std::make_unique<BuiltinTypeFamilies>();
+    static std::unique_ptr<const BuiltinTypeFunctions> result = std::make_unique<BuiltinTypeFunctions>();
 
     return *result;
 }

Analysis/src/TypeFunctionReductionGuesser.cpp

@@ -1,9 +1,9 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/TypeFamilyReductionGuesser.h"
+#include "Luau/TypeFunctionReductionGuesser.h"
 
 #include "Luau/DenseHash.h"
 #include "Luau/Normalize.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/Type.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypeUtils.h"
@@ -23,7 +23,7 @@ struct InstanceCollector2 : TypeOnceVisitor
     DenseHashSet<TypeId> cyclicInstance{nullptr};
     DenseHashSet<TypeId> instanceArguments{nullptr};
 
-    bool visit(TypeId ty, const TypeFamilyInstanceType& it) override
+    bool visit(TypeId ty, const TypeFunctionInstanceType& it) override
     {
         // TypeOnceVisitor performs a depth-first traversal in the absence of
         // cycles. This means that by pushing to the front of the queue, we will
@@ -41,7 +41,7 @@ struct InstanceCollector2 : TypeOnceVisitor
     {
         /// Detected cyclic type pack
         TypeId t = follow(ty);
-        if (get<TypeFamilyInstanceType>(t))
+        if (get<TypeFunctionInstanceType>(t))
             cyclicInstance.insert(t);
     }
 
@@ -50,7 +50,7 @@ struct InstanceCollector2 : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypePackId tp, const TypeFamilyInstanceTypePack&) override
+    bool visit(TypePackId tp, const TypeFunctionInstanceTypePack&) override
     {
         // TypeOnceVisitor performs a depth-first traversal in the absence of
         // cycles. This means that by pushing to the front of the queue, we will
@@ -65,14 +65,14 @@ struct InstanceCollector2 : TypeOnceVisitor
 
 
 
-TypeFamilyReductionGuesser::TypeFamilyReductionGuesser(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Normalizer> normalizer)
+TypeFunctionReductionGuesser::TypeFunctionReductionGuesser(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtins, NotNull<Normalizer> normalizer)
     : arena(arena)
     , builtins(builtins)
     , normalizer(normalizer)
 {
 }
 
-bool TypeFamilyReductionGuesser::isFunctionGenericsSaturated(const FunctionType& ftv, DenseHashSet<TypeId>& argsUsed)
+bool TypeFunctionReductionGuesser::isFunctionGenericsSaturated(const FunctionType& ftv, DenseHashSet<TypeId>& argsUsed)
 {
     bool sameSize = ftv.generics.size() == argsUsed.size();
     bool allGenericsAppear = true;
@@ -81,7 +81,7 @@ bool TypeFamilyReductionGuesser::isFunctionGenericsSaturated(const FunctionType&
     return sameSize && allGenericsAppear;
 }
 
-void TypeFamilyReductionGuesser::dumpGuesses()
+void TypeFunctionReductionGuesser::dumpGuesses()
 {
     for (auto [tf, t] : familyReducesTo)
         printf("Type family %s ~~> %s\n", toString(tf).c_str(), toString(t).c_str());
@@ -89,7 +89,7 @@ void TypeFamilyReductionGuesser::dumpGuesses()
         printf("Substitute %s for %s\n", toString(t).c_str(), toString(t_).c_str());
 }
 
-std::optional<TypeId> TypeFamilyReductionGuesser::guess(TypeId typ)
+std::optional<TypeId> TypeFunctionReductionGuesser::guess(TypeId typ)
 {
     std::optional<TypeId> guessedType = guessType(typ);
 
@@ -97,13 +97,13 @@ std::optional<TypeId> TypeFamilyReductionGuesser::guess(TypeId typ)
         return {};
 
     TypeId guess = follow(*guessedType);
-    if (get<TypeFamilyInstanceType>(guess))
+    if (get<TypeFunctionInstanceType>(guess))
         return {};
 
     return guess;
 }
 
-std::optional<TypePackId> TypeFamilyReductionGuesser::guess(TypePackId tp)
+std::optional<TypePackId> TypeFunctionReductionGuesser::guess(TypePackId tp)
 {
     auto [head, tail] = flatten(tp);
 
@@ -118,7 +118,7 @@ std::optional<TypePackId> TypeFamilyReductionGuesser::guess(TypePackId tp)
             return {};
 
         TypeId guess = follow(*guessedType);
-        if (get<TypeFamilyInstanceType>(guess))
+        if (get<TypeFunctionInstanceType>(guess))
             return {};
 
         guessedHead.push_back(*guessedType);
@@ -127,7 +127,7 @@ std::optional<TypePackId> TypeFamilyReductionGuesser::guess(TypePackId tp)
     return arena->addTypePack(TypePack{guessedHead, tail});
 }
 
-TypeFamilyReductionGuessResult TypeFamilyReductionGuesser::guessTypeFamilyReductionForFunction(
+TypeFunctionReductionGuessResult TypeFunctionReductionGuesser::guessTypeFunctionReductionForFunctionExpr(
     const AstExprFunction& expr, const FunctionType* ftv, TypeId retTy)
 {
     InstanceCollector2 collector;
@@ -136,7 +136,7 @@ TypeFamilyReductionGuessResult TypeFamilyReductionGuesser::guessTypeFamilyReduct
     cyclicInstances = std::move(collector.cyclicInstance);
 
     if (isFunctionGenericsSaturated(*ftv, collector.instanceArguments))
-        return TypeFamilyReductionGuessResult{{}, nullptr, false};
+        return TypeFunctionReductionGuessResult{{}, nullptr, false};
     infer();
 
     std::vector<std::pair<std::string, TypeId>> results;
@@ -157,7 +157,7 @@ TypeFamilyReductionGuessResult TypeFamilyReductionGuesser::guessTypeFamilyReduct
         if (!guessedType.has_value())
             continue;
         TypeId guess = follow(*guessedType);
-        if (get<TypeFamilyInstanceType>(guess))
+        if (get<TypeFunctionInstanceType>(guess))
             continue;
 
         results.push_back({local->name.value, guess});
@@ -170,7 +170,7 @@ TypeFamilyReductionGuessResult TypeFamilyReductionGuesser::guessTypeFamilyReduct
         recommendedAnnotation = builtins->unknownType;
     else
         recommendedAnnotation = follow(*guessedReturnType);
-    if (auto t = get<TypeFamilyInstanceType>(recommendedAnnotation))
+    if (auto t = get<TypeFunctionInstanceType>(recommendedAnnotation))
         recommendedAnnotation = builtins->unknownType;
 
     toInfer.clear();
@@ -178,10 +178,10 @@ TypeFamilyReductionGuessResult TypeFamilyReductionGuesser::guessTypeFamilyReduct
     familyReducesTo.clear();
     substitutable.clear();
 
-    return TypeFamilyReductionGuessResult{results, recommendedAnnotation};
+    return TypeFunctionReductionGuessResult{results, recommendedAnnotation};
 }
 
-std::optional<TypeId> TypeFamilyReductionGuesser::guessType(TypeId arg)
+std::optional<TypeId> TypeFunctionReductionGuesser::guessType(TypeId arg)
 {
     TypeId t = follow(arg);
     if (substitutable.contains(t))
@@ -189,12 +189,12 @@ std::optional<TypeId> TypeFamilyReductionGuesser::guessType(TypeId arg)
         TypeId subst = follow(substitutable[t]);
         if (subst == t || substitutable.contains(subst))
             return subst;
-        else if (!get<TypeFamilyInstanceType>(subst))
+        else if (!get<TypeFunctionInstanceType>(subst))
             return subst;
         else
             return guessType(subst);
     }
-    if (get<TypeFamilyInstanceType>(t))
+    if (get<TypeFunctionInstanceType>(t))
     {
         if (familyReducesTo.contains(t))
             return familyReducesTo[t];
@@ -202,41 +202,41 @@ std::optional<TypeId> TypeFamilyReductionGuesser::guessType(TypeId arg)
     return {};
 }
 
-bool TypeFamilyReductionGuesser::isNumericBinopFamily(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isNumericBinopFamily(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "add" || instance.family->name == "sub" || instance.family->name == "mul" || instance.family->name == "div" ||
            instance.family->name == "idiv" || instance.family->name == "pow" || instance.family->name == "mod";
 }
 
-bool TypeFamilyReductionGuesser::isComparisonFamily(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isComparisonFamily(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "lt" || instance.family->name == "le" || instance.family->name == "eq";
 }
 
-bool TypeFamilyReductionGuesser::isOrAndFamily(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isOrAndFamily(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "or" || instance.family->name == "and";
 }
 
-bool TypeFamilyReductionGuesser::isNotFamily(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isNotFamily(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "not";
 }
 
-bool TypeFamilyReductionGuesser::isLenFamily(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isLenFamily(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "len";
 }
 
-bool TypeFamilyReductionGuesser::isUnaryMinus(const TypeFamilyInstanceType& instance)
+bool TypeFunctionReductionGuesser::isUnaryMinus(const TypeFunctionInstanceType& instance)
 {
     return instance.family->name == "unm";
 }
 
 // Operand is assignable if it looks like a cyclic family instance, or a generic type
-bool TypeFamilyReductionGuesser::operandIsAssignable(TypeId ty)
+bool TypeFunctionReductionGuesser::operandIsAssignable(TypeId ty)
 {
-    if (get<TypeFamilyInstanceType>(ty))
+    if (get<TypeFunctionInstanceType>(ty))
         return true;
     if (get<GenericType>(ty))
         return true;
@@ -245,17 +245,17 @@ bool TypeFamilyReductionGuesser::operandIsAssignable(TypeId ty)
     return false;
 }
 
-std::shared_ptr<const NormalizedType> TypeFamilyReductionGuesser::normalize(TypeId ty)
+std::shared_ptr<const NormalizedType> TypeFunctionReductionGuesser::normalize(TypeId ty)
 {
     return normalizer->normalize(ty);
 }
 
 
-std::optional<TypeId> TypeFamilyReductionGuesser::tryAssignOperandType(TypeId ty)
+std::optional<TypeId> TypeFunctionReductionGuesser::tryAssignOperandType(TypeId ty)
 {
-    // Because we collect innermost instances first, if we see a typefamily instance as an operand,
+    // Because we collect innermost instances first, if we see a type function instance as an operand,
     // We try to check if we guessed a type for it
-    if (auto tfit = get<TypeFamilyInstanceType>(ty))
+    if (auto tfit = get<TypeFunctionInstanceType>(ty))
     {
         if (familyReducesTo.contains(ty))
             return {familyReducesTo[ty]};
@@ -272,30 +272,30 @@ std::optional<TypeId> TypeFamilyReductionGuesser::tryAssignOperandType(TypeId ty
     return {};
 }
 
-void TypeFamilyReductionGuesser::step()
+void TypeFunctionReductionGuesser::step()
 {
     TypeId t = toInfer.front();
     toInfer.pop_front();
     t = follow(t);
-    if (auto tf = get<TypeFamilyInstanceType>(t))
+    if (auto tf = get<TypeFunctionInstanceType>(t))
-        inferTypeFamilySubstitutions(t, tf);
+        inferTypeFunctionSubstitutions(t, tf);
 }
 
-void TypeFamilyReductionGuesser::infer()
+void TypeFunctionReductionGuesser::infer()
 {
     while (!done())
         step();
 }
 
-bool TypeFamilyReductionGuesser::done()
+bool TypeFunctionReductionGuesser::done()
 {
     return toInfer.empty();
 }
 
-void TypeFamilyReductionGuesser::inferTypeFamilySubstitutions(TypeId ty, const TypeFamilyInstanceType* instance)
+void TypeFunctionReductionGuesser::inferTypeFunctionSubstitutions(TypeId ty, const TypeFunctionInstanceType* instance)
 {
 
-    TypeFamilyInferenceResult result;
+    TypeFunctionInferenceResult result;
     LUAU_ASSERT(instance);
     // TODO: Make an inexhaustive version of this warn in the compiler?
     if (isNumericBinopFamily(*instance))
@@ -323,7 +323,7 @@ void TypeFamilyReductionGuesser::inferTypeFamilySubstitutions(TypeId ty, const T
         {
             TypeId arg = follow(instance->typeArguments[i]);
             TypeId inference = follow(result.operandInference[i]);
-            if (auto tfit = get<TypeFamilyInstanceType>(arg))
+            if (auto tfit = get<TypeFunctionInstanceType>(arg))
             {
                 if (!familyReducesTo.contains(arg))
                     familyReducesTo.try_insert(arg, inference);
@@ -334,14 +334,14 @@ void TypeFamilyReductionGuesser::inferTypeFamilySubstitutions(TypeId ty, const T
     }
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferNumericBinopFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferNumericBinopFamily(const TypeFunctionInstanceType* instance)
 {
     LUAU_ASSERT(instance->typeArguments.size() == 2);
-    TypeFamilyInferenceResult defaultNumericBinopInference{{builtins->numberType, builtins->numberType}, builtins->numberType};
+    TypeFunctionInferenceResult defaultNumericBinopInference{{builtins->numberType, builtins->numberType}, builtins->numberType};
     return defaultNumericBinopInference;
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferComparisonFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferComparisonFamily(const TypeFunctionInstanceType* instance)
 {
     LUAU_ASSERT(instance->typeArguments.size() == 2);
     // Comparison families are lt/le/eq.
@@ -350,8 +350,8 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferComparisonFamily(cons
     TypeId lhsTy = follow(instance->typeArguments[0]);
     TypeId rhsTy = follow(instance->typeArguments[1]);
 
-    auto comparisonInference = [&](TypeId op) -> TypeFamilyInferenceResult {
+    auto comparisonInference = [&](TypeId op) -> TypeFunctionInferenceResult {
-        return TypeFamilyInferenceResult{{op, op}, builtins->booleanType};
+        return TypeFunctionInferenceResult{{op, op}, builtins->booleanType};
     };
 
     if (std::optional<TypeId> ty = tryAssignOperandType(lhsTy))
@@ -365,7 +365,7 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferComparisonFamily(cons
     return comparisonInference(builtins->numberType);
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferOrAndFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferOrAndFamily(const TypeFunctionInstanceType* instance)
 {
 
     LUAU_ASSERT(instance->typeArguments.size() == 2);
@@ -377,7 +377,7 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferOrAndFamily(const Typ
         lhsTy = follow(*ty);
     if (std::optional<TypeId> ty = tryAssignOperandType(rhsTy))
         rhsTy = follow(*ty);
-    TypeFamilyInferenceResult defaultAndOrInference{{builtins->unknownType, builtins->unknownType}, builtins->booleanType};
+    TypeFunctionInferenceResult defaultAndOrInference{{builtins->unknownType, builtins->unknownType}, builtins->booleanType};
 
     std::shared_ptr<const NormalizedType> lty = normalize(lhsTy);
     std::shared_ptr<const NormalizedType> rty = normalize(lhsTy);
@@ -389,9 +389,9 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferOrAndFamily(const Typ
         if (operandIsAssignable(lhsTy) && operandIsAssignable(rhsTy))
             return defaultAndOrInference;
         if (operandIsAssignable(lhsTy))
-            return TypeFamilyInferenceResult{{builtins->unknownType, rhsTy}, rhsTy};
+            return TypeFunctionInferenceResult{{builtins->unknownType, rhsTy}, rhsTy};
         if (operandIsAssignable(rhsTy))
-            return TypeFamilyInferenceResult{{lhsTy, builtins->unknownType}, lhsTy};
+            return TypeFunctionInferenceResult{{lhsTy, builtins->unknownType}, lhsTy};
         if (lhsTruthy)
             return {{lhsTy, rhsTy}, lhsTy};
         if (rhsTruthy)
@@ -404,9 +404,9 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferOrAndFamily(const Typ
         if (operandIsAssignable(lhsTy) && operandIsAssignable(rhsTy))
             return defaultAndOrInference;
         if (operandIsAssignable(lhsTy))
-            return TypeFamilyInferenceResult{{}, rhsTy};
+            return TypeFunctionInferenceResult{{}, rhsTy};
         if (operandIsAssignable(rhsTy))
-            return TypeFamilyInferenceResult{{}, lhsTy};
+            return TypeFunctionInferenceResult{{}, lhsTy};
         if (lhsTruthy)
             return {{lhsTy, rhsTy}, rhsTy};
         else
@@ -416,7 +416,7 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferOrAndFamily(const Typ
     return defaultAndOrInference;
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferNotFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferNotFamily(const TypeFunctionInstanceType* instance)
 {
     LUAU_ASSERT(instance->typeArguments.size() == 1);
     TypeId opTy = follow(instance->typeArguments[0]);
@@ -425,7 +425,7 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferNotFamily(const TypeF
     return {{opTy}, builtins->booleanType};
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferLenFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferLenFamily(const TypeFunctionInstanceType* instance)
 {
     LUAU_ASSERT(instance->typeArguments.size() == 1);
     TypeId opTy = follow(instance->typeArguments[0]);
@@ -434,7 +434,7 @@ TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferLenFamily(const TypeF
     return {{opTy}, builtins->numberType};
 }
 
-TypeFamilyInferenceResult TypeFamilyReductionGuesser::inferUnaryMinusFamily(const TypeFamilyInstanceType* instance)
+TypeFunctionInferenceResult TypeFunctionReductionGuesser::inferUnaryMinusFamily(const TypeFunctionInstanceType* instance)
 {
     LUAU_ASSERT(instance->typeArguments.size() == 1);
     TypeId opTy = follow(instance->typeArguments[0]);

Analysis/src/Unifier.cpp

@@ -454,11 +454,11 @@ void Unifier::tryUnify_(TypeId subTy, TypeId superTy, bool isFunctionCall, bool
     else if (isBlocked(log, superTy))
         blockedTypes.push_back(superTy);
 
-    if (log.get<TypeFamilyInstanceType>(superTy))
+    if (log.get<TypeFunctionInstanceType>(superTy))
-        ice("Unexpected TypeFamilyInstanceType superTy");
+        ice("Unexpected TypeFunctionInstanceType superTy");
 
-    if (log.get<TypeFamilyInstanceType>(subTy))
+    if (log.get<TypeFunctionInstanceType>(subTy))
-        ice("Unexpected TypeFamilyInstanceType subTy");
+        ice("Unexpected TypeFunctionInstanceType subTy");
 
     auto superFree = log.getMutable<FreeType>(superTy);
     auto subFree = log.getMutable<FreeType>(subTy);

Analysis/src/Unifier2.cpp

@@ -8,7 +8,7 @@
 #include "Luau/Type.h"
 #include "Luau/TypeArena.h"
 #include "Luau/TypeCheckLimits.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypePack.h"
 #include "Luau/TypeUtils.h"
@@ -76,13 +76,13 @@ static bool areCompatible(TypeId left, TypeId right)
 // returns `true` if `ty` is irressolvable and should be added to `incompleteSubtypes`.
 static bool isIrresolvable(TypeId ty)
 {
-    return get<BlockedType>(ty) || get<TypeFamilyInstanceType>(ty);
+    return get<BlockedType>(ty) || get<TypeFunctionInstanceType>(ty);
 }
 
 // returns `true` if `tp` is irressolvable and should be added to `incompleteSubtypes`.
 static bool isIrresolvable(TypePackId tp)
 {
-    return get<BlockedTypePack>(tp) || get<TypeFamilyInstanceTypePack>(tp);
+    return get<BlockedTypePack>(tp) || get<TypeFunctionInstanceTypePack>(tp);
 }
 
 Unifier2::Unifier2(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, NotNull<Scope> scope, NotNull<InternalErrorReporter> ice)

CodeGen/src/IrAnalysis.cpp

@@ -13,8 +13,6 @@
 
 #include <stddef.h>
 
-LUAU_FASTFLAGVARIABLE(LuauCodegenInstG, false)
-
 namespace Luau
 {
 namespace CodeGen
@@ -54,9 +52,7 @@ void updateUseCounts(IrFunction& function)
         checkOp(inst.d);
         checkOp(inst.e);
         checkOp(inst.f);
-
+        checkOp(inst.g);
-        if (FFlag::LuauCodegenInstG)
-            checkOp(inst.g);
     }
 }
 
@@ -100,9 +96,7 @@ void updateLastUseLocations(IrFunction& function, const std::vector<uint32_t>& s
             checkOp(inst.d);
             checkOp(inst.e);
             checkOp(inst.f);
-
+            checkOp(inst.g);
-            if (FFlag::LuauCodegenInstG)
-                checkOp(inst.g);
         }
     }
 }
@@ -137,11 +131,8 @@ uint32_t getNextInstUse(IrFunction& function, uint32_t targetInstIdx, uint32_t s
         if (inst.f.kind == IrOpKind::Inst && inst.f.index == targetInstIdx)
             return i;
 
-        if (FFlag::LuauCodegenInstG)
+        if (inst.g.kind == IrOpKind::Inst && inst.g.index == targetInstIdx)
-        {
+            return i;
-            if (inst.g.kind == IrOpKind::Inst && inst.g.index == targetInstIdx)
-                return i;
-        }
     }
 
     // There must be a next use since there is the last use location
@@ -179,9 +170,7 @@ std::pair<uint32_t, uint32_t> getLiveInOutValueCount(IrFunction& function, IrBlo
         checkOp(inst.d);
         checkOp(inst.e);
         checkOp(inst.f);
-
+        checkOp(inst.g);
-        if (FFlag::LuauCodegenInstG)
-            checkOp(inst.g);
     }
 
     return std::make_pair(liveIns, liveOuts);
@@ -505,9 +494,7 @@ static void computeCfgBlockEdges(IrFunction& function)
             checkOp(inst.d);
             checkOp(inst.e);
             checkOp(inst.f);
-
+            checkOp(inst.g);
-            if (FFlag::LuauCodegenInstG)
-                checkOp(inst.g);
         }
     }
 

CodeGen/src/IrBuilder.cpp

@@ -13,7 +13,6 @@
 
 #include <string.h>
 
-LUAU_FASTFLAG(LuauCodegenInstG)
 LUAU_FASTFLAG(LuauCodegenFastcall3)
 
 namespace Luau
@@ -641,9 +640,7 @@ void IrBuilder::clone(const IrBlock& source, bool removeCurrentTerminator)
         redirect(clone.d);
         redirect(clone.e);
         redirect(clone.f);
-
+        redirect(clone.g);
-        if (FFlag::LuauCodegenInstG)
-            redirect(clone.g);
 
         addUse(function, clone.a);
         addUse(function, clone.b);
@@ -651,18 +648,13 @@ void IrBuilder::clone(const IrBlock& source, bool removeCurrentTerminator)
         addUse(function, clone.d);
         addUse(function, clone.e);
         addUse(function, clone.f);
-
+        addUse(function, clone.g);
-        if (FFlag::LuauCodegenInstG)
-            addUse(function, clone.g);
 
         // Instructions that referenced the original will have to be adjusted to use the clone
         instRedir[index] = uint32_t(function.instructions.size());
 
         // Reconstruct the fresh clone
-        if (FFlag::LuauCodegenInstG)
+        inst(clone.cmd, clone.a, clone.b, clone.c, clone.d, clone.e, clone.f, clone.g);
-            inst(clone.cmd, clone.a, clone.b, clone.c, clone.d, clone.e, clone.f, clone.g);
-        else
-            inst(clone.cmd, clone.a, clone.b, clone.c, clone.d, clone.e, clone.f);
     }
 }
 
@@ -760,31 +752,11 @@ IrOp IrBuilder::inst(IrCmd cmd, IrOp a, IrOp b, IrOp c, IrOp d, IrOp e)
 
 IrOp IrBuilder::inst(IrCmd cmd, IrOp a, IrOp b, IrOp c, IrOp d, IrOp e, IrOp f)
 {
-    if (FFlag::LuauCodegenInstG)
+    return inst(cmd, a, b, c, d, e, f, {});
-    {
-        return inst(cmd, a, b, c, d, e, f, {});
-    }
-    else
-    {
-        uint32_t index = uint32_t(function.instructions.size());
-        function.instructions.push_back({cmd, a, b, c, d, e, f});
-
-        CODEGEN_ASSERT(!inTerminatedBlock);
-
-        if (isBlockTerminator(cmd))
-        {
-            function.blocks[activeBlockIdx].finish = index;
-            inTerminatedBlock = true;
-        }
-
-        return {IrOpKind::Inst, index};
-    }
 }
 
 IrOp IrBuilder::inst(IrCmd cmd, IrOp a, IrOp b, IrOp c, IrOp d, IrOp e, IrOp f, IrOp g)
 {
-    CODEGEN_ASSERT(FFlag::LuauCodegenInstG);
-
     uint32_t index = uint32_t(function.instructions.size());
     function.instructions.push_back({cmd, a, b, c, d, e, f, g});
 

CodeGen/src/IrDump.cpp

@@ -7,8 +7,6 @@
 
 #include <stdarg.h>
 
-LUAU_FASTFLAG(LuauCodegenInstG)
-
 namespace Luau
 {
 namespace CodeGen
@@ -419,9 +417,7 @@ void toString(IrToStringContext& ctx, const IrInst& inst, uint32_t index)
     checkOp(inst.d, ", ");
     checkOp(inst.e, ", ");
     checkOp(inst.f, ", ");
-
+    checkOp(inst.g, ", ");
-    if (FFlag::LuauCodegenInstG)
-        checkOp(inst.g, ", ");
 }
 
 void toString(IrToStringContext& ctx, const IrBlock& block, uint32_t index)
@@ -611,7 +607,7 @@ static RegisterSet getJumpTargetExtraLiveIn(IrToStringContext& ctx, const IrBloc
         op = inst.e;
     else if (inst.f.kind == IrOpKind::Block)
         op = inst.f;
-    else if (FFlag::LuauCodegenInstG && inst.g.kind == IrOpKind::Block)
+    else if (inst.g.kind == IrOpKind::Block)
         op = inst.g;
 
     if (op.kind == IrOpKind::Block && op.index < ctx.cfg.in.size())
@@ -897,9 +893,7 @@ std::string toDot(const IrFunction& function, bool includeInst)
             checkOp(inst.d);
             checkOp(inst.e);
             checkOp(inst.f);
-
+            checkOp(inst.g);
-            if (FFlag::LuauCodegenInstG)
-                checkOp(inst.g);
         }
     }
 

CodeGen/src/IrRegAllocA64.cpp

@@ -11,7 +11,6 @@
 #include <string.h>
 
 LUAU_FASTFLAGVARIABLE(DebugCodegenChaosA64, false)
-LUAU_FASTFLAG(LuauCodegenInstG)
 
 namespace Luau
 {
@@ -257,9 +256,7 @@ void IrRegAllocA64::freeLastUseRegs(const IrInst& inst, uint32_t index)
     checkOp(inst.d);
     checkOp(inst.e);
     checkOp(inst.f);
-
+    checkOp(inst.g);
-    if (FFlag::LuauCodegenInstG)
-        checkOp(inst.g);
 }
 
 void IrRegAllocA64::freeTempRegs()

CodeGen/src/IrRegAllocX64.cpp

@@ -6,8 +6,6 @@
 
 #include "EmitCommonX64.h"
 
-LUAU_FASTFLAG(LuauCodegenInstG)
-
 namespace Luau
 {
 namespace CodeGen
@@ -183,9 +181,7 @@ void IrRegAllocX64::freeLastUseRegs(const IrInst& inst, uint32_t instIdx)
     checkOp(inst.d);
     checkOp(inst.e);
     checkOp(inst.f);
-
+    checkOp(inst.g);
-    if (FFlag::LuauCodegenInstG)
-        checkOp(inst.g);
 }
 
 bool IrRegAllocX64::isLastUseReg(const IrInst& target, uint32_t instIdx) const

CodeGen/src/IrUtils.cpp

@@ -12,8 +12,6 @@
 #include <limits.h>
 #include <math.h>
 
-LUAU_FASTFLAG(LuauCodegenInstG)
-
 namespace Luau
 {
 namespace CodeGen
@@ -317,9 +315,7 @@ void kill(IrFunction& function, IrInst& inst)
     removeUse(function, inst.d);
     removeUse(function, inst.e);
     removeUse(function, inst.f);
-
+    removeUse(function, inst.g);
-    if (FFlag::LuauCodegenInstG)
-        removeUse(function, inst.g);
 
     inst.a = {};
     inst.b = {};
@@ -327,9 +323,7 @@ void kill(IrFunction& function, IrInst& inst)
     inst.d = {};
     inst.e = {};
     inst.f = {};
-
+    inst.g = {};
-    if (FFlag::LuauCodegenInstG)
-        inst.g = {};
 }
 
 void kill(IrFunction& function, uint32_t start, uint32_t end)
@@ -378,9 +372,7 @@ void replace(IrFunction& function, IrBlock& block, uint32_t instIdx, IrInst repl
     addUse(function, replacement.d);
     addUse(function, replacement.e);
     addUse(function, replacement.f);
-
+    addUse(function, replacement.g);
-    if (FFlag::LuauCodegenInstG)
-        addUse(function, replacement.g);
 
     // An extra reference is added so block will not remove itself
     block.useCount++;
@@ -403,9 +395,7 @@ void replace(IrFunction& function, IrBlock& block, uint32_t instIdx, IrInst repl
     removeUse(function, inst.d);
     removeUse(function, inst.e);
     removeUse(function, inst.f);
-
+    removeUse(function, inst.g);
-    if (FFlag::LuauCodegenInstG)
-        removeUse(function, inst.g);
 
     // Inherit existing use count (last use is skipped as it will be defined later)
     replacement.useCount = inst.useCount;
@@ -431,9 +421,7 @@ void substitute(IrFunction& function, IrInst& inst, IrOp replacement)
     removeUse(function, inst.d);
     removeUse(function, inst.e);
     removeUse(function, inst.f);
-
+    removeUse(function, inst.g);
-    if (FFlag::LuauCodegenInstG)
-        removeUse(function, inst.g);
 
     inst.a = replacement;
     inst.b = {};
@@ -441,9 +429,7 @@ void substitute(IrFunction& function, IrInst& inst, IrOp replacement)
     inst.d = {};
     inst.e = {};
     inst.f = {};
-
+    inst.g = {};
-    if (FFlag::LuauCodegenInstG)
-        inst.g = {};
 }
 
 void applySubstitutions(IrFunction& function, IrOp& op)
@@ -487,9 +473,7 @@ void applySubstitutions(IrFunction& function, IrInst& inst)
     applySubstitutions(function, inst.d);
     applySubstitutions(function, inst.e);
     applySubstitutions(function, inst.f);
-
+    applySubstitutions(function, inst.g);
-    if (FFlag::LuauCodegenInstG)
-        applySubstitutions(function, inst.g);
 }
 
 bool compare(double a, double b, IrCondition cond)

Sources.cmake

@@ -219,8 +219,8 @@ target_sources(Luau.Analysis PRIVATE
     Analysis/include/Luau/TypeChecker2.h
     Analysis/include/Luau/TypeCheckLimits.h
     Analysis/include/Luau/TypedAllocator.h
-    Analysis/include/Luau/TypeFamily.h
+    Analysis/include/Luau/TypeFunction.h
-    Analysis/include/Luau/TypeFamilyReductionGuesser.h
+    Analysis/include/Luau/TypeFunctionReductionGuesser.h
     Analysis/include/Luau/TypeFwd.h
     Analysis/include/Luau/TypeInfer.h
     Analysis/include/Luau/TypeOrPack.h
@@ -283,8 +283,8 @@ target_sources(Luau.Analysis PRIVATE
     Analysis/src/TypeAttach.cpp
     Analysis/src/TypeChecker2.cpp
     Analysis/src/TypedAllocator.cpp
-    Analysis/src/TypeFamily.cpp
+    Analysis/src/TypeFunction.cpp
-    Analysis/src/TypeFamilyReductionGuesser.cpp
+    Analysis/src/TypeFunctionReductionGuesser.cpp
     Analysis/src/TypeInfer.cpp
     Analysis/src/TypeOrPack.cpp
     Analysis/src/TypePack.cpp
@@ -454,7 +454,7 @@ if(TARGET Luau.UnitTest)
         tests/ToString.test.cpp
         tests/Transpiler.test.cpp
         tests/TxnLog.test.cpp
-        tests/TypeFamily.test.cpp
+        tests/TypeFunction.test.cpp
         tests/TypeInfer.aliases.test.cpp
         tests/TypeInfer.annotations.test.cpp
         tests/TypeInfer.anyerror.test.cpp

tests/IrBuilder.test.cpp

@@ -13,7 +13,6 @@
 #include <limits.h>
 
 LUAU_FASTFLAG(DebugLuauAbortingChecks)
-LUAU_FASTFLAG(LuauCodegenInstG)
 LUAU_FASTFLAG(LuauCodegenFastcall3)
 LUAU_FASTFLAG(LuauCodegenMathSign)
 
@@ -1123,8 +1122,6 @@ bb_0:
 
 TEST_CASE_FIXTURE(IrBuilderFixture, "BuiltinFastcallsMayInvalidateMemory")
 {
-    ScopedFastFlag luauCodegenInstG{FFlag::LuauCodegenInstG, true};
-
     IrOp block = build.block(IrBlockKind::Internal);
     IrOp fallback = build.block(IrBlockKind::Fallback);
 
@@ -2814,7 +2811,6 @@ bb_1:
 
 TEST_CASE_FIXTURE(IrBuilderFixture, "ExplicitUseOfRegisterInVarargSequence")
 {
-    ScopedFastFlag luauCodegenInstG{FFlag::LuauCodegenInstG, true};
     ScopedFastFlag luauCodegenFastcall3{FFlag::LuauCodegenFastcall3, true};
 
     IrOp entry = build.block(IrBlockKind::Internal);

tests/Subtyping.test.cpp

@@ -7,7 +7,7 @@
 #include "Luau/Subtyping.h"
 #include "Luau/Type.h"
 #include "Luau/TypePack.h"
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 
 #include "doctest.h"
 #include "Fixture.h"
@@ -73,7 +73,7 @@ struct SubtypeFixture : Fixture
     ScopePtr moduleScope{new Scope(rootScope)};
 
     Subtyping subtyping = mkSubtyping(rootScope);
-    BuiltinTypeFamilies builtinTypeFamilies{};
+    BuiltinTypeFunctions builtinTypeFunctions{};
 
     Subtyping mkSubtyping(const ScopePtr& scope)
     {
@@ -398,51 +398,51 @@ TEST_SUITE_BEGIN("Subtyping");
 TEST_IS_SUBTYPE(builtinTypes->numberType, builtinTypes->anyType);
 TEST_IS_NOT_SUBTYPE(builtinTypes->numberType, builtinTypes->stringType);
 
-TEST_CASE_FIXTURE(SubtypeFixture, "basic_reducible_sub_typefamily")
+TEST_CASE_FIXTURE(SubtypeFixture, "basic_reducible_sub_type_function")
 {
     // add<number, number> <: number
-    TypeId typeFamilyNum =
+    TypeId typeFunctionNum =
-        arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.addFamily}, {builtinTypes->numberType, builtinTypes->numberType}, {}});
+        arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.addFunc}, {builtinTypes->numberType, builtinTypes->numberType}, {}});
     TypeId superTy = builtinTypes->numberType;
-    SubtypingResult result = isSubtype(typeFamilyNum, superTy);
+    SubtypingResult result = isSubtype(typeFunctionNum, superTy);
     CHECK(result.isSubtype);
 }
 
-TEST_CASE_FIXTURE(SubtypeFixture, "basic_reducible_super_typefamily")
+TEST_CASE_FIXTURE(SubtypeFixture, "basic_reducible_super_type_function")
 {
     // number <: add<number, number> ~ number
-    TypeId typeFamilyNum =
+    TypeId typeFunctionNum =
-        arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.addFamily}, {builtinTypes->numberType, builtinTypes->numberType}, {}});
+        arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.addFunc}, {builtinTypes->numberType, builtinTypes->numberType}, {}});
     TypeId subTy = builtinTypes->numberType;
-    SubtypingResult result = isSubtype(subTy, typeFamilyNum);
+    SubtypingResult result = isSubtype(subTy, typeFunctionNum);
     CHECK(result.isSubtype);
 }
 
-TEST_CASE_FIXTURE(SubtypeFixture, "basic_irreducible_sub_typefamily")
+TEST_CASE_FIXTURE(SubtypeFixture, "basic_irreducible_sub_type_function")
 {
     // add<string, boolean> ~ never <: number
-    TypeId typeFamilyNum =
+    TypeId typeFunctionNum =
-        arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.addFamily}, {builtinTypes->stringType, builtinTypes->booleanType}, {}});
+        arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.addFunc}, {builtinTypes->stringType, builtinTypes->booleanType}, {}});
     TypeId superTy = builtinTypes->numberType;
-    SubtypingResult result = isSubtype(typeFamilyNum, superTy);
+    SubtypingResult result = isSubtype(typeFunctionNum, superTy);
     CHECK(result.isSubtype);
 }
 
-TEST_CASE_FIXTURE(SubtypeFixture, "basic_irreducible_super_typefamily")
+TEST_CASE_FIXTURE(SubtypeFixture, "basic_irreducible_super_type_function")
 {
     // number <\: add<string, boolean> ~ irreducible/never
-    TypeId typeFamilyNum =
+    TypeId typeFunctionNum =
-        arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.addFamily}, {builtinTypes->stringType, builtinTypes->booleanType}, {}});
+        arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.addFunc}, {builtinTypes->stringType, builtinTypes->booleanType}, {}});
     TypeId subTy = builtinTypes->numberType;
-    SubtypingResult result = isSubtype(subTy, typeFamilyNum);
+    SubtypingResult result = isSubtype(subTy, typeFunctionNum);
     CHECK(!result.isSubtype);
 }
 
-TEST_CASE_FIXTURE(SubtypeFixture, "basic_typefamily_with_generics")
+TEST_CASE_FIXTURE(SubtypeFixture, "basic_type_function_with_generics")
 {
     // <T,U>(x: T, x: U) -> add<T,U> <: (number, number) -> number
-    TypeId addFamily = arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.addFamily}, {genericT, genericU}, {}});
+    TypeId addTypeFunction = arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.addFunc}, {genericT, genericU}, {}});
-    FunctionType ft{{genericT, genericU}, {}, arena.addTypePack({genericT, genericU}), arena.addTypePack({addFamily})};
+    FunctionType ft{{genericT, genericU}, {}, arena.addTypePack({genericT, genericU}), arena.addTypePack({addTypeFunction})};
     TypeId functionType = arena.addType(std::move(ft));
     FunctionType superFt{arena.addTypePack({builtinTypes->numberType, builtinTypes->numberType}), arena.addTypePack({builtinTypes->numberType})};
     TypeId superFunction = arena.addType(std::move(superFt));
@@ -1292,7 +1292,7 @@ TEST_CASE_FIXTURE(SubtypeFixture, "subtyping_reasonings_to_follow_a_reduced_type
         builtinTypes->numberType, builtinTypes->stringType, builtinTypes->tableType, builtinTypes->threadType}});
     TypeId tblTy = tbl({{"depth", builtinTypes->unknownType}});
     TypeId combined = meet(longTy, tblTy);
-    TypeId subTy = arena.addType(TypeFamilyInstanceType{NotNull{&builtinTypeFamilies.unionFamily}, {combined, builtinTypes->neverType}, {}});
+    TypeId subTy = arena.addType(TypeFunctionInstanceType{NotNull{&builtinTypeFunctions.unionFunc}, {combined, builtinTypes->neverType}, {}});
     TypeId superTy = builtinTypes->neverType;
     SubtypingResult result = isSubtype(subTy, superTy);
     CHECK(!result.isSubtype);
@@ -1321,9 +1321,10 @@ TEST_CASE_FIXTURE(SubtypeFixture, "table_property")
 
     SubtypingResult result = isSubtype(subTy, superTy);
     CHECK(!result.isSubtype);
-    CHECK(result.reasoning == std::vector{SubtypingReasoning{/* subPath */ Path(TypePath::Property::read("X")),
+    REQUIRE(result.reasoning.size() == 1);
+    CHECK(*result.reasoning.begin() == SubtypingReasoning{/* subPath */ Path(TypePath::Property::read("X")),
                                   /* superPath */ Path(TypePath::Property::read("X")),
-                                  /* variance */ SubtypingVariance::Invariant}});
+                                  /* variance */ SubtypingVariance::Invariant});
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "table_indexers")
@@ -1394,10 +1395,11 @@ TEST_CASE_FIXTURE(SubtypeFixture, "fn_rets")
 
     SubtypingResult result = isSubtype(subTy, superTy);
     CHECK(!result.isSubtype);
-    CHECK(result.reasoning == std::vector{SubtypingReasoning{
+    REQUIRE(result.reasoning.size() == 1);
+    CHECK(*result.reasoning.begin() == SubtypingReasoning{
                                   /* subPath */ TypePath::PathBuilder().rets().index(0).build(),
                                   /* superPath */ TypePath::PathBuilder().rets().index(0).build(),
-                              }});
+                              });
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "fn_rets_tail")
@@ -1407,10 +1409,11 @@ TEST_CASE_FIXTURE(SubtypeFixture, "fn_rets_tail")
 
     SubtypingResult result = isSubtype(subTy, superTy);
     CHECK(!result.isSubtype);
-    CHECK(result.reasoning == std::vector{SubtypingReasoning{
+    REQUIRE(result.reasoning.size() == 1);
+    CHECK(*result.reasoning.begin() == SubtypingReasoning{
                                   /* subPath */ TypePath::PathBuilder().rets().tail().variadic().build(),
                                   /* superPath */ TypePath::PathBuilder().rets().tail().variadic().build(),
-                              }});
+                              });
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "nested_table_properties")
@@ -1420,11 +1423,12 @@ TEST_CASE_FIXTURE(SubtypeFixture, "nested_table_properties")
 
     SubtypingResult result = isSubtype(subTy, superTy);
     CHECK(!result.isSubtype);
-    CHECK(result.reasoning == std::vector{SubtypingReasoning{
+    REQUIRE(result.reasoning.size() == 1);
+    CHECK(*result.reasoning.begin() == SubtypingReasoning{
                                   /* subPath */ TypePath::PathBuilder().readProp("X").readProp("Y").readProp("Z").build(),
                                   /* superPath */ TypePath::PathBuilder().readProp("X").readProp("Y").readProp("Z").build(),
                                   /* variance */ SubtypingVariance::Invariant,
-                              }});
+                              });
 }
 
 TEST_CASE_FIXTURE(SubtypeFixture, "string_table_mt")

tests/TypeFunction.test.cpp

@@ -1,5 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/TypeFamily.h"
+#include "Luau/TypeFunction.h"
 
 #include "Luau/ConstraintSolver.h"
 #include "Luau/NotNull.h"
@@ -17,34 +17,34 @@ LUAU_DYNAMIC_FASTINT(LuauTypeFamilyApplicationCartesianProductLimit)
 
 struct FamilyFixture : Fixture
 {
-    TypeFamily swapFamily;
+    TypeFunction swapFamily;
 
     FamilyFixture()
         : Fixture(true, false)
     {
-        swapFamily = TypeFamily{/* name */ "Swap",
+        swapFamily = TypeFunction{/* name */ "Swap",
             /* reducer */
             [](TypeId instance, const std::vector<TypeId>& tys, const std::vector<TypePackId>& tps,
-                NotNull<TypeFamilyContext> ctx) -> TypeFamilyReductionResult<TypeId> {
+                NotNull<TypeFunctionContext> ctx) -> TypeFunctionReductionResult<TypeId> {
                 LUAU_ASSERT(tys.size() == 1);
                 TypeId param = follow(tys.at(0));
 
                 if (isString(param))
                 {
-                    return TypeFamilyReductionResult<TypeId>{ctx->builtins->numberType, false, {}, {}};
+                    return TypeFunctionReductionResult<TypeId>{ctx->builtins->numberType, false, {}, {}};
                 }
                 else if (isNumber(param))
                 {
-                    return TypeFamilyReductionResult<TypeId>{ctx->builtins->stringType, false, {}, {}};
+                    return TypeFunctionReductionResult<TypeId>{ctx->builtins->stringType, false, {}, {}};
                 }
-                else if (is<BlockedType>(param) || is<PendingExpansionType>(param) || is<TypeFamilyInstanceType>(param) ||
+                else if (is<BlockedType>(param) || is<PendingExpansionType>(param) || is<TypeFunctionInstanceType>(param) ||
                          (ctx->solver && ctx->solver->hasUnresolvedConstraints(param)))
                 {
-                    return TypeFamilyReductionResult<TypeId>{std::nullopt, false, {param}, {}};
+                    return TypeFunctionReductionResult<TypeId>{std::nullopt, false, {param}, {}};
                 }
                 else
                 {
-                    return TypeFamilyReductionResult<TypeId>{std::nullopt, true, {}, {}};
+                    return TypeFunctionReductionResult<TypeId>{std::nullopt, true, {}, {}};
                 }
             }};
 
@@ -54,12 +54,12 @@ struct FamilyFixture : Fixture
 
         ScopePtr globalScope = frontend.globals.globalScope;
         globalScope->exportedTypeBindings["Swap"] =
-            TypeFun{{genericT}, frontend.globals.globalTypes.addType(TypeFamilyInstanceType{NotNull{&swapFamily}, {t}, {}})};
+            TypeFun{{genericT}, frontend.globals.globalTypes.addType(TypeFunctionInstanceType{NotNull{&swapFamily}, {t}, {}})};
         freeze(frontend.globals.globalTypes);
     }
 };
 
-TEST_SUITE_BEGIN("TypeFamilyTests");
+TEST_SUITE_BEGIN("TypeFunctionTests");
 
 TEST_CASE_FIXTURE(FamilyFixture, "basic_type_family")
 {
@@ -80,7 +80,7 @@ TEST_CASE_FIXTURE(FamilyFixture, "basic_type_family")
     CHECK("number" == toString(requireTypeAlias("B")));
     CHECK("Swap<boolean>" == toString(requireTypeAlias("C")));
     CHECK("string" == toString(requireType("y")));
-    CHECK("Type family instance Swap<boolean> is uninhabited" == toString(result.errors[0]));
+    CHECK("Type function instance Swap<boolean> is uninhabited" == toString(result.errors[0]));
 };
 
 TEST_CASE_FIXTURE(FamilyFixture, "family_as_fn_ret")
@@ -99,7 +99,7 @@ TEST_CASE_FIXTURE(FamilyFixture, "family_as_fn_ret")
     CHECK("string" == toString(requireType("a")));
     CHECK("number" == toString(requireType("b")));
     CHECK("Swap<boolean>" == toString(requireType("c")));
-    CHECK("Type family instance Swap<boolean> is uninhabited" == toString(result.errors[0]));
+    CHECK("Type function instance Swap<boolean> is uninhabited" == toString(result.errors[0]));
 }
 
 TEST_CASE_FIXTURE(FamilyFixture, "family_as_fn_arg")
@@ -117,8 +117,8 @@ TEST_CASE_FIXTURE(FamilyFixture, "family_as_fn_arg")
     // FIXME: Can we constrain these to `never` or `unknown`?
     CHECK("a" == toString(requireType("a")));
     CHECK("a" == toString(requireType("b")));
-    CHECK("Type family instance Swap<a> is uninhabited" == toString(result.errors[0]));
+    CHECK("Type function instance Swap<a> is uninhabited" == toString(result.errors[0]));
-    CHECK("Type family instance Swap<a> is uninhabited" == toString(result.errors[1]));
+    CHECK("Type function instance Swap<a> is uninhabited" == toString(result.errors[1]));
 }
 
 TEST_CASE_FIXTURE(FamilyFixture, "resolve_deep_families")
@@ -148,7 +148,7 @@ TEST_CASE_FIXTURE(FamilyFixture, "unsolvable_family")
     LUAU_REQUIRE_ERROR_COUNT(2, result);
     for (size_t i = 0; i < 2; ++i)
     {
-        CHECK(toString(result.errors[i]) == "Type family instance Swap<a> is uninhabited");
+        CHECK(toString(result.errors[i]) == "Type function instance Swap<a> is uninhabited");
     }
 }
 
@@ -169,7 +169,7 @@ TEST_CASE_FIXTURE(FamilyFixture, "table_internal_families")
     CHECK(toString(requireType("b")) == "{number}");
     // FIXME: table types are constructing a trivial union here.
     CHECK(toString(requireType("c")) == "{Swap<boolean | boolean | boolean>}");
-    CHECK(toString(result.errors[0]) == "Type family instance Swap<boolean | boolean | boolean> is uninhabited");
+    CHECK(toString(result.errors[0]) == "Type function instance Swap<boolean | boolean | boolean> is uninhabited");
 }
 
 TEST_CASE_FIXTURE(FamilyFixture, "function_internal_families")
@@ -190,7 +190,7 @@ TEST_CASE_FIXTURE(FamilyFixture, "function_internal_families")
     CHECK(toString(requireType("a")) == "() -> string");
     CHECK(toString(requireType("b")) == "() -> number");
     CHECK(toString(requireType("c")) == "() -> Swap<boolean>");
-    CHECK(toString(result.errors[0]) == "Type family instance Swap<boolean> is uninhabited");
+    CHECK(toString(result.errors[0]) == "Type function instance Swap<boolean> is uninhabited");
 }
 
 TEST_CASE_FIXTURE(Fixture, "add_family_at_work")
@@ -212,8 +212,8 @@ TEST_CASE_FIXTURE(Fixture, "add_family_at_work")
     CHECK(toString(requireType("a")) == "number");
     CHECK(toString(requireType("b")) == "Add<number, string>");
     CHECK(toString(requireType("c")) == "Add<string, number>");
-    CHECK(toString(result.errors[0]) == "Type family instance Add<number, string> is uninhabited");
+    CHECK(toString(result.errors[0]) == "Type function instance Add<number, string> is uninhabited");
-    CHECK(toString(result.errors[1]) == "Type family instance Add<string, number> is uninhabited");
+    CHECK(toString(result.errors[1]) == "Type function instance Add<string, number> is uninhabited");
 }
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "cyclic_add_family_at_work")
@@ -284,7 +284,7 @@ TEST_CASE_FIXTURE(Fixture, "internal_families_raise_errors")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    CHECK(toString(result.errors[0]) == "Type family instance Add<a, b> depends on generic function parameters but does not appear in the function "
+    CHECK(toString(result.errors[0]) == "Type function instance Add<a, b> depends on generic function parameters but does not appear in the function "
                                         "signature; this construct cannot be type-checked at this time");
 }
 
@@ -301,7 +301,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_families_can_be_shadowed")
             return string.format("hi %s", f)
         end
 
-        -- this should still work totally fine (and use the real type family)
+        -- this should still work totally fine (and use the real type function)
         function plus(a, b)
             return a + b
         end
@@ -387,7 +387,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "keyof_type_family_errors_if_it_has_nontable_
         local function err(idx: KeysOfMyObject): "x" | "y" | "z" return idx end
     )");
 
-    // FIXME(CLI-95289): we should actually only report the type family being uninhabited error at its first use, I think?
+    // FIXME(CLI-95289): we should actually only report the type function being uninhabited error at its first use, I think?
     LUAU_REQUIRE_ERROR_COUNT(2, result);
     CHECK(toString(result.errors[0]) == "Type 'MyObject | boolean' does not have keys, so 'keyof<MyObject | boolean>' is invalid");
     CHECK(toString(result.errors[1]) == "Type 'MyObject | boolean' does not have keys, so 'keyof<MyObject | boolean>' is invalid");
@@ -513,7 +513,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "rawkeyof_type_family_errors_if_it_has_nontab
         local function err(idx: KeysOfMyObject): "x" | "y" | "z" return idx end
     )");
 
-    // FIXME(CLI-95289): we should actually only report the type family being uninhabited error at its first use, I think?
+    // FIXME(CLI-95289): we should actually only report the type function being uninhabited error at its first use, I think?
     LUAU_REQUIRE_ERROR_COUNT(2, result);
     CHECK(toString(result.errors[0]) == "Type 'MyObject | boolean' does not have keys, so 'rawkeyof<MyObject | boolean>' is invalid");
     CHECK(toString(result.errors[1]) == "Type 'MyObject | boolean' does not have keys, so 'rawkeyof<MyObject | boolean>' is invalid");
@@ -586,7 +586,7 @@ TEST_CASE_FIXTURE(ClassFixture, "keyof_type_family_errors_if_it_has_nonclass_par
         local function err(idx: KeysOfMyObject): "BaseMethod" | "BaseField" return idx end
     )");
 
-    // FIXME(CLI-95289): we should actually only report the type family being uninhabited error at its first use, I think?
+    // FIXME(CLI-95289): we should actually only report the type function being uninhabited error at its first use, I think?
     LUAU_REQUIRE_ERROR_COUNT(2, result);
     CHECK(toString(result.errors[0]) == "Type 'BaseClass | boolean' does not have keys, so 'keyof<BaseClass | boolean>' is invalid");
     CHECK(toString(result.errors[1]) == "Type 'BaseClass | boolean' does not have keys, so 'keyof<BaseClass | boolean>' is invalid");
@@ -757,7 +757,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "exceeded_distributivity_limits")
     )");
 
     LUAU_REQUIRE_ERROR_COUNT(1, result);
-    CHECK(get<UninhabitedTypeFamily>(result.errors[0]));
+    CHECK(get<UninhabitedTypeFunction>(result.errors[0]));
 }
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "didnt_quite_exceed_distributivity_limits")
@@ -1163,4 +1163,4 @@ TEST_CASE_FIXTURE(ClassFixture, "rawget_type_family_errors_w_classes")
     CHECK(toString(result.errors[0]) == "Property '\"BaseField\"' does not exist on type 'BaseClass'");
 }
 
-TEST_SUITE_END();
+TEST_SUITE_END();

tests/TypeInfer.anyerror.test.cpp

@@ -386,6 +386,20 @@ stat = stat and tonumber(stat) or stat
     LUAU_REQUIRE_NO_ERRORS(result);
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "table_of_any_calls")
+{
+    CheckResult result = check(R"(
+        local function testFunc(input: {any})
+        end
+
+        local v = {true}
+
+        testFunc(v)
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+}
+
 TEST_CASE_FIXTURE(Fixture, "intersection_of_any_can_have_props")
 {
     // *blocked-130* ~ hasProp any & ~(false?), "_status"

tests/TypeInfer.functions.test.cpp

@@ -2262,7 +2262,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "regex_benchmark_string_format_minimization")
     LUAU_REQUIRE_NO_ERRORS(result);
 }
 
-TEST_CASE_FIXTURE(BuiltinsFixture, "subgeneric_typefamily_super_monomorphic")
+TEST_CASE_FIXTURE(BuiltinsFixture, "subgeneric_type_function_super_monomorphic")
 {
     CheckResult result = check(R"(
 local a: (number, number) -> number = function(a, b) return a - b end
@@ -2747,5 +2747,21 @@ _ = _,{}
     )");
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "overload_resolution_crash_when_argExprs_is_smaller_than_type_args")
+{
+    CheckResult result = check(R"(
+--!strict
+local parseError
+type Set<T> = {[T]: any}
+local function captureDependencies(
+	saveToSet: Set<PubTypes.Dependency>,
+	callback: (...any) -> any,
+	...
+)
+	local data = table.pack(xpcall(callback, parseError, ...))
+    end
+)");
+}
+
 
 TEST_SUITE_END();

tests/TypeInfer.operators.test.cpp

@@ -264,7 +264,7 @@ TEST_CASE_FIXTURE(Fixture, "cannot_indirectly_compare_types_that_do_not_have_a_m
 
     if (FFlag::DebugLuauDeferredConstraintResolution)
     {
-        UninhabitedTypeFamily* utf = get<UninhabitedTypeFamily>(result.errors[0]);
+        UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
         REQUIRE_EQ(toString(utf->ty), "lt<a, b>");
     }
@@ -294,7 +294,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "cannot_indirectly_compare_types_that_do_not_
 
     if (FFlag::DebugLuauDeferredConstraintResolution)
     {
-        UninhabitedTypeFamily* utf = get<UninhabitedTypeFamily>(result.errors[0]);
+        UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
         REQUIRE_EQ(toString(utf->ty), "lt<M, M>");
     }
@@ -557,7 +557,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "typecheck_unary_minus")
     {
         LUAU_REQUIRE_ERROR_COUNT(2, result);
 
-        UninhabitedTypeFamily* utf = get<UninhabitedTypeFamily>(result.errors[0]);
+        UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
         CHECK_EQ(toString(utf->ty), "unm<bar>");
 
@@ -786,7 +786,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
 
     if (FFlag::DebugLuauDeferredConstraintResolution)
     {
-        UninhabitedTypeFamily* utf = get<UninhabitedTypeFamily>(result.errors[0]);
+        UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
         REQUIRE_EQ(toString(utf->ty), "lt<boolean, boolean>");
     }
@@ -817,7 +817,7 @@ TEST_CASE_FIXTURE(Fixture, "error_on_invalid_operand_types_to_relational_operato
 
     if (FFlag::DebugLuauDeferredConstraintResolution)
     {
-        UninhabitedTypeFamily* utf = get<UninhabitedTypeFamily>(result.errors[0]);
+        UninhabitedTypeFunction* utf = get<UninhabitedTypeFunction>(result.errors[0]);
         REQUIRE(utf);
         REQUIRE_EQ(toString(utf->ty), "lt<number | string, number | string>");
     }

tools/faillist.txt

@@ -246,18 +246,18 @@ TypeAliases.report_shadowed_aliases
 TypeAliases.type_alias_local_mutation
 TypeAliases.type_alias_local_rename
 TypeAliases.type_alias_of_an_imported_recursive_generic_type
-TypeFamilyTests.add_family_at_work
+TypeFunctionTests.add_family_at_work
-TypeFamilyTests.cyclic_add_family_at_work
+TypeFunctionTests.cyclic_add_family_at_work
-TypeFamilyTests.cyclic_concat_family_at_work
+TypeFunctionTests.cyclic_concat_family_at_work
-TypeFamilyTests.didnt_quite_exceed_distributivity_limits
+TypeFunctionTests.didnt_quite_exceed_distributivity_limits
-TypeFamilyTests.ensure_equivalence_with_distributivity
+TypeFunctionTests.ensure_equivalence_with_distributivity
-TypeFamilyTests.family_as_fn_arg
+TypeFunctionTests.family_as_fn_arg
-TypeFamilyTests.index_type_family_works_w_generic_types
+TypeFunctionTests.index_type_family_works_w_generic_types
-TypeFamilyTests.internal_families_raise_errors
+TypeFunctionTests.internal_families_raise_errors
-TypeFamilyTests.keyof_oss_crash_gh1161
+TypeFunctionTests.keyof_oss_crash_gh1161
-TypeFamilyTests.mul_family_with_union_of_multiplicatives
+TypeFunctionTests.mul_family_with_union_of_multiplicatives
-TypeFamilyTests.mul_family_with_union_of_multiplicatives_2
+TypeFunctionTests.mul_family_with_union_of_multiplicatives_2
-TypeFamilyTests.unsolvable_family
+TypeFunctionTests.unsolvable_family
 TypeInfer.be_sure_to_use_active_txnlog_when_evaluating_a_variadic_overload
 TypeInfer.check_type_infer_recursion_count
 TypeInfer.checking_should_not_ice
@@ -277,7 +277,6 @@ TypeInfer.tc_if_else_expressions_expected_type_3
 TypeInfer.type_infer_recursion_limit_no_ice
 TypeInfer.type_infer_recursion_limit_normalizer
 TypeInfer.unify_nearly_identical_recursive_types
-TypeInferAnyError.can_subscript_any
 TypeInferAnyError.for_in_loop_iterator_is_any
 TypeInferAnyError.for_in_loop_iterator_is_any2
 TypeInferAnyError.for_in_loop_iterator_is_any_pack
@@ -290,7 +289,6 @@ TypeInferClasses.class_type_mismatch_with_name_conflict
 TypeInferClasses.detailed_class_unification_error
 TypeInferClasses.indexable_classes
 TypeInferClasses.table_class_unification_reports_sane_errors_for_missing_properties
-TypeInferClasses.table_indexers_are_invariant
 TypeInferClasses.we_can_report_when_someone_is_trying_to_use_a_table_rather_than_a_class
 TypeInferFunctions.another_other_higher_order_function
 TypeInferFunctions.bidirectional_checking_of_callback_property