Sync to upstream/release/649 (#1489)

Author: aatxe

Analysis/include/Luau/BuiltinDefinitions.h

@@ -82,4 +82,16 @@ std::optional<Binding> tryGetGlobalBinding(GlobalTypes& globals, const std::stri
 Binding* tryGetGlobalBindingRef(GlobalTypes& globals, const std::string& name);
 TypeId getGlobalBinding(GlobalTypes& globals, const std::string& name);
 
+
+/** A number of built-in functions are magical enough that we need to match on them specifically by
+ * name when they are called. These are listed here to be used whenever necessary, instead of duplicating this logic repeatedly.
+ */
+
+bool matchSetMetatable(const AstExprCall& call);
+bool matchTableFreeze(const AstExprCall& call);
+bool matchAssert(const AstExprCall& call);
+
+// Returns `true` if the function should introduce typestate for its first argument.
+bool shouldTypestateForFirstArgument(const AstExprCall& call);
+
 } // namespace Luau

Analysis/include/Luau/Clone.h

@@ -22,6 +22,15 @@ struct CloneState
     SeenTypePacks seenTypePacks;
 };
 
+/** `shallowClone` will make a copy of only the _top level_ constructor of the type,
+ * while `clone` will make a deep copy of the entire type and its every component.
+ *
+ * Be mindful about which behavior you actually _want_.
+ */
+
+TypePackId shallowClone(TypePackId tp, TypeArena& dest, CloneState& cloneState);
+TypeId shallowClone(TypeId typeId, TypeArena& dest, CloneState& cloneState);
+
 TypePackId clone(TypePackId tp, TypeArena& dest, CloneState& cloneState);
 TypeId clone(TypeId tp, TypeArena& dest, CloneState& cloneState);
 TypeFun clone(const TypeFun& typeFun, TypeArena& dest, CloneState& cloneState);

Analysis/include/Luau/ConstraintGenerator.h

@@ -146,6 +146,8 @@ struct ConstraintGenerator
      */
     void visitModuleRoot(AstStatBlock* block);
 
+    void visitFragmentRoot(const ScopePtr& resumeScope, AstStatBlock* block);
+
 private:
     std::vector<std::vector<TypeId>> interiorTypes;
 

Analysis/include/Luau/ConstraintSolver.h

@@ -3,6 +3,7 @@
 #pragma once
 
 #include "Luau/Constraint.h"
+#include "Luau/DataFlowGraph.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Error.h"
 #include "Luau/Location.h"
@@ -69,6 +70,9 @@ struct ConstraintSolver
     NotNull<Scope> rootScope;
     ModuleName currentModuleName;
 
+    // The dataflow graph of the program, used in constraint generation and for magic functions.
+    NotNull<const DataFlowGraph> dfg;
+
     // Constraints that the solver has generated, rather than sourcing from the
     // scope tree.
     std::vector<std::unique_ptr<Constraint>> solverConstraints;
@@ -120,6 +124,7 @@ struct ConstraintSolver
         NotNull<ModuleResolver> moduleResolver,
         std::vector<RequireCycle> requireCycles,
         DcrLogger* logger,
+        NotNull<const DataFlowGraph> dfg,
         TypeCheckLimits limits
     );
 
@@ -167,9 +172,9 @@ struct ConstraintSolver
      */
     bool tryDispatch(NotNull<const Constraint> c, bool force);
 
-    bool tryDispatch(const SubtypeConstraint& c, NotNull<const Constraint> constraint, bool force);
-    bool tryDispatch(const PackSubtypeConstraint& c, NotNull<const Constraint> constraint, bool force);
-    bool tryDispatch(const GeneralizationConstraint& c, NotNull<const Constraint> constraint, bool force);
+    bool tryDispatch(const SubtypeConstraint& c, NotNull<const Constraint> constraint);
+    bool tryDispatch(const PackSubtypeConstraint& c, NotNull<const Constraint> constraint);
+    bool tryDispatch(const GeneralizationConstraint& c, NotNull<const Constraint> constraint);
     bool tryDispatch(const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
     bool tryDispatch(const NameConstraint& c, NotNull<const Constraint> constraint);
     bool tryDispatch(const TypeAliasExpansionConstraint& c, NotNull<const Constraint> constraint);
@@ -194,14 +199,14 @@ struct ConstraintSolver
     bool tryDispatch(const UnpackConstraint& c, NotNull<const Constraint> constraint);
     bool tryDispatch(const ReduceConstraint& c, NotNull<const Constraint> constraint, bool force);
     bool tryDispatch(const ReducePackConstraint& c, NotNull<const Constraint> constraint, bool force);
-    bool tryDispatch(const EqualityConstraint& c, NotNull<const Constraint> constraint, bool force);
+    bool tryDispatch(const EqualityConstraint& c, NotNull<const Constraint> constraint);
 
     // for a, ... in some_table do
     // also handles __iter metamethod
     bool tryDispatchIterableTable(TypeId iteratorTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
 
     // for a, ... in next_function, t, ... do
-    bool tryDispatchIterableFunction(TypeId nextTy, TypeId tableTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
+    bool tryDispatchIterableFunction(TypeId nextTy, TypeId tableTy, const IterableConstraint& c, NotNull<const Constraint> constraint);
 
     std::pair<std::vector<TypeId>, std::optional<TypeId>> lookupTableProp(
         NotNull<const Constraint> constraint,

Analysis/include/Luau/DataFlowGraph.h

@@ -35,6 +35,8 @@ struct DataFlowGraph
     DataFlowGraph& operator=(DataFlowGraph&&) = default;
 
     DefId getDef(const AstExpr* expr) const;
+    // Look up the definition optionally, knowing it may not be present.
+    std::optional<DefId> getDefOptional(const AstExpr* expr) const;
     // Look up for the rvalue def for a compound assignment.
     std::optional<DefId> getRValueDefForCompoundAssign(const AstExpr* expr) const;
 

Analysis/include/Luau/FragmentAutocomplete.h

@@ -12,6 +12,7 @@
 
 namespace Luau
 {
+struct FrontendOptions;
 
 struct FragmentAutocompleteAncestryResult
 {
@@ -29,15 +30,30 @@ struct FragmentParseResult
     std::unique_ptr<Allocator> alloc = std::make_unique<Allocator>();
 };
 
+struct FragmentTypeCheckResult
+{
+    ModulePtr incrementalModule = nullptr;
+    Scope* freshScope = nullptr;
+};
+
 FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* root, const Position& cursorPos);
 
 FragmentParseResult parseFragment(const SourceModule& srcModule, std::string_view src, const Position& cursorPos);
 
+FragmentTypeCheckResult typecheckFragment(
+    Frontend& frontend,
+    const ModuleName& moduleName,
+    const Position& cursorPos,
+    std::optional<FrontendOptions> opts,
+    std::string_view src
+);
+
 AutocompleteResult fragmentAutocomplete(
     Frontend& frontend,
     std::string_view src,
     const ModuleName& moduleName,
     Position& cursorPosition,
+    std::optional<FrontendOptions> opts,
     StringCompletionCallback callback
 );
 

Analysis/include/Luau/Instantiation.h

@@ -60,7 +60,7 @@ struct ReplaceGenerics : Substitution
 };
 
 // A substitution which replaces generic functions by monomorphic functions
-struct Instantiation : Substitution
+struct Instantiation final : Substitution
 {
     Instantiation(const TxnLog* log, TypeArena* arena, NotNull<BuiltinTypes> builtinTypes, TypeLevel level, Scope* scope)
         : Substitution(log, arena)

Analysis/include/Luau/Normalize.h

@@ -23,8 +23,6 @@ using ModulePtr = std::shared_ptr<Module>;
 
 bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
 bool isSubtype(TypePackId subTy, TypePackId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
-bool isConsistentSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
-bool isConsistentSubtype(TypePackId subTy, TypePackId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
 
 class TypeIds
 {
@@ -336,6 +334,7 @@ struct NormalizedType
 };
 
 
+using SeenTablePropPairs = Set<std::pair<TypeId, TypeId>, TypeIdPairHash>;
 
 class Normalizer
 {
@@ -390,7 +389,13 @@ class Normalizer
     void unionTablesWithTable(TypeIds& heres, TypeId there);
     void unionTables(TypeIds& heres, const TypeIds& theres);
     NormalizationResult unionNormals(NormalizedType& here, const NormalizedType& there, int ignoreSmallerTyvars = -1);
-    NormalizationResult unionNormalWithTy(NormalizedType& here, TypeId there, Set<TypeId>& seenSetTypes, int ignoreSmallerTyvars = -1);
+    NormalizationResult unionNormalWithTy(
+        NormalizedType& here,
+        TypeId there,
+        SeenTablePropPairs& seenTablePropPairs,
+        Set<TypeId>& seenSetTypes,
+        int ignoreSmallerTyvars = -1
+    );
 
     // ------- Negations
     std::optional<NormalizedType> negateNormal(const NormalizedType& here);
@@ -407,16 +412,26 @@ class Normalizer
     void intersectClassesWithClass(NormalizedClassType& heres, TypeId there);
     void intersectStrings(NormalizedStringType& here, const NormalizedStringType& there);
     std::optional<TypePackId> intersectionOfTypePacks(TypePackId here, TypePackId there);
-    std::optional<TypeId> intersectionOfTables(TypeId here, TypeId there, Set<TypeId>& seenSet);
-    void intersectTablesWithTable(TypeIds& heres, TypeId there, Set<TypeId>& seenSetTypes);
+    std::optional<TypeId> intersectionOfTables(TypeId here, TypeId there, SeenTablePropPairs& seenTablePropPairs, Set<TypeId>& seenSet);
+    void intersectTablesWithTable(TypeIds& heres, TypeId there, SeenTablePropPairs& seenTablePropPairs, Set<TypeId>& seenSetTypes);
     void intersectTables(TypeIds& heres, const TypeIds& theres);
     std::optional<TypeId> intersectionOfFunctions(TypeId here, TypeId there);
     void intersectFunctionsWithFunction(NormalizedFunctionType& heress, TypeId there);
     void intersectFunctions(NormalizedFunctionType& heress, const NormalizedFunctionType& theress);
-    NormalizationResult intersectTyvarsWithTy(NormalizedTyvars& here, TypeId there, Set<TypeId>& seenSetTypes);
+    NormalizationResult intersectTyvarsWithTy(
+        NormalizedTyvars& here,
+        TypeId there,
+        SeenTablePropPairs& seenTablePropPairs,
+        Set<TypeId>& seenSetTypes
+    );
     NormalizationResult intersectNormals(NormalizedType& here, const NormalizedType& there, int ignoreSmallerTyvars = -1);
-    NormalizationResult intersectNormalWithTy(NormalizedType& here, TypeId there, Set<TypeId>& seenSetTypes);
-    NormalizationResult normalizeIntersections(const std::vector<TypeId>& intersections, NormalizedType& outType, Set<TypeId>& seenSet);
+    NormalizationResult intersectNormalWithTy(NormalizedType& here, TypeId there, SeenTablePropPairs& seenTablePropPairs, Set<TypeId>& seenSetTypes);
+    NormalizationResult normalizeIntersections(
+        const std::vector<TypeId>& intersections,
+        NormalizedType& outType,
+        SeenTablePropPairs& seenTablePropPairs,
+        Set<TypeId>& seenSet
+    );
 
     // Check for inhabitance
     NormalizationResult isInhabited(TypeId ty);
@@ -426,7 +441,7 @@ class Normalizer
 
     // Check for intersections being inhabited
     NormalizationResult isIntersectionInhabited(TypeId left, TypeId right);
-    NormalizationResult isIntersectionInhabited(TypeId left, TypeId right, Set<TypeId>& seenSet);
+    NormalizationResult isIntersectionInhabited(TypeId left, TypeId right, SeenTablePropPairs& seenTablePropPairs, Set<TypeId>& seenSet);
 
     // -------- Convert back from a normalized type to a type
     TypeId typeFromNormal(const NormalizedType& norm);

Analysis/include/Luau/Type.h

@@ -806,6 +806,13 @@ struct Type final
     Type& operator=(const TypeVariant& rhs);
     Type& operator=(TypeVariant&& rhs);
 
+    Type(Type&&) = default;
+    Type& operator=(Type&&) = default;
+
+    Type clone() const;
+
+private:
+    Type(const Type&) = default;
     Type& operator=(const Type& rhs);
 };
 

Analysis/include/Luau/Unifier.h

@@ -179,7 +179,7 @@ struct Unifier
     bool occursCheck(TypePackId needle, TypePackId haystack, bool reversed);
     bool occursCheck(DenseHashSet<TypePackId>& seen, TypePackId needle, TypePackId haystack);
 
-    Unifier makeChildUnifier();
+    std::unique_ptr<Unifier> makeChildUnifier();
 
     void reportError(TypeError err);
     LUAU_NOINLINE void reportError(Location location, TypeErrorData data);