Sync to upstream/release/653

Analysis/include/Luau/ConstraintGenerator.h

@@ -295,11 +295,25 @@ struct ConstraintGenerator
     Inference check(const ScopePtr& scope, AstExprFunction* func, std::optional<TypeId> expectedType, bool generalize);
     Inference check(const ScopePtr& scope, AstExprUnary* unary);
     Inference check(const ScopePtr& scope, AstExprBinary* binary, std::optional<TypeId> expectedType);
+    Inference checkAstExprBinary(
+        const ScopePtr& scope,
+        const Location& location,
+        AstExprBinary::Op op,
+        AstExpr* left,
+        AstExpr* right,
+        std::optional<TypeId> expectedType
+    );
     Inference check(const ScopePtr& scope, AstExprIfElse* ifElse, std::optional<TypeId> expectedType);
     Inference check(const ScopePtr& scope, AstExprTypeAssertion* typeAssert);
     Inference check(const ScopePtr& scope, AstExprInterpString* interpString);
     Inference check(const ScopePtr& scope, AstExprTable* expr, std::optional<TypeId> expectedType);
-    std::tuple<TypeId, TypeId, RefinementId> checkBinary(const ScopePtr& scope, AstExprBinary* binary, std::optional<TypeId> expectedType);
+    std::tuple<TypeId, TypeId, RefinementId> checkBinary(
+        const ScopePtr& scope,
+        AstExprBinary::Op op,
+        AstExpr* left,
+        AstExpr* right,
+        std::optional<TypeId> expectedType
+    );
 
     void visitLValue(const ScopePtr& scope, AstExpr* expr, TypeId rhsType);
     void visitLValue(const ScopePtr& scope, AstExprLocal* local, TypeId rhsType);

Analysis/include/Luau/ConstraintSolver.h

@@ -59,6 +59,25 @@ struct HashInstantiationSignature
     size_t operator()(const InstantiationSignature& signature) const;
 };
 
+
+struct TablePropLookupResult
+{
+    // What types are we blocked on for determining this type?
+    std::vector<TypeId> blockedTypes;
+    // The type of the property (if we were able to determine it).
+    std::optional<TypeId> propType;
+    // Whether or not this is _definitely_ derived as the result of an indexer.
+    // We use this to determine whether or not code like:
+    //
+    //   t.lol = nil;
+    //
+    // ... is legal. If `t: { [string]: ~nil }` then this is legal as
+    // there's no guarantee on whether "lol" specifically exists.
+    // However, if `t: { lol: ~nil }`, then we cannot allow assignment as
+    // that would remove "lol" from the table entirely.
+    bool isIndex = false;
+};
+
 struct ConstraintSolver
 {
     NotNull<TypeArena> arena;
@@ -211,15 +230,16 @@ struct ConstraintSolver
     // for a, ... in next_function, t, ... do
     bool tryDispatchIterableFunction(TypeId nextTy, TypeId tableTy, const IterableConstraint& c, NotNull<const Constraint> constraint);
 
-    std::pair<std::vector<TypeId>, std::optional<TypeId>> lookupTableProp(
+    TablePropLookupResult lookupTableProp(
         NotNull<const Constraint> constraint,
         TypeId subjectType,
         const std::string& propName,
         ValueContext context,
         bool inConditional = false,
         bool suppressSimplification = false
     );
-    std::pair<std::vector<TypeId>, std::optional<TypeId>> lookupTableProp(
+
+    TablePropLookupResult lookupTableProp(
         NotNull<const Constraint> constraint,
         TypeId subjectType,
         const std::string& propName,

Analysis/include/Luau/DataFlowGraph.h

@@ -84,7 +84,6 @@ struct DfgScope
 
     DfgScope* parent;
     ScopeType scopeType;
-    Location location;
 
     using Bindings = DenseHashMap<Symbol, const Def*>;
     using Props = DenseHashMap<const Def*, std::unordered_map<std::string, const Def*>>;
@@ -156,7 +155,7 @@ struct DataFlowGraphBuilder
     DenseHashMap<Symbol, FunctionCapture> captures{Symbol{}};
     void resolveCaptures();
 
-    DfgScope* makeChildScope(Location loc, DfgScope::ScopeType scopeType = DfgScope::Linear);
+    DfgScope* makeChildScope(DfgScope::ScopeType scopeType = DfgScope::Linear);
 
     void join(DfgScope* p, DfgScope* a, DfgScope* b);
     void joinBindings(DfgScope* p, const DfgScope& a, const DfgScope& b);

Analysis/include/Luau/Instantiation2.h

@@ -53,7 +53,7 @@ struct Replacer : Substitution
 };
 
 // A substitution which replaces generic functions by monomorphic functions
-struct Instantiation2 : Substitution
+struct Instantiation2 final : Substitution
 {
     // Mapping from generic types to free types to be used in instantiation.
     DenseHashMap<TypeId, TypeId> genericSubstitutions{nullptr};

Analysis/include/Luau/Module.h

@@ -135,9 +135,6 @@ struct Module
 
     TypePackId returnType = nullptr;
     std::unordered_map<Name, TypeFun> exportedTypeBindings;
-    // We also need to keep DFG data alive between runs
-    std::shared_ptr<DataFlowGraph> dataFlowGraph = nullptr;
-    std::vector<std::unique_ptr<DfgScope>> dfgScopes;
 
     bool hasModuleScope() const;
     ScopePtr getModuleScope() const;

Analysis/include/Luau/Type.h

@@ -762,7 +762,7 @@ struct NegationType
     TypeId ty;
 };
 
-using ErrorType = Unifiable::Error;
+using ErrorType = Unifiable::Error<TypeId>;
 
 using TypeVariant = Unifiable::Variant<
     TypeId,

Analysis/include/Luau/TypePack.h

@@ -52,7 +52,7 @@ struct GenericTypePack
 };
 
 using BoundTypePack = Unifiable::Bound<TypePackId>;
-using ErrorTypePack = Unifiable::Error;
+using ErrorTypePack = Unifiable::Error<TypePackId>;
 
 using TypePackVariant =
     Unifiable::Variant<TypePackId, FreeTypePack, GenericTypePack, TypePack, VariadicTypePack, BlockedTypePack, TypeFunctionInstanceTypePack>;

Analysis/include/Luau/Unifiable.h

@@ -3,6 +3,7 @@
 
 #include "Luau/Variant.h"
 
+#include <optional>
 #include <string>
 
 namespace Luau
@@ -94,19 +95,29 @@ struct Bound
     Id boundTo;
 };
 
+template<typename Id>
 struct Error
 {
     // This constructor has to be public, since it's used in Type and TypePack,
     // but shouldn't be called directly. Please use errorRecoveryType() instead.
-    Error();
+    explicit Error();
+
+    explicit Error(Id synthetic)
+        : synthetic{synthetic}
+    {
+    }
 
     int index;
 
+    // This is used to create an error that can be rendered out using this field
+    // as appropriate metadata for communicating it to the user.
+    std::optional<Id> synthetic;
+
 private:
     static int nextIndex;
 };
 
 template<typename Id, typename... Value>
-using Variant = Luau::Variant<Bound<Id>, Error, Value...>;
+using Variant = Luau::Variant<Bound<Id>, Error<Id>, Value...>;
 
 } // namespace Luau::Unifiable

Analysis/include/Luau/VisitType.h

@@ -10,7 +10,6 @@
 #include "Type.h"
 
 LUAU_FASTINT(LuauVisitRecursionLimit)
-LUAU_FASTFLAG(LuauBoundLazyTypes2)
 LUAU_FASTFLAG(LuauSolverV2)
 
 namespace Luau
@@ -190,7 +189,7 @@ struct GenericTypeVisitor
     {
         return visit(tp);
     }
-    virtual bool visit(TypePackId tp, const Unifiable::Error& etp)
+    virtual bool visit(TypePackId tp, const ErrorTypePack& etp)
     {
         return visit(tp);
     }
@@ -461,7 +460,7 @@ struct GenericTypeVisitor
         else if (auto gtv = get<GenericTypePack>(tp))
             visit(tp, *gtv);
 
-        else if (auto etv = get<Unifiable::Error>(tp))
+        else if (auto etv = get<ErrorTypePack>(tp))
             visit(tp, *etv);
 
         else if (auto pack = get<TypePack>(tp))

Analysis/src/Clone.cpp

@@ -257,8 +257,7 @@ class TypeCloner
             LUAU_ASSERT(!"Item holds neither TypeId nor TypePackId when enqueuing its children?");
     }
 
-    // ErrorType and ErrorTypePack is an alias to this type.
-    void cloneChildren(Unifiable::Error* t)
+    void cloneChildren(ErrorType* t)
     {
         // noop.
     }
@@ -428,6 +427,11 @@ class TypeCloner
         t->boundTo = shallowClone(t->boundTo);
     }
 
+    void cloneChildren(ErrorTypePack* t)
+    {
+        // noop.
+    }
+
     void cloneChildren(VariadicTypePack* t)
     {
         t->ty = shallowClone(t->ty);