Merge pull request swiftlang#84339 from slavapestov/better-prepared-overloads

Sema: Better prepared overloads

Author: slavapestov

include/swift/Sema/ConstraintSystem.h

@@ -3068,7 +3068,7 @@ class ConstraintSystem {
     return nullptr;
   }
 
-  TypeBase* getFavoredType(Expr *E) {
+  TypeBase *getFavoredType(Expr *E) {
     assert(E != nullptr);
     return this->FavoredTypes[E];
   }
@@ -3082,95 +3082,46 @@ class ConstraintSystem {
   ///
   /// The side tables are used through the expression type checker to avoid
   /// mutating nodes until we know we have successfully type-checked them.
-  void setType(ASTNode node, Type type) {
-    ASSERT(!node.isNull() && "Cannot set type information on null node");
-    ASSERT(type && "Expected non-null type");
-
-    // Record the type.
-    Type &entry = NodeTypes[node];
-    Type oldType = entry;
-    entry = type;
-
-    if (oldType.getPointer() != type.getPointer()) {
-      // Record the fact that we assigned a type to this node.
-      if (solverState)
-        recordChange(SolverTrail::Change::RecordedNodeType(node, oldType));
-    }
-  }
+  void setType(ASTNode node, Type type,
+               PreparedOverloadBuilder *preparedOverload=nullptr);
 
   /// Undo the above change.
-  void restoreType(ASTNode node, Type oldType) {
-    ASSERT(!node.isNull() && "Cannot set type information on null node");
-
-    if (oldType) {
-      auto found = NodeTypes.find(node);
-      ASSERT(found != NodeTypes.end());
-      found->second = oldType;
-    } else {
-      bool erased = NodeTypes.erase(node);
-      ASSERT(erased);
-    }
-  }
+  void restoreType(ASTNode node, Type oldType);
 
   /// Check to see if we have a type for a node.
   bool hasType(ASTNode node) const {
-    assert(!node.isNull() && "Expected non-null node");
+    ASSERT(!node.isNull() && "Expected non-null node");
     return NodeTypes.count(node) > 0;
   }
 
   /// Set the type in our type map for a given expression. The side
   /// map is used throughout the expression type checker in order to
   /// avoid mutating expressions until we know we have successfully
   /// type-checked them.
-  void setType(const KeyPathExpr *KP, unsigned I, Type T) {
-    ASSERT(KP && "Expected non-null key path parameter!");
-    ASSERT(T && "Expected non-null type!");
-
-    Type &entry = KeyPathComponentTypes[{KP, I}];
-    Type oldType = entry;
-    entry = T;
+  void setType(const KeyPathExpr *KP, unsigned I, Type T);
 
-    if (oldType.getPointer() != T.getPointer()) {
-      if (solverState) {
-        recordChange(
-          SolverTrail::Change::RecordedKeyPathComponentType(
-            KP, I, oldType));
-      }
-    }
-  }
-
-  void restoreType(const KeyPathExpr *KP, unsigned I, Type T) {
-    ASSERT(KP && "Expected non-null key path parameter!");
-
-    if (T) {
-      auto found = KeyPathComponentTypes.find({KP, I});
-      ASSERT(found != KeyPathComponentTypes.end());
-      found->second = T;
-    } else {
-      bool erased = KeyPathComponentTypes.erase({KP, I});
-      ASSERT(erased);
-    }
-  }
+  void restoreType(const KeyPathExpr *KP, unsigned I, Type T);
 
   bool hasType(const KeyPathExpr *KP, unsigned I) const {
-    assert(KP && "Expected non-null key path parameter!");
+    ASSERT(KP && "Expected non-null key path parameter!");
     return KeyPathComponentTypes.find(std::make_pair(KP, I))
               != KeyPathComponentTypes.end();
   }
 
   /// Get the type for an node.
   Type getType(ASTNode node) const {
-    assert(hasType(node) && "Expected type to have been set!");
-    // FIXME: lvalue differences
-    //    assert((!E->getType() ||
-    //            E->getType()->isEqual(ExprTypes.find(E)->second)) &&
-    //           "Mismatched types!");
-    return NodeTypes.find(node)->second;
+    ASSERT(!node.isNull() && "Expected non-null node");
+    auto found = NodeTypes.find(node);
+    ASSERT(found != NodeTypes.end() && "Expected type to have been set!");
+    return found->second;
   }
 
   Type getType(const KeyPathExpr *KP, unsigned I) const {
-    assert(hasType(KP, I) && "Expected type to have been set!");
-    return KeyPathComponentTypes.find(std::make_pair(KP, I))->second;
+    ASSERT(KP && "Expected non-null key path parameter!");
+    auto found = KeyPathComponentTypes.find(std::make_pair(KP, I));
+    ASSERT(found != KeyPathComponentTypes.end() &&
+           "Expected type to have been set!");
+    return found->second;
   }
 
   /// Retrieve the type of the node, if known.
@@ -3182,11 +3133,6 @@ class ConstraintSystem {
     return known->second;
   }
 
-  /// Retrieve type of the given declaration to be used in
-  /// constraint system, this is better than calling `getType()`
-  /// directly because it accounts of constraint system flags.
-  Type getVarType(const VarDecl *var);
-
   /// Cache the type of the expression argument and return that same
   /// argument.
   template <typename T>
@@ -3795,7 +3741,7 @@ class ConstraintSystem {
   /// Add a constraint that binds an overload set to a specific choice.
   void addBindOverloadConstraint(Type boundTy, OverloadChoice choice,
                                  ConstraintLocator *locator, DeclContext *useDC) {
-    resolveOverload(locator, boundTy, choice, useDC,
+    resolveOverload(choice, useDC, locator, boundTy,
                     /*preparedOverload=*/nullptr);
   }
 
@@ -4437,24 +4383,18 @@ class ConstraintSystem {
   FunctionType *adjustFunctionTypeForConcurrency(
       FunctionType *fnType, Type baseType, ValueDecl *decl, DeclContext *dc,
       unsigned numApplies, bool isMainDispatchQueue,
-      ArrayRef<OpenedType> replacements, ConstraintLocatorBuilder locator,
-      PreparedOverloadBuilder *preparedOverload);
+      bool openGlobalActorType, ConstraintLocatorBuilder locator);
 
   /// Retrieve the type of a reference to the given value declaration.
   ///
   /// For references to polymorphic function types, this routine "opens up"
   /// the type by replacing each instance of an archetype with a fresh type
   /// variable.
   ///
-  /// \param decl The declarations whose type is being computed.
-  ///
   /// \returns a description of the type of this declaration reference.
   DeclReferenceType getTypeOfReference(
-                          ValueDecl *decl,
-                          FunctionRefInfo functionRefInfo,
-                          ConstraintLocatorBuilder locator,
-                          DeclContext *useDC,
-                          PreparedOverloadBuilder *preparedOverload);
+      OverloadChoice choice, DeclContext *useDC, ConstraintLocatorBuilder locator,
+      PreparedOverloadBuilder *preparedOverload);
 
   /// Retrieve the type of a reference to the given value declaration,
   /// as a member with a base of the given type.
@@ -4463,15 +4403,10 @@ class ConstraintSystem {
   /// this routine "opens up" the type by replacing each instance of a generic
   /// parameter with a fresh type variable.
   ///
-  /// \param isDynamicLookup Indicates that this declaration was found via
-  /// dynamic lookup.
-  ///
   /// \returns a description of the type of this declaration reference.
   DeclReferenceType getTypeOfMemberReference(
-      Type baseTy, ValueDecl *decl, DeclContext *useDC, bool isDynamicLookup,
-      FunctionRefInfo functionRefInfo, ConstraintLocator *locator,
-      SmallVectorImpl<OpenedType> *replacements = nullptr,
-      PreparedOverloadBuilder *preparedOverload = nullptr);
+      OverloadChoice choice, DeclContext *useDC, ConstraintLocator *locator,
+      PreparedOverloadBuilder *preparedOverload);
 
   /// Retrieve a list of generic parameter types solver has "opened" (replaced
   /// with a type variable) at the given location.
@@ -4483,7 +4418,25 @@ class ConstraintSystem {
   }
 
 private:
-  DeclReferenceType getTypeOfMemberTypeReference(
+  /// \returns The opened type and the thrown error type.
+  std::pair<Type, Type> getTypeOfReferencePre(
+       OverloadChoice choice, DeclContext *useDC, ConstraintLocatorBuilder locator,
+       PreparedOverloadBuilder *preparedOverload);
+
+  DeclReferenceType getTypeOfReferencePost(
+       OverloadChoice choice, DeclContext *useDC, ConstraintLocatorBuilder locator,
+       Type openedType, Type thrownErrorType);
+
+  /// \returns the opened type and the thrown error type.
+  std::pair<Type, Type> getTypeOfMemberReferencePre(
+      OverloadChoice choice, DeclContext *useDC, ConstraintLocator *locator,
+      PreparedOverloadBuilder *preparedOverload);
+
+  DeclReferenceType getTypeOfMemberReferencePost(
+      OverloadChoice choice, DeclContext *useDC, ConstraintLocator *locator,
+      Type openedType, Type thrownErrorType);
+
+  Type getTypeOfMemberTypeReference(
       Type baseObjTy, TypeDecl *typeDecl, ConstraintLocator *locator,
       PreparedOverloadBuilder *preparedOverload);
 
@@ -4513,8 +4466,7 @@ class ConstraintSystem {
   /// determine the reference type of the member reference.
   Type getMemberReferenceTypeFromOpenedType(
       Type type, Type baseObjTy, ValueDecl *value,
-      ConstraintLocator *locator, bool hasAppliedSelf, bool isDynamicLookup,
-      ArrayRef<OpenedType> replacements);
+      ConstraintLocator *locator, bool hasAppliedSelf, bool isDynamicLookup);
 
   /// Add the constraints needed to bind an overload's type variable.
   void bindOverloadType(const SelectedOverload &overload, Type boundType,
@@ -4918,26 +4870,31 @@ class ConstraintSystem {
                               SelectedOverload choice);
 
   /// Build and allocate a prepared overload in the solver arena.
-  PreparedOverload *prepareOverload(ConstraintLocator *locator,
-                                    OverloadChoice choice,
-                                    DeclContext *useDC);
+  PreparedOverload *prepareOverload(OverloadChoice choice,
+                                    DeclContext *useDC,
+                                    ConstraintLocator *locator);
 
   /// Populate the prepared overload with all type variables and constraints
   /// that are to be introduced into the constraint system when this choice
   /// is taken.
-  DeclReferenceType
-  prepareOverloadImpl(ConstraintLocator *locator,
-                      OverloadChoice choice,
+  ///
+  /// Returns a pair consisting of the opened type, and the thrown error type.
+  ///
+  /// FIXME: As a transitional mechanism, if preparedOverload is nullptr, this
+  /// immediately performs all operations.
+  std::pair<Type, Type>
+  prepareOverloadImpl(OverloadChoice choice,
                       DeclContext *useDC,
+                      ConstraintLocator *locator,
                       PreparedOverloadBuilder *preparedOverload);
 
   void replayChanges(
       ConstraintLocator *locator,
       PreparedOverload *preparedOverload);
 
   /// Resolve the given overload set to the given choice.
-  void resolveOverload(ConstraintLocator *locator, Type boundType,
-                       OverloadChoice choice, DeclContext *useDC,
+  void resolveOverload(OverloadChoice choice, DeclContext *useDC,
+                       ConstraintLocator *locator, Type boundType,
                        PreparedOverload *preparedOverload);
 
   /// Simplify a type, by replacing type variables with either their

include/swift/Sema/OverloadChoice.h

@@ -126,20 +126,19 @@ class OverloadChoice {
   /// FIXME: This needs three bits. Can we pack them somewhere?
   FunctionRefInfo TheFunctionRefInfo = FunctionRefInfo::unappliedBaseName();
 
-public:
-  OverloadChoice() : BaseAndDeclKind(nullptr, 0), DeclOrKind() {}
-
   OverloadChoice(Type base, ValueDecl *value,
                  FunctionRefInfo functionRefInfo)
     : BaseAndDeclKind(base, 0),
       TheFunctionRefInfo(functionRefInfo) {
-    assert(!base || !base->hasTypeParameter());
     assert((reinterpret_cast<uintptr_t>(value) & (uintptr_t)0x03) == 0 &&
            "Badly aligned decl");
 
     DeclOrKind = value;
   }
 
+public:
+  OverloadChoice() : BaseAndDeclKind(nullptr, 0), DeclOrKind() {}
+
   OverloadChoice(Type base, OverloadChoiceKind kind)
       : BaseAndDeclKind(base, 0), DeclOrKind(uint32_t(kind)) {
     assert(base && "Must have a base type for overload choice");
@@ -162,6 +161,22 @@ class OverloadChoice {
            BaseAndDeclKind.getInt() == 0 && DeclOrKind.isNull();
   }
 
+  /// Retrieve an overload choice for a declaration that was found via
+  /// unqualified lookup.
+  static OverloadChoice getDecl(ValueDecl *value,
+                                FunctionRefInfo functionRefInfo) {
+    return OverloadChoice(Type(), value, functionRefInfo);
+  }
+
+
+  /// Retrieve an overload choice for a declaration that was found via
+  /// qualified lookup.
+  static OverloadChoice getDecl(Type base, ValueDecl *value,
+                                FunctionRefInfo functionRefInfo) {
+    ASSERT(!base->hasTypeParameter());
+    return OverloadChoice(base, value, functionRefInfo);
+  }
+
   /// Retrieve an overload choice for a declaration that was found via
   /// dynamic lookup.
   static OverloadChoice getDeclViaDynamic(Type base, ValueDecl *value,