AST: Consolidate inherited type resolution.

Move evaulation of `InheritedTypeRequest` into the `InheritedTypes` wrapper.
NFC.

Author: tshortli

include/swift/AST/Decl.h

@@ -35,6 +35,7 @@
 #include "swift/AST/RequirementSignature.h"
 #include "swift/AST/StorageImpl.h"
 #include "swift/AST/TypeAlignments.h"
+#include "swift/AST/TypeResolutionStage.h"
 #include "swift/AST/TypeWalker.h"
 #include "swift/AST/Types.h"
 #include "swift/Basic/ArrayRefView.h"
@@ -1572,7 +1573,11 @@ class InheritedTypes {
   /// given index.
   TypeRepr *getTypeRepr(unsigned i) const { return Entries[i].getTypeRepr(); }
 
-  /// Returns the array of inherited type entries.
+  /// Returns the `Type` for the entry of the inheritance clause at the given
+  /// index, resolved at the given stage, or `Type()` if resolution fails.
+  Type getResolvedType(unsigned i, TypeResolutionStage stage =
+                                       TypeResolutionStage::Interface) const;
+
   /// Returns the underlying array of inherited type entries.
   ///
   /// NOTE: The `Type` associated with an entry may not be resolved yet.

lib/AST/Decl.cpp

@@ -1559,6 +1559,15 @@ InheritedTypes::InheritedTypes(const ExtensionDecl *extensionDecl)
   Entries = extensionDecl->Inherited;
 }
 
+Type InheritedTypes::getResolvedType(unsigned i,
+                                     TypeResolutionStage stage) const {
+  ASTContext &ctx = Decl.is<const ExtensionDecl *>()
+                        ? Decl.get<const ExtensionDecl *>()->getASTContext()
+                        : Decl.get<const TypeDecl *>()->getASTContext();
+  return evaluateOrDefault(ctx.evaluator, InheritedTypeRequest{Decl, i, stage},
+                           Type());
+}
+
 ExtensionDecl::ExtensionDecl(SourceLoc extensionLoc,
                              TypeRepr *extendedType,
                              ArrayRef<InheritedEntry> inherited,

lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -729,17 +729,14 @@ void swift::rewriting::realizeInheritedRequirements(
     TypeDecl *decl, Type type, bool shouldInferRequirements,
     SmallVectorImpl<StructuralRequirement> &result,
     SmallVectorImpl<RequirementError> &errors) {
-  auto &ctx = decl->getASTContext();
   auto inheritedTypes = decl->getInherited();
   auto *dc = decl->getInnermostDeclContext();
   auto *moduleForInference = dc->getParentModule();
 
-  for (unsigned index : inheritedTypes.getIndices()) {
-    Type inheritedType
-      = evaluateOrDefault(ctx.evaluator,
-                          InheritedTypeRequest{decl, index,
-                          TypeResolutionStage::Structural},
-                          Type());
+  for (auto index : inheritedTypes.getIndices()) {
+    Type inheritedType =
+        inheritedTypes.getResolvedType(index, TypeResolutionStage::Structural);
+
     if (!inheritedType) continue;
 
     // Ignore trivially circular protocol refinement (protocol P : P)

lib/Sema/TypeCheckAccess.cpp

@@ -918,12 +918,9 @@ class AccessControlChecker : public AccessControlCheckerBase,
     DescriptiveDeclKind declKind = DescriptiveDeclKind::Protocol;
 
     // FIXME: Hack to ensure that we've computed the types involved here.
-    ASTContext &ctx = proto->getASTContext();
-    for (unsigned i : proto->getInherited().getIndices()) {
-      (void)evaluateOrDefault(ctx.evaluator,
-                              InheritedTypeRequest{
-                                proto, i, TypeResolutionStage::Interface},
-                              Type());
+    auto inheritedTypes = proto->getInherited();
+    for (auto i : inheritedTypes.getIndices()) {
+      (void)inheritedTypes.getResolvedType(i);
     }
 
     auto declKindForType = [](Type type) -> DescriptiveDeclKind {

lib/Sema/TypeCheckProtocol.cpp

@@ -5592,13 +5592,9 @@ void swift::diagnoseConformanceFailure(Type T,
       if (!classDecl)
         return;
 
-      auto inheritedClause = classDecl->getInherited().getEntries();
-      for (unsigned i : indices(inheritedClause)) {
-        auto &inherited = inheritedClause[i];
-
-        // Find the inherited type.
-        InheritedTypeRequest request{classDecl, i, TypeResolutionStage::Interface};
-        Type inheritedTy = evaluateOrDefault(ctx.evaluator, request, Type());
+      auto inheritedTypes = classDecl->getInherited();
+      for (auto i : inheritedTypes.getIndices()) {
+        Type inheritedTy = inheritedTypes.getResolvedType(i);
 
         // If it's a class, we cannot suggest a different class to inherit
         // from.
@@ -5608,7 +5604,8 @@ void swift::diagnoseConformanceFailure(Type T,
         // Is it the NSObject protocol?
         if (auto protoTy = inheritedTy->getAs<ProtocolType>()) {
           if (isNSObjectProtocol(protoTy->getDecl())) {
-            diag.fixItReplace(inherited.getSourceRange(), "NSObject");
+            diag.fixItReplace(inheritedTypes.getEntry(i).getSourceRange(),
+                              "NSObject");
             return;
           }
         }