Remove hasReturnTypeDeclaredInside

Now FunctionReturnTypeCycleDetector works out with nested
 typenames as well.

Author: ganenkokb-yandex

clang/lib/AST/ASTImporter.cpp

@@ -744,13 +744,8 @@ namespace clang {
     Error ImportOverriddenMethods(CXXMethodDecl *ToMethod,
                                   CXXMethodDecl *FromMethod);
 
-    Expected<FunctionDecl *> FindFunctionTemplateSpecialization(
-        FunctionDecl *FromFD);
-
-    // Returns true if the given function has a placeholder return type and
-    // that type is declared inside the body of the function.
-    // E.g. auto f() { struct X{}; return X(); }
-    bool hasReturnTypeDeclaredInside(FunctionDecl *D);
+    Expected<FunctionDecl *>
+    FindFunctionTemplateSpecialization(FunctionDecl *FromFD);
   };
 
 template <typename InContainerTy>
@@ -3902,30 +3897,6 @@ class IsTypeDeclaredInsideVisitor
 };
 } // namespace
 
-/// This function checks if the given function has a return type that contains
-/// a reference (in any way) to a declaration inside the same function.
-bool ASTNodeImporter::hasReturnTypeDeclaredInside(FunctionDecl *D) {
-  QualType FromTy = D->getType();
-  const auto *FromFPT = FromTy->getAs<FunctionProtoType>();
-  assert(FromFPT && "Must be called on FunctionProtoType");
-
-  auto IsCXX11Lambda = [&]() {
-    if (Importer.FromContext.getLangOpts().CPlusPlus14) // C++14 or later
-      return false;
-
-    return isLambdaMethod(D);
-  };
-
-  QualType RetT = FromFPT->getReturnType();
-  if (isa<AutoType>(RetT.getTypePtr()) || IsCXX11Lambda()) {
-    FunctionDecl *Def = D->getDefinition();
-    IsTypeDeclaredInsideVisitor Visitor(Def ? Def : D);
-    return Visitor.CheckType(RetT);
-  }
-
-  return false;
-}
-
 ExplicitSpecifier
 ASTNodeImporter::importExplicitSpecifier(Error &Err, ExplicitSpecifier ESpec) {
   Expr *ExplicitExpr = ESpec.getExpr();
@@ -4074,9 +4045,8 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
     // To avoid an infinite recursion when importing, create the FunctionDecl
     // with a simplified return type.
     // Reuse this approach for auto return types declared as typenames from
-    // template pamams, tracked in FunctionReturnTypeCycleDetector.
-    if (hasReturnTypeDeclaredInside(D) ||
-        Importer.FunctionReturnTypeCycleDetector->isCycle(D)) {
+    // template params, tracked in FunctionReturnTypeCycleDetector.
+    if (Importer.FunctionReturnTypeCycleDetector->isCycle(D)) {
       FromReturnTy = Importer.getFromContext().VoidTy;
       UsedDifferentProtoType = true;
     }