[ASTImporter] Fix redecl failures of Class and ClassTemplate

Summary:
Redecl chains of classes and class templates are not handled well
currently. We want to handle them similarly to functions, i.e. try to
keep the structure of the original AST as much as possible. The aim is
to not squash a prototype with a definition, rather we create both and
put them in a redecl chain.

Reviewers: a_sidorin, shafik, a.sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58502

llvm-svn: 355390

2 files changed, 6 insertions, 40 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index e2cfe9a347e..3b484f94003 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2553,26 +2553,6 @@ ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
             Decl::FOK_None;
   }
 
-  // If this record has a definition in the translation unit we're coming from,
-  // but this particular declaration is not that definition, import the
-  // definition and map to that.
-  TagDecl *Definition = D->getDefinition();
-  if (Definition && Definition != D &&
-      // Friend template declaration must be imported on its own.
-      !IsFriendTemplate &&
-      // In contrast to a normal CXXRecordDecl, the implicit
-      // CXXRecordDecl of ClassTemplateSpecializationDecl is its redeclaration.
-      // The definition of the implicit CXXRecordDecl in this case is the
-      // ClassTemplateSpecializationDecl itself. Thus, we start with an extra
-      // condition in order to be able to import the implict Decl.
-      !D->isImplicit()) {
-    ExpectedDecl ImportedDefOrErr = import(Definition);
-    if (!ImportedDefOrErr)
-      return ImportedDefOrErr.takeError();
-
-    return Importer.MapImported(D, *ImportedDefOrErr);
-  }
-
   // Import the major distinguishing characteristics of this record.
   DeclContext *DC, *LexicalDC;
   DeclarationName Name;
@@ -2601,7 +2581,8 @@ ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
     auto FoundDecls =
         Importer.findDeclsInToCtx(DC, SearchName);
     if (!FoundDecls.empty()) {
-      // We're going to have to compare D against potentially conflicting Decls, so complete it.
+      // We're going to have to compare D against potentially conflicting Decls,
+      // so complete it.
       if (D->hasExternalLexicalStorage() && !D->isCompleteDefinition())
         D->getASTContext().getExternalSource()->CompleteType(D);
     }
@@ -4976,17 +4957,6 @@ static ClassTemplateDecl *getDefinition(ClassTemplateDecl *D) {
 ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
   bool IsFriend = D->getFriendObjectKind() != Decl::FOK_None;
 
-  // If this template has a definition in the translation unit we're coming
-  // from, but this particular declaration is not that definition, import the
-  // definition and map to that.
-  ClassTemplateDecl *Definition = getDefinition(D);
-  if (Definition && Definition != D && !IsFriend) {
-    if (ExpectedDecl ImportedDefOrErr = import(Definition))
-      return Importer.MapImported(D, *ImportedDefOrErr);
-    else
-      return ImportedDefOrErr.takeError();
-  }
-
   // Import the major distinguishing characteristics of this class template.
   DeclContext *DC, *LexicalDC;
   DeclarationName Name;
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 6bfb7ad065e..08d57e2e433 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -4241,8 +4241,7 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportDefinitionAfterImportedPrototype)
-// FIXME This does not pass, possible error with Class import.
-ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, DISABLED_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportDefinitionAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportDefinitionAfterImportedPrototype)
@@ -4250,16 +4249,14 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,
                                         ImportDefinitionAfterImportedPrototype)
-// FIXME This does not pass, possible error with ClassTemplate import.
-ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, DISABLED_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportDefinitionAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportDefinitionAfterImportedPrototype)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportPrototypeAfterImportedDefinition)
-// FIXME This does not pass, possible error with Class import.
-ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, DISABLED_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportPrototypeAfterImportedDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypeAfterImportedDefinition)
@@ -4267,8 +4264,7 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,
                                         ImportPrototypeAfterImportedDefinition)
-// FIXME This does not pass, possible error with ClassTemplate import.
-ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, DISABLED_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportPrototypeAfterImportedDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportPrototypeAfterImportedDefinition)