[ASTImporter] Fix redecl failures of ClassTemplateSpec

[martong]

Summary

Redecl chains of class template specializations 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.

[a_sidorin]

Hi Gabor,
Thanks for the patch! It looks good to me except some stylish nits.

lib/AST/ASTImporter.cpp

5130

Could you please also replace "those those" to "those" in the comment below?

5144

The comment is a bit broken.

[martong]

• Fix some comments

[martong]

Alexei, thanks for the review!

[shafik]

lib/AST/ASTImporter.cpp

5147

ODR violations are ill-formed no diagnostic required. So currently will this fail for cases that clang proper would not?

[martong]

lib/AST/ASTImporter.cpp

5147

ODR violations are ill-formed no diagnostic required.

ASTStructuralEquivalenceContext already provides diagnostic in the ODR cases. E.g.:

// Check for equivalent field names.
IdentifierInfo *Name1 = Field1->getIdentifier();
IdentifierInfo *Name2 = Field2->getIdentifier();
if (!::IsStructurallyEquivalent(Name1, Name2)) {
  if (Context.Complain) {
    Context.Diag2(Owner2->getLocation(),
                  Context.ErrorOnTagTypeMismatch
                      ? diag::err_odr_tag_type_inconsistent
                      : diag::warn_odr_tag_type_inconsistent)
        << Context.ToCtx.getTypeDeclType(Owner2);
    Context.Diag2(Field2->getLocation(), diag::note_odr_field_name)
        << Field2->getDeclName();
    Context.Diag1(Field1->getLocation(), diag::note_odr_field_name)
        << Field1->getDeclName();
  }
  return false;
}

We change this to be always a Warning instead of an Error in this patch: https://reviews.llvm.org/D58897

So currently will this fail for cases that clang proper would not?

Well, I think the situation is more subtle than that.
There are cases when we can link two translation units and the linker provides a valid executable even if there is an ODR violation of a type. There is no type information used during linkage, except for functions' mangled names and visibility. That ODR violation is recognized though when we do the merge in the AST level (and I think it is useful to diagnose them).
So if "clang proper" includes the linker then the answer is yes. If not then we are talking about only one translation unit and the answer is no.

[martong]

@shafik Ping

[shafik]

LGTM

lib/AST/ASTImporter.cpp

if (FromTemplated->isCompleteDefinition() &&
     // FIXME: Import definition!
   }
 
   return D2;
 }
 
 ExpectedDecl ASTNodeImporter::VisitClassTemplateSpecializationDecl(
                                           ClassTemplateSpecializationDecl *D) {
-  // 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) {
-    if (ExpectedDecl ImportedDefOrErr = import(Definition))
-      return Importer.MapImported(D, *ImportedDefOrErr);
-    else
-      return ImportedDefOrErr.takeError();
-  }
-
   ClassTemplateDecl *ClassTemplate;
   if (Error Err = importInto(ClassTemplate, D->getSpecializedTemplate()))
     return std::move(Err);
 
   // Import the context of this declaration.
   DeclContext *DC, *LexicalDC;
   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
     return std::move(Err);
 
   // Import template arguments.
   SmallVector<TemplateArgument, 2> TemplateArgs;
   if (Error Err = ImportTemplateArguments(
       D->getTemplateArgs().data(), D->getTemplateArgs().size(), TemplateArgs))
     return std::move(Err);
 
   // Try to find an existing specialization with these template arguments.
   void *InsertPos = nullptr;
-  ClassTemplateSpecializationDecl *D2 = nullptr;
+  ClassTemplateSpecializationDecl *PrevDecl = nullptr;
   ClassTemplatePartialSpecializationDecl *PartialSpec =
             dyn_cast<ClassTemplatePartialSpecializationDecl>(D);
   if (PartialSpec)
-    D2 = ClassTemplate->findPartialSpecialization(TemplateArgs, InsertPos);
+    PrevDecl =
+        ClassTemplate->findPartialSpecialization(TemplateArgs, InsertPos);
   else
-    D2 = ClassTemplate->findSpecialization(TemplateArgs, InsertPos);
-  ClassTemplateSpecializationDecl * const PrevDecl = D2;
-  RecordDecl *FoundDef = D2 ? D2->getDefinition() : nullptr;
-  if (FoundDef) {
-    if (!D->isCompleteDefinition()) {
-      // The "From" translation unit only had a forward declaration; call it
-      // the same declaration.
-      // TODO Handle the redecl chain properly!
-      return Importer.MapImported(D, FoundDef);
-    }
-
-    if (IsStructuralMatch(D, FoundDef)) {
+    PrevDecl = ClassTemplate->findSpecialization(TemplateArgs, InsertPos);
 
-      Importer.MapImported(D, FoundDef);
-
-      // Import those those default field initializers which have been
+  if (PrevDecl) {
+    if (IsStructuralMatch(D, PrevDecl)) {
+      if (D->isThisDeclarationADefinition() && PrevDecl->getDefinition()) {
+        Importer.MapImported(D, PrevDecl->getDefinition());
+        // Import those default field initializers which have been
         // instantiated in the "From" context, but not in the "To" context.
-      for (auto *FromField : D->fields()) {
-        auto ToOrErr = import(FromField);
-        if (!ToOrErr)
-          // FIXME: return the error?
-          consumeError(ToOrErr.takeError());
-      }
+        for (auto *FromField : D->fields())
+          Importer.Import(FromField);
 
         // Import those methods which have been instantiated in the
         // "From" context, but not in the "To" context.
-      for (CXXMethodDecl *FromM : D->methods()) {
-        auto ToOrErr = import(FromM);
-        if (!ToOrErr)
-          // FIXME: return the error?
-          consumeError(ToOrErr.takeError());
-      }
+        for (CXXMethodDecl *FromM : D->methods())
+          Importer.Import(FromM);
 
         // TODO Import instantiated default arguments.
         // TODO Import instantiated exception specifications.
         //
-      // Generally, ASTCommon.h/DeclUpdateKind enum gives a very good hint what
-      // else could be fused during an AST merge.
-
-      return FoundDef;
-    }
-  } else { // We either couldn't find any previous specialization in the "To"
-           // context,  or we found one but without definition.  Let's create a
-           // new specialization and register that at the class template.
+        // Generally, ASTCommon.h/DeclUpdateKind enum gives a very good hint
+        // what else could be fused during an AST merge.
+        return PrevDecl;
+      }
+    } else { // ODR violation.
+      // FIXME HandleNameConflict
+      return nullptr;
+    }
 
-    // Import the location of this declaration.
-    ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
-    if (!BeginLocOrErr)
-      return BeginLocOrErr.takeError();
-    ExpectedSLoc IdLocOrErr = import(D->getLocation());
-    if (!IdLocOrErr)
-      return IdLocOrErr.takeError();
 
-    if (PartialSpec) {
-      // Import TemplateArgumentListInfo.
-      TemplateArgumentListInfo ToTAInfo;
-      const auto &ASTTemplateArgs = *PartialSpec->getTemplateArgsAsWritten();
-      if (Error Err = ImportTemplateArgumentListInfo(ASTTemplateArgs, ToTAInfo))
-        return std::move(Err);
+  // Create the specialization.
+  ClassTemplateSpecializationDecl *D2 = nullptr;
 
-      QualType CanonInjType;
-      if (Error Err = importInto(
-          CanonInjType, PartialSpec->getInjectedSpecializationType()))
-        return std::move(Err);
-      CanonInjType = CanonInjType.getCanonicalType();
 
-      auto ToTPListOrErr = ImportTemplateParameterList(
-          PartialSpec->getTemplateParameters());
-      if (!ToTPListOrErr)
-        return ToTPListOrErr.takeError();
 
-      if (GetImportedOrCreateDecl<ClassTemplatePartialSpecializationDecl>(
-              D2, D, Importer.getToContext(), D->getTagKind(), DC,
-              *BeginLocOrErr, *IdLocOrErr, *ToTPListOrErr, ClassTemplate,
-              llvm::makeArrayRef(TemplateArgs.data(), TemplateArgs.size()),
-              ToTAInfo, CanonInjType,
-              cast_or_null<ClassTemplatePartialSpecializationDecl>(PrevDecl)))
-        return D2;
 
-      // Update InsertPos, because preceding import calls may have invalidated
-      // it by adding new specializations.
-      if (!ClassTemplate->findPartialSpecialization(TemplateArgs, InsertPos))
-        // Add this partial specialization to the class template.
-        ClassTemplate->AddPartialSpecialization(
-            cast<ClassTemplatePartialSpecializationDecl>(D2), InsertPos);
 
-    } else { // Not a partial specialization.
-      if (GetImportedOrCreateDecl(
-              D2, D, Importer.getToContext(), D->getTagKind(), DC,
-              *BeginLocOrErr, *IdLocOrErr, ClassTemplate, TemplateArgs,
-              PrevDecl))
-        return D2;
 
-      // Update InsertPos, because preceding import calls may have invalidated
-      // it by adding new specializations.
-      if (!ClassTemplate->findSpecialization(TemplateArgs, InsertPos))
-        // Add this specialization to the class template.
-        ClassTemplate->AddSpecialization(D2, InsertPos);
-    }
 
-    D2->setSpecializationKind(D->getSpecializationKind());
 
-    // Import the qualifier, if any.
-    if (auto LocOrErr = import(D->getQualifierLoc()))
-      D2->setQualifierInfo(*LocOrErr);
-    else
-      return LocOrErr.takeError();
+  // Set the context of this specialization/instantiation.
+  D2->setLexicalDeclContext(LexicalDC);
+
+  // Add to the DC only if it was an explicit specialization/instantiation.
+  if (D2->isExplicitInstantiationOrSpecialization()) {
+    LexicalDC->addDeclInternal(D2);
+  }
+
 
-    if (auto *TSI = D->getTypeAsWritten()) {
-      if (auto TInfoOrErr = import(TSI))
-        D2->setTypeAsWritten(*TInfoOrErr);
-      else
-        return TInfoOrErr.takeError();
 
-      if (auto LocOrErr = import(D->getTemplateKeywordLoc()))
-        D2->setTemplateKeywordLoc(*LocOrErr);
-      else
-        return LocOrErr.takeError();
 
-      if (auto LocOrErr = import(D->getExternLoc()))
-        D2->setExternLoc(*LocOrErr);
-      else
-        return LocOrErr.takeError();
-    }
 
-    if (D->getPointOfInstantiation().isValid()) {
-      if (auto POIOrErr = import(D->getPointOfInstantiation()))
-        D2->setPointOfInstantiation(*POIOrErr);
-      else
-        return POIOrErr.takeError();
-    }
 
-    D2->setTemplateSpecializationKind(D->getTemplateSpecializationKind());
 
-    // Set the context of this specialization/instantiation.
-    D2->setLexicalDeclContext(LexicalDC);
-
-    // Add to the DC only if it was an explicit specialization/instantiation.
-    if (D2->isExplicitInstantiationOrSpecialization()) {
-      LexicalDC->addDeclInternal(D2);
-    }
-  }
   if (D->isCompleteDefinition())
     if (Error Err = ImportDefinition(D, D2))
       return std::move(Err);
 
   return D2;
 }
 
 ExpectedDecl ASTNodeImporter::VisitVarTemplateDecl(VarTemplateDecl *D) {
Decl *ASTImporter::Import(Decl *FromD) {
   // Import the type.
   ExpectedDecl ToDOrErr = Importer.Visit(FromD);
   if (!ToDOrErr) {
     llvm::consumeError(ToDOrErr.takeError());
     return nullptr;
   }
   ToD = *ToDOrErr;
 
+  // FIXME Use getImportDeclErrorIfAny() here (and return with the error) once
+  // the error handling is finished in GetImportedOrCreateSpecialDecl().
+  if (!ToD) {
+    return nullptr;
+  }
+
   // Once the decl is connected to the existing declarations, i.e. when the
   // redecl chain is properly set then we populate the lookup again.
   // This way the primary context will be able to find all decls.
   AddToLookupTable(ToD);
 
   // Notify subclasses.
   Imported(FromD, ToD);
 

unittests/AST/ASTImporterTest.cpp

TEST_P(ASTImporterOptionSpecificTestBase,
   auto *ImportedSpec = Import(FromSpec, Lang_CXX11);
 
   // We expect one (ODR) warning during the import.
   EXPECT_EQ(1u, ToTU->getASTContext().getDiagnostics().getNumWarnings());
 
   // The second specialization is different from the first, thus it violates
   // ODR, consequently we expect to keep the first specialization only, which is
   // already in the "To" context.
-  EXPECT_TRUE(ImportedSpec);
-  auto *ToSpec = FirstDeclMatcher<ClassTemplateSpecializationDecl>().match(
-      ToTU, classTemplateSpecializationDecl(hasName("X")));
-  EXPECT_EQ(ImportedSpec, ToSpec);
-  EXPECT_EQ(1u, DeclCounter<ClassTemplateSpecializationDecl>().match(
-                    ToTU, classTemplateSpecializationDecl()));
+  EXPECT_FALSE(ImportedSpec);
+  EXPECT_EQ(1u,
+            DeclCounter<ClassTemplateSpecializationDecl>().match(
+                ToTU, classTemplateSpecializationDecl(hasName("X"))));
 }
 
 TEST_P(ASTImporterOptionSpecificTestBase,
        MergeCtorOfClassTemplateSpecialization) {
   std::string ClassTemplate =
       R"(
       template <typename T>
       struct X {
static constexpr auto *Definition =
       template <>
       void X<int>() {}
       )";
   BindableMatcher<Decl> getPattern() {
     return functionDecl(hasName("X"), isExplicitTemplateSpecialization());
   }
 };
 
+struct ClassTemplateSpec {
+  using DeclTy = ClassTemplateSpecializationDecl;
+  static constexpr auto *Prototype =
+    R"(
+    template <class T> class X;
+    template <> class X<int>;
+    )";
+  static constexpr auto *Definition =
+    R"(
+    template <class T> class X;
+    template <> class X<int> {};
+    )";
+  BindableMatcher<Decl> getPattern() {
+    return classTemplateSpecializationDecl(hasName("X"), unless(isImplicit()));
+  }
+};
+
 template <typename TypeParam>
 struct RedeclChain : ASTImporterOptionSpecificTestBase {
 
   using DeclTy = typename TypeParam::DeclTy;
   std::string getPrototype() { return TypeParam::Prototype; }
   std::string getDefinition() { return TypeParam::Definition; }
   BindableMatcher<Decl> getPattern() const { return TypeParam().getPattern(); }
 
ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, FunctionTemplate, DISABLED_,
     PrototypeShouldBeImportedAsAPrototypeWhenThereIsNoDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, ClassTemplate, ,
     PrototypeShouldBeImportedAsAPrototypeWhenThereIsNoDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, FunctionTemplateSpec, ,
     PrototypeShouldBeImportedAsAPrototypeWhenThereIsNoDefinition)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
+    RedeclChain, ClassTemplateSpec, ,
+    PrototypeShouldBeImportedAsAPrototypeWhenThereIsNoDefinition)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, Function, , DefinitionShouldBeImportedAsADefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, Class, , DefinitionShouldBeImportedAsADefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, Variable, , DefinitionShouldBeImportedAsADefinition)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, FunctionTemplate, DISABLED_,
     DefinitionShouldBeImportedAsADefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, ClassTemplate, , DefinitionShouldBeImportedAsADefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
     RedeclChain, FunctionTemplateSpec, ,
     DefinitionShouldBeImportedAsADefinition)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(
+    RedeclChain, ClassTemplateSpec, , DefinitionShouldBeImportedAsADefinition)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportPrototypeAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportPrototypeAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypeAfterImportedPrototype)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,
                                         ImportPrototypeAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportPrototypeAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportPrototypeAfterImportedPrototype)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportPrototypeAfterImportedPrototype)
 
 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_,
                                         ImportDefinitionAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportDefinitionAfterImportedPrototype)
 // FIXME Enable this test, once we import function templates chains correctly.
 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_,
                                         ImportDefinitionAfterImportedPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportDefinitionAfterImportedPrototype)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        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_,
                                         ImportPrototypeAfterImportedDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypeAfterImportedDefinition)
 // FIXME Enable this test, once we import function templates chains correctly.
 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_,
                                         ImportPrototypeAfterImportedDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportPrototypeAfterImportedDefinition)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportPrototypeAfterImportedDefinition)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportPrototypes)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, , ImportPrototypes)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypes)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_, ImportPrototypes)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportPrototypes)
 // FIXME This does not pass, possible error with Spec import.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec,
                                         DISABLED_, ImportPrototypes)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportPrototypes)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportDefinitions)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportDefinitions)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportDefinitions)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_, ImportDefinitions)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportDefinitions)
 // FIXME This does not pass, possible error with Spec import.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec,
                                         DISABLED_, ImportDefinitions)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportDefinitions)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportDefinitionThenPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportDefinitionThenPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportDefinitionThenPrototype)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,
                                         ImportDefinitionThenPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportDefinitionThenPrototype)
 // FIXME This does not pass, possible error with Spec import.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec,
                                         DISABLED_,
                                         ImportDefinitionThenPrototype)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportDefinitionThenPrototype)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportPrototypeThenDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Class, ,
                                         ImportPrototypeThenDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypeThenDefinition)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,
                                         ImportPrototypeThenDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplate, ,
                                         ImportPrototypeThenDefinition)
 // FIXME This does not pass, possible error with Spec import.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec,
                                         DISABLED_,
                                         ImportPrototypeThenDefinition)
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
+                                        ImportPrototypeThenDefinition)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         WholeRedeclChainIsImportedAtOnce)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         WholeRedeclChainIsImportedAtOnce)
 // FIXME Enable this test, once we import function templates chains correctly.
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate,
                                         DISABLED_,

 INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainVariable,
                         DefaultTestValuesForRunOptions, );
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainFunctionTemplate,
                         DefaultTestValuesForRunOptions, );
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainClassTemplate,
                         DefaultTestValuesForRunOptions, );
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainFunctionTemplateSpec,
                         DefaultTestValuesForRunOptions, );
+INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainClassTemplateSpec,
+                        DefaultTestValuesForRunOptions, );
 
 
 
 struct ImportFriendClasses : ASTImporterOptionSpecificTestBase {};
 
 TEST_P(ImportFriendClasses, ImportOfFriendRecordDoesNotMergeDefinition) {
   Decl *FromTU = getTuDecl(
       R"(