[ASTImporter] Fix redecl failures of FunctionTemplateSpec

Summary:
Redecl chains of function 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.

Reviewers: a_sidorin, shafik, a.sidorin

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58668

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@356455 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 60 insertions, 77 deletions

diff --git a/unittests/AST/ASTImporterTest.cpp b/unittests/AST/ASTImporterTest.cpp
index 497d22007e..d6bd134985 100644
--- a/unittests/AST/ASTImporterTest.cpp
+++ b/unittests/AST/ASTImporterTest.cpp
@@ -3978,6 +3978,45 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
   std::string getDefinition() { return TypeParam::Definition; }
   BindableMatcher<Decl> getPattern() const { return TypeParam().getPattern(); }
 
+  void CheckPreviousDecl(Decl *Prev, Decl *Current) {
+    ASSERT_NE(Prev, Current);
+    ASSERT_EQ(&Prev->getASTContext(), &Current->getASTContext());
+    EXPECT_EQ(Prev->getCanonicalDecl(), Current->getCanonicalDecl());
+
+    // Templates.
+    if (auto *PrevT = dyn_cast<TemplateDecl>(Prev)) {
+      EXPECT_EQ(Current->getPreviousDecl(), Prev);
+      auto *CurrentT = cast<TemplateDecl>(Current);
+      ASSERT_TRUE(PrevT->getTemplatedDecl());
+      ASSERT_TRUE(CurrentT->getTemplatedDecl());
+      EXPECT_EQ(CurrentT->getTemplatedDecl()->getPreviousDecl(),
+                PrevT->getTemplatedDecl());
+      return;
+    }
+
+    // Specializations.
+    if (auto *PrevF = dyn_cast<FunctionDecl>(Prev)) {
+      if (PrevF->getTemplatedKind() ==
+          FunctionDecl::TK_FunctionTemplateSpecialization) {
+        // There may be a hidden fwd spec decl before a spec decl.
+        // In that case the previous visible decl can be reached through that
+        // invisible one.
+        EXPECT_THAT(Prev, testing::AnyOf(
+                              Current->getPreviousDecl(),
+                              Current->getPreviousDecl()->getPreviousDecl()));
+        auto *ToTU = Prev->getTranslationUnitDecl();
+        auto *TemplateD = FirstDeclMatcher<FunctionTemplateDecl>().match(
+            ToTU, functionTemplateDecl());
+        auto *FirstSpecD = *(TemplateD->spec_begin());
+        EXPECT_EQ(FirstSpecD->getCanonicalDecl(), PrevF->getCanonicalDecl());
+        return;
+      }
+    }
+
+    // The rest: Classes, Functions, etc.
+    EXPECT_EQ(Current->getPreviousDecl(), Prev);
+  }
+
   void
   TypedTest_PrototypeShouldBeImportedAsAPrototypeWhenThereIsNoDefinition() {
     Decl *FromTU = getTuDecl(getPrototype(), Lang_CXX);
@@ -4030,14 +4069,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(Imported1 == To1);
     EXPECT_FALSE(To0->isThisDeclarationADefinition());
     EXPECT_FALSE(To1->isThisDeclarationADefinition());
-    EXPECT_EQ(To1->getPreviousDecl(), To0);
-    if (auto *ToT0 = dyn_cast<TemplateDecl>(To0)) {
-      auto *ToT1 = cast<TemplateDecl>(To1);
-      ASSERT_TRUE(ToT0->getTemplatedDecl());
-      ASSERT_TRUE(ToT1->getTemplatedDecl());
-      EXPECT_EQ(ToT1->getTemplatedDecl()->getPreviousDecl(),
-                ToT0->getTemplatedDecl());
-    }
+
+    CheckPreviousDecl(To0, To1);
   }
 
   void TypedTest_ImportDefinitionAfterImportedPrototype() {
@@ -4059,14 +4092,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(ImportedDef == ToDef);
     EXPECT_FALSE(ToProto->isThisDeclarationADefinition());
     EXPECT_TRUE(ToDef->isThisDeclarationADefinition());
-    EXPECT_EQ(ToDef->getPreviousDecl(), ToProto);
-    if (auto *ToProtoT = dyn_cast<TemplateDecl>(ToProto)) {
-      auto *ToDefT = cast<TemplateDecl>(ToDef);
-      ASSERT_TRUE(ToProtoT->getTemplatedDecl());
-      ASSERT_TRUE(ToDefT->getTemplatedDecl());
-      EXPECT_EQ(ToDefT->getTemplatedDecl()->getPreviousDecl(),
-                ToProtoT->getTemplatedDecl());
-    }
+
+    CheckPreviousDecl(ToProto, ToDef);
   }
 
   void TypedTest_ImportPrototypeAfterImportedDefinition() {
@@ -4088,14 +4115,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(ImportedProto == ToProto);
     EXPECT_TRUE(ToDef->isThisDeclarationADefinition());
     EXPECT_FALSE(ToProto->isThisDeclarationADefinition());
-    EXPECT_EQ(ToProto->getPreviousDecl(), ToDef);
-    if (auto *ToDefT = dyn_cast<TemplateDecl>(ToDef)) {
-      auto *ToProtoT = cast<TemplateDecl>(ToProto);
-      ASSERT_TRUE(ToDefT->getTemplatedDecl());
-      ASSERT_TRUE(ToProtoT->getTemplatedDecl());
-      EXPECT_EQ(ToProtoT->getTemplatedDecl()->getPreviousDecl(),
-                ToDefT->getTemplatedDecl());
-    }
+
+    CheckPreviousDecl(ToDef, ToProto);
   }
 
   void TypedTest_ImportPrototypes() {
@@ -4117,27 +4138,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(Imported1 == To1);
     EXPECT_FALSE(To0->isThisDeclarationADefinition());
     EXPECT_FALSE(To1->isThisDeclarationADefinition());
-    EXPECT_EQ(To1->getPreviousDecl(), To0);
-    if (auto *ToT0 = dyn_cast<TemplateDecl>(To0)) {
-      auto *ToT1 = cast<TemplateDecl>(To1);
-      ASSERT_TRUE(ToT0->getTemplatedDecl());
-      ASSERT_TRUE(ToT1->getTemplatedDecl());
-      EXPECT_EQ(ToT1->getTemplatedDecl()->getPreviousDecl(),
-                ToT0->getTemplatedDecl());
-    }
-    // Extra check for specializations.
-    // FIXME Add this check to other tests too (possibly factor out into a
-    // function), when they start to pass.
-    if (auto *From0F = dyn_cast<FunctionDecl>(From0)) {
-      auto *To0F = cast<FunctionDecl>(To0);
-      if (From0F->getTemplatedKind() ==
-          FunctionDecl::TK_FunctionTemplateSpecialization) {
-        auto *TemplateD = FirstDeclMatcher<FunctionTemplateDecl>().match(
-            ToTU, functionTemplateDecl());
-        auto *FirstSpecD = *(TemplateD->spec_begin());
-        EXPECT_EQ(FirstSpecD->getCanonicalDecl(), To0F->getCanonicalDecl());
-      }
-    }
+
+    CheckPreviousDecl(To0, To1);
   }
 
   void TypedTest_ImportDefinitions() {
@@ -4182,14 +4184,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(ImportedProto == ToProto);
     EXPECT_TRUE(ToDef->isThisDeclarationADefinition());
     EXPECT_FALSE(ToProto->isThisDeclarationADefinition());
-    EXPECT_EQ(ToProto->getPreviousDecl(), ToDef);
-    if (auto *ToDefT = dyn_cast<TemplateDecl>(ToDef)) {
-      auto *ToProtoT = cast<TemplateDecl>(ToProto);
-      ASSERT_TRUE(ToDefT->getTemplatedDecl());
-      ASSERT_TRUE(ToProtoT->getTemplatedDecl());
-      EXPECT_EQ(ToProtoT->getTemplatedDecl()->getPreviousDecl(),
-                ToDefT->getTemplatedDecl());
-    }
+
+    CheckPreviousDecl(ToDef, ToProto);
   }
 
   void TypedTest_ImportPrototypeThenDefinition() {
@@ -4213,14 +4209,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(ImportedProto == ToProto);
     EXPECT_TRUE(ToDef->isThisDeclarationADefinition());
     EXPECT_FALSE(ToProto->isThisDeclarationADefinition());
-    EXPECT_EQ(ToDef->getPreviousDecl(), ToProto);
-    if (auto *ToDefT = dyn_cast<TemplateDecl>(ToDef)) {
-      auto *ToProtoT = cast<TemplateDecl>(ToProto);
-      ASSERT_TRUE(ToDefT->getTemplatedDecl());
-      ASSERT_TRUE(ToProtoT->getTemplatedDecl());
-      EXPECT_EQ(ToDefT->getTemplatedDecl()->getPreviousDecl(),
-                ToProtoT->getTemplatedDecl());
-    }
+
+    CheckPreviousDecl(ToProto, ToDef);
   }
 
   void TypedTest_WholeRedeclChainIsImportedAtOnce() {
@@ -4262,7 +4252,8 @@ struct RedeclChain : ASTImporterOptionSpecificTestBase {
     EXPECT_TRUE(DefinitionD->getPreviousDecl());
     EXPECT_FALSE(
         DefinitionD->getPreviousDecl()->isThisDeclarationADefinition());
-    EXPECT_EQ(DefinitionD->getPreviousDecl()->getPreviousDecl(), ProtoD);
+
+    CheckPreviousDecl(ProtoD, DefinitionD->getPreviousDecl());
   }
 };
 
@@ -4366,11 +4357,10 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate, ,
                                         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, FunctionTemplateSpec, ,
+                                        ImportPrototypes)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportDefinitions)
@@ -4382,11 +4372,10 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate, ,
                                         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, FunctionTemplateSpec, ,
+                                        ImportDefinitions)
 
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Function, ,
                                         ImportDefinitionThenPrototype)
@@ -4398,9 +4387,7 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate, ,
                                         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_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportDefinitionThenPrototype)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
                                         ImportDefinitionThenPrototype)
@@ -4415,9 +4402,7 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate, ,
                                         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_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportPrototypeThenDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, ClassTemplateSpec, ,
                                         ImportPrototypeThenDefinition)
@@ -4437,9 +4422,7 @@ ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, Variable, ,
                                         ImportPrototypeThenProtoAndDefinition)
 ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplate, ,
                                         ImportPrototypeThenProtoAndDefinition)
-// FIXME This does not pass, possible error with Spec import.
-ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec,
-                                        DISABLED_,
+ASTIMPORTER_INSTANTIATE_TYPED_TEST_CASE(RedeclChain, FunctionTemplateSpec, ,
                                         ImportPrototypeThenProtoAndDefinition)
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, RedeclChainFunction,