[clang][ASTImporter][StructuralEquivalence] improve StructuralEquivalence on recordType

[jcsxky]

Types comparison in StructuralEquivalence ignores its DeclContext when they are generated by template specialization implicitly and this will produce incorrect result. Add comparison of DeclContext of ClassTemplateSpecializationDecl to improve result.
fix issue

[llvmbot]

@llvm/pr-subscribers-clang

Author: Qizhi Hu (jcsxky)

Changes

Types comparison in StructuralEquivalence ignores its DeclContext when they are generated by template specialization implicitly and this will produce incorrect result. Add comparison of DeclContext of ClassTemplateSpecializationDecl to improve result.

---

Full diff: https://github.com/llvm/llvm-project/pull/76226.diff

2 Files Affected:

• (modified) clang/lib/AST/ASTStructuralEquivalence.cpp (+12-3)
• (modified) clang/unittests/AST/StructuralEquivalenceTest.cpp (+22)

diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp
index 6bb4bf14b873d7..7c04c09bb80874 100644
--- a/clang/lib/AST/ASTStructuralEquivalence.cpp
+++ b/clang/lib/AST/ASTStructuralEquivalence.cpp
@@ -1107,11 +1107,20 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
   }
 
   case Type::Record:
-  case Type::Enum:
-    if (!IsStructurallyEquivalent(Context, cast<TagType>(T1)->getDecl(),
-                                  cast<TagType>(T2)->getDecl()))
+  case Type::Enum: {
+    auto *D1 = cast<TagType>(T1)->getDecl();
+    auto *D2 = cast<TagType>(T2)->getDecl();
+    if (!IsStructurallyEquivalent(Context, D1, D2))
+      return false;
+    auto *D1Spec =
+        dyn_cast_or_null<ClassTemplateSpecializationDecl>(D1->getDeclContext());
+    auto *D2Spec =
+        dyn_cast_or_null<ClassTemplateSpecializationDecl>(D2->getDeclContext());
+    if (nullptr != D1Spec && nullptr != D2Spec &&
+        !IsStructurallyEquivalent(Context, D1Spec, D2Spec))
       return false;
     break;
+  }
 
   case Type::TemplateTypeParm: {
     const auto *Parm1 = cast<TemplateTypeParmType>(T1);
diff --git a/clang/unittests/AST/StructuralEquivalenceTest.cpp b/clang/unittests/AST/StructuralEquivalenceTest.cpp
index 44d950cfe758f1..b54d149152e105 100644
--- a/clang/unittests/AST/StructuralEquivalenceTest.cpp
+++ b/clang/unittests/AST/StructuralEquivalenceTest.cpp
@@ -1024,6 +1024,28 @@ TEST_F(StructuralEquivalenceRecordContextTest, TransparentContextInNamespace) {
   EXPECT_TRUE(testStructuralMatch(Decls));
 }
 
+TEST_F(StructuralEquivalenceRecordContextTest, RecordWithinTemplateClass) {
+  std::string Code =
+      R"(
+      template <typename T> struct O {
+        struct M {};
+      };
+      )";
+  auto t = makeDecls<VarDecl>(Code + R"(
+      typedef O<int>::M MT1;
+      MT1 A;
+      )",
+                              Code + R"(
+      namespace {
+        struct I {};
+      } // namespace
+      typedef O<I>::M MT2;
+      MT2 A;
+      )",
+                              Lang_CXX11, varDecl(hasName("A")));
+  EXPECT_FALSE(testStructuralMatch(t));
+}
+
 TEST_F(StructuralEquivalenceTest, NamespaceOfRecordMember) {
   auto Decls = makeNamedDecls(
       R"(

[balazske]

It would be better to check if D2Spec is null.

[jcsxky]

Done.

[balazske]

I see now that the old code was better, there is a previous check DC1->getDeclKind() != DC2->getDeclKind(), this should ensure that the type is the same.

[jcsxky]

revert