[clang][ASTImporter][StructuralEquivalence] improve StructuralEquivalence on recordType (llvm#76226)

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](llvm#65913)

Co-authored-by: huqizhi <[email protected]>

Author: jcsxky

clang/lib/AST/ASTStructuralEquivalence.cpp

@@ -1463,8 +1463,9 @@ IsStructurallyEquivalentLambdas(StructuralEquivalenceContext &Context,
 }
 
 /// Determine if context of a class is equivalent.
-static bool IsRecordContextStructurallyEquivalent(RecordDecl *D1,
-                                                  RecordDecl *D2) {
+static bool
+IsRecordContextStructurallyEquivalent(StructuralEquivalenceContext &Context,
+                                      RecordDecl *D1, RecordDecl *D2) {
   // The context should be completely equal, including anonymous and inline
   // namespaces.
   // We compare objects as part of full translation units, not subtrees of
@@ -1491,6 +1492,12 @@ static bool IsRecordContextStructurallyEquivalent(RecordDecl *D1,
         return false;
     }
 
+    if (auto *D1Spec = dyn_cast<ClassTemplateSpecializationDecl>(DC1)) {
+      auto *D2Spec = dyn_cast<ClassTemplateSpecializationDecl>(DC2);
+      if (!IsStructurallyEquivalent(Context, D1Spec, D2Spec))
+        return false;
+    }
+
     DC1 = DC1->getParent()->getNonTransparentContext();
     DC2 = DC2->getParent()->getNonTransparentContext();
   }
@@ -1544,7 +1551,7 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
   // If the records occur in different context (namespace), these should be
   // different. This is specially important if the definition of one or both
   // records is missing.
-  if (!IsRecordContextStructurallyEquivalent(D1, D2))
+  if (!IsRecordContextStructurallyEquivalent(Context, D1, D2))
     return false;
 
   // If both declarations are class template specializations, we know

clang/unittests/AST/StructuralEquivalenceTest.cpp

@@ -1024,6 +1024,29 @@ TEST_F(StructuralEquivalenceRecordContextTest, TransparentContextInNamespace) {
   EXPECT_TRUE(testStructuralMatch(Decls));
 }
 
+TEST_F(StructuralEquivalenceRecordContextTest,
+       ClassTemplateSpecializationContext) {
+  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"(