[clang][ASTImporter] Fix partially import of repeated friend templates

Pointer comparison is not reliable in this case. Use ASTStructuralEquivalence
to compute FriendCountAndPosition.

Reviewed By: balazske

Differential Revision: https://reviews.llvm.org/D157684

Author: danix800

clang/lib/AST/ASTImporter.cpp

@@ -4079,22 +4079,34 @@ struct FriendCountAndPosition {
   unsigned int IndexOfDecl;
 };
 
-template <class T>
-static FriendCountAndPosition getFriendCountAndPosition(
-    const FriendDecl *FD,
-    llvm::function_ref<T(const FriendDecl *)> GetCanTypeOrDecl) {
+static bool IsEquivalentFriend(ASTImporter &Importer, FriendDecl *FD1,
+                               FriendDecl *FD2) {
+  if ((!FD1->getFriendType()) != (!FD2->getFriendType()))
+    return false;
+
+  if (const TypeSourceInfo *TSI = FD1->getFriendType())
+    return Importer.IsStructurallyEquivalent(
+        TSI->getType(), FD2->getFriendType()->getType(), /*Complain=*/false);
+
+  ASTImporter::NonEquivalentDeclSet NonEquivalentDecls;
+  StructuralEquivalenceContext Ctx(
+      FD1->getASTContext(), FD2->getASTContext(), NonEquivalentDecls,
+      StructuralEquivalenceKind::Default,
+      /* StrictTypeSpelling = */ false, /* Complain = */ false);
+  return Ctx.IsEquivalent(FD1, FD2);
+}
+
+static FriendCountAndPosition getFriendCountAndPosition(ASTImporter &Importer,
+                                                        FriendDecl *FD) {
   unsigned int FriendCount = 0;
   std::optional<unsigned int> FriendPosition;
   const auto *RD = cast<CXXRecordDecl>(FD->getLexicalDeclContext());
 
-  T TypeOrDecl = GetCanTypeOrDecl(FD);
-
-  for (const FriendDecl *FoundFriend : RD->friends()) {
+  for (FriendDecl *FoundFriend : RD->friends()) {
     if (FoundFriend == FD) {
       FriendPosition = FriendCount;
       ++FriendCount;
-    } else if (!FoundFriend->getFriendDecl() == !FD->getFriendDecl() &&
-               GetCanTypeOrDecl(FoundFriend) == TypeOrDecl) {
+    } else if (IsEquivalentFriend(Importer, FD, FoundFriend)) {
       ++FriendCount;
     }
   }
@@ -4104,21 +4116,6 @@ static FriendCountAndPosition getFriendCountAndPosition(
   return {FriendCount, *FriendPosition};
 }
 
-static FriendCountAndPosition getFriendCountAndPosition(const FriendDecl *FD) {
-  if (FD->getFriendType())
-    return getFriendCountAndPosition<QualType>(FD, [](const FriendDecl *F) {
-      if (TypeSourceInfo *TSI = F->getFriendType())
-        return TSI->getType().getCanonicalType();
-      llvm_unreachable("Wrong friend object type.");
-    });
-  else
-    return getFriendCountAndPosition<Decl *>(FD, [](const FriendDecl *F) {
-      if (Decl *D = F->getFriendDecl())
-        return D->getCanonicalDecl();
-      llvm_unreachable("Wrong friend object type.");
-    });
-}
-
 ExpectedDecl ASTNodeImporter::VisitFriendDecl(FriendDecl *D) {
   // Import the major distinguishing characteristics of a declaration.
   DeclContext *DC, *LexicalDC;
@@ -4129,26 +4126,13 @@ ExpectedDecl ASTNodeImporter::VisitFriendDecl(FriendDecl *D) {
   // FriendDecl is not a NamedDecl so we cannot use lookup.
   // We try to maintain order and count of redundant friend declarations.
   const auto *RD = cast<CXXRecordDecl>(DC);
-  FriendDecl *ImportedFriend = RD->getFirstFriend();
   SmallVector<FriendDecl *, 2> ImportedEquivalentFriends;
-
-  while (ImportedFriend) {
-    bool Match = false;
-    if (D->getFriendDecl() && ImportedFriend->getFriendDecl()) {
-      Match =
-          IsStructuralMatch(D->getFriendDecl(), ImportedFriend->getFriendDecl(),
-                            /*Complain=*/false);
-    } else if (D->getFriendType() && ImportedFriend->getFriendType()) {
-      Match = Importer.IsStructurallyEquivalent(
-          D->getFriendType()->getType(),
-          ImportedFriend->getFriendType()->getType(), /*Complain=*/false);
-    }
-    if (Match)
+  for (FriendDecl *ImportedFriend : RD->friends())
+    if (IsEquivalentFriend(Importer, D, ImportedFriend))
       ImportedEquivalentFriends.push_back(ImportedFriend);
 
-    ImportedFriend = ImportedFriend->getNextFriend();
-  }
-  FriendCountAndPosition CountAndPosition = getFriendCountAndPosition(D);
+  FriendCountAndPosition CountAndPosition =
+      getFriendCountAndPosition(Importer, D);
 
   assert(ImportedEquivalentFriends.size() <= CountAndPosition.TotalCount &&
          "Class with non-matching friends is imported, ODR check wrong?");

clang/unittests/AST/ASTImporterTest.cpp

@@ -4054,6 +4054,25 @@ struct ImportFriendClasses : ASTImporterOptionSpecificTestBase {
                      ->lookup(ToRecordOfFriend->getDeclName())
                      .empty());
   }
+
+  void testRepeatedFriendImport(const char *Code) {
+    Decl *ToTu = getToTuDecl(Code, Lang_CXX03);
+    Decl *FromTu = getTuDecl(Code, Lang_CXX03, "from.cc");
+
+    auto *ToFriend1 = FirstDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
+    auto *ToFriend2 = LastDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
+    auto *FromFriend1 =
+        FirstDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
+    auto *FromFriend2 =
+        LastDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
+
+    FriendDecl *ToImportedFriend1 = Import(FromFriend1, Lang_CXX03);
+    FriendDecl *ToImportedFriend2 = Import(FromFriend2, Lang_CXX03);
+
+    EXPECT_NE(ToImportedFriend1, ToImportedFriend2);
+    EXPECT_EQ(ToFriend1, ToImportedFriend1);
+    EXPECT_EQ(ToFriend2, ToImportedFriend2);
+  }
 };
 
 TEST_P(ImportFriendClasses, ImportOfFriendRecordDoesNotMergeDefinition) {
@@ -4395,21 +4414,7 @@ TEST_P(ImportFriendClasses, ImportOfRepeatedFriendType) {
         friend class X;
       };
       )";
-  Decl *ToTu = getToTuDecl(Code, Lang_CXX03);
-  Decl *FromTu = getTuDecl(Code, Lang_CXX03, "from.cc");
-
-  auto *ToFriend1 = FirstDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
-  auto *ToFriend2 = LastDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
-  auto *FromFriend1 =
-      FirstDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
-  auto *FromFriend2 = LastDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
-
-  FriendDecl *ToImportedFriend1 = Import(FromFriend1, Lang_CXX03);
-  FriendDecl *ToImportedFriend2 = Import(FromFriend2, Lang_CXX03);
-
-  EXPECT_NE(ToImportedFriend1, ToImportedFriend2);
-  EXPECT_EQ(ToFriend1, ToImportedFriend1);
-  EXPECT_EQ(ToFriend2, ToImportedFriend2);
+  testRepeatedFriendImport(Code);
 }
 
 TEST_P(ImportFriendClasses, ImportOfRepeatedFriendDecl) {
@@ -4420,21 +4425,31 @@ TEST_P(ImportFriendClasses, ImportOfRepeatedFriendDecl) {
         friend void f();
       };
       )";
-  Decl *ToTu = getToTuDecl(Code, Lang_CXX03);
-  Decl *FromTu = getTuDecl(Code, Lang_CXX03, "from.cc");
-
-  auto *ToFriend1 = FirstDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
-  auto *ToFriend2 = LastDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
-  auto *FromFriend1 =
-      FirstDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
-  auto *FromFriend2 = LastDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
+  testRepeatedFriendImport(Code);
+}
 
-  FriendDecl *ToImportedFriend1 = Import(FromFriend1, Lang_CXX03);
-  FriendDecl *ToImportedFriend2 = Import(FromFriend2, Lang_CXX03);
+TEST_P(ImportFriendClasses, ImportOfRepeatedFriendFunctionTemplateDecl) {
+  const char *Code =
+      R"(
+        template <class T>
+        class Container {
+          template <class U> friend void m();
+          template <class U> friend void m();
+        };
+      )";
+  testRepeatedFriendImport(Code);
+}
 
-  EXPECT_NE(ToImportedFriend1, ToImportedFriend2);
-  EXPECT_EQ(ToFriend1, ToImportedFriend1);
-  EXPECT_EQ(ToFriend2, ToImportedFriend2);
+TEST_P(ImportFriendClasses, ImportOfRepeatedFriendClassTemplateDecl) {
+  const char *Code =
+      R"(
+        template <class T>
+        class Container {
+          template <class U> friend class X;
+          template <class U> friend class X;
+        };
+      )";
+  testRepeatedFriendImport(Code);
 }
 
 TEST_P(ASTImporterOptionSpecificTestBase, FriendFunInClassTemplate) {