[ASTImporter] Friend class decl should not be visible in its context

Summary:
In the past we had to use DeclContext::makeDeclVisibleInContext to make
friend declarations available for subsequent lookup calls and this way
we could chain (redecl) the structurally equivalent decls.
By doing this we created an AST that improperly made declarations
visible in some contexts, so the AST was malformed.
Since we use the importer specific lookup this is no longer necessary,
because with that we can find every previous nodes.

Reviewers: balazske, a_sidorin, a.sidorin, shafik

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71020

1 files changed, 44 insertions, 6 deletions

diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 6652111fd48..3e8f804374f 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -247,6 +247,11 @@ template <typename T> RecordDecl *getRecordDecl(T *D) {
   return cast<RecordType>(ET->getNamedType().getTypePtr())->getDecl();
 }
 
+static const RecordDecl *getRecordDeclOfFriend(FriendDecl *FD) {
+  QualType Ty = FD->getFriendType()->getType().getCanonicalType();
+  return cast<RecordType>(Ty)->getDecl();
+}
+
 struct ImportExpr : TestImportBase {};
 struct ImportType : TestImportBase {};
 struct ImportDecl : TestImportBase {};
@@ -2707,7 +2712,7 @@ TEST_P(ImportFriendFunctions, Lookup) {
   EXPECT_FALSE(To0->isInIdentifierNamespace(Decl::IDNS_Ordinary));
 }
 
-TEST_P(ImportFriendFunctions, DISABLED_LookupWithProtoAfter) {
+TEST_P(ImportFriendFunctions, LookupWithProtoAfter) {
   auto FunctionPattern = functionDecl(hasName("f"));
   auto ClassPattern = cxxRecordDecl(hasName("X"));
 
@@ -3778,6 +3783,44 @@ TEST_P(ImportFriendClasses, ImportOfRecursiveFriendClass) {
   EXPECT_TRUE(MatchVerifier<Decl>{}.match(ToD, Pattern));
 }
 
+TEST_P(ImportFriendClasses, UndeclaredFriendClassShouldNotBeVisible) {
+  Decl *FromTu = getTuDecl("class X { friend class Y; };", Lang_CXX, "from.cc");
+  auto *FromX = FirstDeclMatcher<CXXRecordDecl>().match(
+      FromTu, cxxRecordDecl(hasName("X")));
+  auto *FromFriend = FirstDeclMatcher<FriendDecl>().match(FromTu, friendDecl());
+  RecordDecl *FromRecordOfFriend =
+      const_cast<RecordDecl *>(getRecordDeclOfFriend(FromFriend));
+
+  ASSERT_EQ(FromRecordOfFriend->getDeclContext(), cast<DeclContext>(FromTu));
+  ASSERT_EQ(FromRecordOfFriend->getLexicalDeclContext(),
+            cast<DeclContext>(FromX));
+  ASSERT_FALSE(
+      FromRecordOfFriend->getDeclContext()->containsDecl(FromRecordOfFriend));
+  ASSERT_FALSE(FromRecordOfFriend->getLexicalDeclContext()->containsDecl(
+      FromRecordOfFriend));
+  ASSERT_FALSE(FromRecordOfFriend->getLookupParent()
+                   ->lookup(FromRecordOfFriend->getDeclName())
+                   .empty());
+
+  auto *ToX = Import(FromX, Lang_CXX);
+  ASSERT_TRUE(ToX);
+
+  Decl *ToTu = ToX->getTranslationUnitDecl();
+  auto *ToFriend = FirstDeclMatcher<FriendDecl>().match(ToTu, friendDecl());
+  RecordDecl *ToRecordOfFriend =
+      const_cast<RecordDecl *>(getRecordDeclOfFriend(ToFriend));
+
+  ASSERT_EQ(ToRecordOfFriend->getDeclContext(), cast<DeclContext>(ToTu));
+  ASSERT_EQ(ToRecordOfFriend->getLexicalDeclContext(), cast<DeclContext>(ToX));
+  EXPECT_FALSE(
+      ToRecordOfFriend->getDeclContext()->containsDecl(ToRecordOfFriend));
+  EXPECT_FALSE(ToRecordOfFriend->getLexicalDeclContext()->containsDecl(
+      ToRecordOfFriend));
+  EXPECT_FALSE(ToRecordOfFriend->getLookupParent()
+                   ->lookup(ToRecordOfFriend->getDeclName())
+                   .empty());
+}
+
 TEST_P(ImportFriendClasses, ImportOfRecursiveFriendClassTemplate) {
   Decl *FromTu = getTuDecl(
       R"(
@@ -4477,11 +4520,6 @@ TEST_P(ASTImporterLookupTableTest, LookupDeclNamesFromDifferentTUs) {
   ASSERT_EQ(Res.size(), 0u);
 }
 
-static const RecordDecl *getRecordDeclOfFriend(FriendDecl *FD) {
-  QualType Ty = FD->getFriendType()->getType().getCanonicalType();
-  return cast<RecordType>(Ty)->getDecl();
-}
-
 TEST_P(ASTImporterLookupTableTest,
        LookupFindsFwdFriendClassDeclWithElaboratedType) {
   TranslationUnitDecl *ToTU = getToTuDecl(