Skip to content

Commit

Permalink
[clang][ASTImporter] Improve import of friend class templates. (llvm#…
Browse files Browse the repository at this point in the history 
…74627)

A friend template that is in a dependent context is not linked into
declaration chains (for example with the definition of the befriended
template). This condition was not correctly handled by `ASTImporter`.
  • Loading branch information
@balazske
balazske committed Jan 11, 2024
1 parent 1de3f46 commit 4b0314d
Show file tree
Hide file tree
Showing 2 changed files with 173 additions and 7 deletions.
24 changes: 17 additions & 7 deletions clang/lib/AST/ASTImporter.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5929,15 +5929,22 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
if (ToD)
return ToD;

bool IsFriendTemplate = D->getFriendObjectKind() != Decl::FOK_None;
bool IsDependentContext = DC != LexicalDC ? LexicalDC->isDependentContext()
: DC->isDependentContext();
bool DependentFriend = IsFriendTemplate && IsDependentContext;
// Should check if a declaration is friend in a dependent context.
// Such templates are not linked together in a declaration chain.
// The ASTImporter strategy is to map existing forward declarations to
// imported ones only if strictly necessary, otherwise import these as new
// forward declarations. In case of the "dependent friend" declarations, new
// declarations are created, but not linked in a declaration chain.
auto IsDependentFriend = [](ClassTemplateDecl *TD) {
return TD->getFriendObjectKind() != Decl::FOK_None &&
TD->getLexicalDeclContext()->isDependentContext();
};
bool DependentFriend = IsDependentFriend(D);

ClassTemplateDecl *FoundByLookup = nullptr;

// We may already have a template of the same name; try to find and match it.
if (!DependentFriend && !DC->isFunctionOrMethod()) {
if (!DC->isFunctionOrMethod()) {
SmallVector<NamedDecl *, 4> ConflictingDecls;
auto FoundDecls = Importer.findDeclsInToCtx(DC, Name);
for (auto *FoundDecl : FoundDecls) {
Expand All @@ -5953,10 +5960,13 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {

// FIXME: sufficient conditon for 'IgnoreTemplateParmDepth'?
bool IgnoreTemplateParmDepth =
FoundTemplate->getFriendObjectKind() != Decl::FOK_None &&
!D->specializations().empty();
(FoundTemplate->getFriendObjectKind() != Decl::FOK_None) !=
(D->getFriendObjectKind() != Decl::FOK_None);
if (IsStructuralMatch(D, FoundTemplate, /*Complain=*/true,
IgnoreTemplateParmDepth)) {
if (DependentFriend || IsDependentFriend(FoundTemplate))
continue;

ClassTemplateDecl *TemplateWithDef =
getTemplateDefinition(FoundTemplate);
if (D->isThisDeclarationADefinition() && TemplateWithDef)
Expand Down
156 changes: 156 additions & 0 deletions clang/unittests/AST/ASTImporterTest.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4540,6 +4540,162 @@ TEST_P(ImportFriendClasses, ImportOfClassDefinitionAndFwdFriendShouldBeLinked) {
EXPECT_EQ(ImportedFwd, ImportedDef->getPreviousDecl());
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_DefToFriend) {
Decl *ToTU = getToTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03);
auto *ToYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
ToTU, classTemplateDecl(hasName("Y")));
Decl *FromTU = getTuDecl(
R"(
template<class T1>
struct Y {};
)",
Lang_CXX03, "input0.cc");
auto *FromYDef = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYDef = Import(FromYDef, Lang_CXX03);
EXPECT_TRUE(ImportedYDef);
EXPECT_FALSE(ImportedYDef->getPreviousDecl());
EXPECT_NE(ImportedYDef, ToYFriend);
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_DefToFriend_NE) {
getToTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03);
Decl *FromTU = getTuDecl(
R"(
template<class T1, class T2>
struct Y {};
)",
Lang_CXX03, "input0.cc");
auto *FromYDef = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYDef = Import(FromYDef, Lang_CXX03);
EXPECT_FALSE(ImportedYDef);
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_FriendToFriend) {
Decl *ToTU = getToTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03);
auto *ToYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
ToTU, classTemplateDecl(hasName("Y")));
Decl *FromTU = getTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03, "input0.cc");
auto *FromYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYFriend = Import(FromYFriend, Lang_CXX03);
EXPECT_TRUE(ImportedYFriend);
EXPECT_FALSE(ImportedYFriend->getPreviousDecl());
EXPECT_NE(ImportedYFriend, ToYFriend);
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_FriendToFriend_NE) {
getToTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03);
Decl *FromTU = getTuDecl(
R"(
template<class T1>
struct X {
template<class T2, class T3>
friend struct Y;
};
)",
Lang_CXX03, "input0.cc");
auto *FromYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYFriend = Import(FromYFriend, Lang_CXX03);
EXPECT_FALSE(ImportedYFriend);
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_FriendToDef) {
Decl *ToTU = getToTuDecl(
R"(
template<class T1>
struct Y {};
)",
Lang_CXX03);
auto *ToYDef = FirstDeclMatcher<ClassTemplateDecl>().match(
ToTU, classTemplateDecl(hasName("Y")));
Decl *FromTU = getTuDecl(
R"(
template<class T1>
struct X {
template<class T2>
friend struct Y;
};
)",
Lang_CXX03, "input0.cc");
auto *FromYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYFriend = Import(FromYFriend, Lang_CXX03);
EXPECT_TRUE(ImportedYFriend);
EXPECT_FALSE(ImportedYFriend->getPreviousDecl());
EXPECT_NE(ImportedYFriend, ToYDef);
}

TEST_P(ImportFriendClasses,
ImportFriendTemplatesInDependentContext_FriendToDef_NE) {
getToTuDecl(
R"(
template<class T1>
struct Y {};
)",
Lang_CXX03);
Decl *FromTU = getTuDecl(
R"(
template<class T1>
struct X {
template<class T2, class T3>
friend struct Y;
};
)",
Lang_CXX03, "input0.cc");
auto *FromYFriend = FirstDeclMatcher<ClassTemplateDecl>().match(
FromTU, classTemplateDecl(hasName("Y")));
auto *ImportedYFriend = Import(FromYFriend, Lang_CXX03);
EXPECT_FALSE(ImportedYFriend);
}

TEST_P(ImportFriendClasses, ImportOfRepeatedFriendType) {
const char *Code =
R"(
Expand Down

0 comments on commit 4b0314d

Please sign in to comment.