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[clang][ASTImporter] Improve import of friend class templates. #74627

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Merged
merged 4 commits into from
Jan 11, 2024
Merged

[clang][ASTImporter] Improve import of friend class templates. #74627

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cbcb81e
[clang][ASTImporter] Improve import of friend class templates.
balazske Dec 5, 2023
5f4ec0c
fix formatting error
balazske Dec 6, 2023
0e63ed1
removed unused variables
balazske Dec 13, 2023
459603b
simplified 'IsDependentFriend'
balazske Jan 9, 2024
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24 changes: 17 additions & 7 deletions clang/lib/AST/ASTImporter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5919,15 +5919,22 @@ 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 @@ -5943,10 +5950,13 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {

// FIXME: sufficient conditon for 'IgnoreTemplateParmDepth'?
bool IgnoreTemplateParmDepth =
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Change of this condition was needed to make a failing test ImportOfRecursiveFriendClassTemplateWithNonTypeParm to pass.

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
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Original file line number Diff line number Diff line change
Expand Up @@ -4528,6 +4528,162 @@ 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