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[clang][ASTImporter] Allow import of similar friend template with different depth #115734

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Merged
merged 3 commits into from
Dec 2, 2024
Merged

[clang][ASTImporter] Allow import of similar friend template with different depth #115734

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eca94b1
[clang][ASTImporter] Allow import of similar friend template with dif…
balazske Nov 11, 2024
4044dc6
Merge branch 'main' into astimporter_friendtemplimport
balazske Nov 15, 2024
ff007ab
fixed test code
balazske Nov 15, 2024
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16 changes: 14 additions & 2 deletions clang/lib/AST/ASTImporter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6095,8 +6095,7 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
Decl::IDNS_TagFriend))
continue;

Decl *Found = FoundDecl;
auto *FoundTemplate = dyn_cast<ClassTemplateDecl>(Found);
auto *FoundTemplate = dyn_cast<ClassTemplateDecl>(FoundDecl);
if (FoundTemplate) {
if (!hasSameVisibilityContextAndLinkage(FoundTemplate, D))
continue;
Expand All @@ -6120,6 +6119,19 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
// see ASTTests test ImportExistingFriendClassTemplateDef.
continue;
}
// When importing a friend, it is possible that multiple declarations
// with same name can co-exist in specific cases (if a template contains
// a friend template and has a specialization). For this case the
// declarations should match, except that the "template depth" is
// different. No linking of previous declaration is needed in this case.
// FIXME: This condition may need refinement.
if (D->getFriendObjectKind() != Decl::FOK_None &&
FoundTemplate->getFriendObjectKind() != Decl::FOK_None &&
D->getFriendObjectKind() != FoundTemplate->getFriendObjectKind() &&
IsStructuralMatch(D, FoundTemplate, /*Complain=*/false,
/*IgnoreTemplateParmDepth=*/true))
continue;
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It feels like the logic on 6103 and this here could be merged together? Should IgnoreTemplateParmDepth on 6104 just be changed to also be set if the FriendObjectKind matches? Then I think everything should work out as expected

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I did not want to modify an already working code part when it is not obvious that the change has no effect on the old behavior. In the new case we already know that there is no structural match and depth was not ignored, then we can check if these match with ignored depth (and this second structural equivalence check looks required to not import non-matching friends). We do not need any of the actions in the if branch at line 6108, only a continue (and it is not "dependent friend").


ConflictingDecls.push_back(FoundDecl);
}
}
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105 changes: 105 additions & 0 deletions clang/unittests/AST/ASTImporterTest.cpp
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Expand Up @@ -10181,6 +10181,111 @@ TEST_P(ImportTemplateParmDeclDefaultValue,
FromD, FromDInherited);
}

TEST_P(ASTImporterOptionSpecificTestBase,
ExistingUndeclaredImportDeclaredFriend) {
Decl *ToTU = getToTuDecl(
R"(
template <class A, A>
struct foo;

template <class A>
struct X {
template <class A1, A1>
friend struct foo;
};
)",
Lang_CXX11);
Decl *FromTU = getTuDecl(
R"(
template <class A, A>
struct foo;

template <class A>
struct X {
template <class A1, A1>
friend struct foo;
};

X<int> x;
)",
Lang_CXX11);

auto *ToFr1 = FirstDeclMatcher<FriendDecl>().match(ToTU, friendDecl());
auto *ToFrD1 = ToFr1->getFriendDecl();

auto *FromFr1 = FirstDeclMatcher<FriendDecl>().match(FromTU, friendDecl());
auto *FromFr2 = LastDeclMatcher<FriendDecl>().match(FromTU, friendDecl());

auto *FromFrD1 = FromFr1->getFriendDecl();
auto *FromFrD2 = FromFr2->getFriendDecl();

auto *Ctx1 = cast<Decl>(FromFrD1->getDeclContext());
auto *Ctx2 = cast<Decl>(FromFrD2->getDeclContext());

ASSERT_EQ(Ctx1, Ctx2);
ASSERT_EQ(ToFrD1->getTemplateDepth(), 1u);
ASSERT_EQ(FromFrD2->getTemplateDepth(), 0u);
ASSERT_EQ(ToFrD1->getFriendObjectKind(), Decl::FOK_Undeclared);
ASSERT_EQ(FromFrD2->getFriendObjectKind(), Decl::FOK_Declared);

auto *ToFr2Imp = Import(FromFr2, Lang_CXX11);

EXPECT_TRUE(ToFr2Imp);
}

TEST_P(ASTImporterOptionSpecificTestBase,
ExistingDeclaredImportUndeclaredFriend) {
Decl *ToTU = getToTuDecl(
R"(
template <class A, A>
struct foo;

template <class A>
struct X {
template <class A1, A1>
friend struct foo;
};

X<int> x;
)",
Lang_CXX11);
Decl *FromTU = getTuDecl(
R"(
template <class A, A>
struct foo;

template <class A>
struct X {
template <class A1, A1>
friend struct foo;
};
)",
Lang_CXX11);

auto *ToFr1 = FirstDeclMatcher<FriendDecl>().match(ToTU, friendDecl());
auto *ToFr2 = LastDeclMatcher<FriendDecl>().match(ToTU, friendDecl());

auto *ToFrD1 = ToFr1->getFriendDecl();
auto *ToFrD2 = ToFr2->getFriendDecl();

auto *FromFr1 = FirstDeclMatcher<FriendDecl>().match(FromTU, friendDecl());
auto *FromFrD1 = FromFr1->getFriendDecl();

auto *Ctx1 = cast<Decl>(ToFrD1->getDeclContext());
auto *Ctx2 = cast<Decl>(ToFrD2->getDeclContext());

ASSERT_EQ(Ctx1, Ctx2);
ASSERT_EQ(FromFrD1->getTemplateDepth(), 1u);
ASSERT_EQ(ToFrD2->getTemplateDepth(), 0u);
ASSERT_EQ(FromFrD1->getFriendObjectKind(), Decl::FOK_Undeclared);
ASSERT_EQ(ToFrD2->getFriendObjectKind(), Decl::FOK_Declared);

auto *ToFr1Imp = Import(FromFr1, Lang_CXX11);

EXPECT_TRUE(ToFr1Imp);
EXPECT_EQ(ToFr1Imp, ToFr1);
}

INSTANTIATE_TEST_SUITE_P(ParameterizedTests, ASTImporterLookupTableTest,
DefaultTestValuesForRunOptions);

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