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[Clang] Fix the mangling of lambdas #89204

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Merged
merged 3 commits into from
Apr 19, 2024
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[Clang] Fix the mangling of lambdas #89204

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6382171
[Clang] Fix the mangling of lambdas
cor3ntin Apr 18, 2024
4e7b776
ms abi tests
cor3ntin Apr 18, 2024
1a454e2
Add ABI tag
cor3ntin Apr 18, 2024
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1 change: 1 addition & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -538,6 +538,7 @@ Bug Fixes to C++ Support
- Fix a crash in requires expression with templated base class member function. Fixes (#GH84020).
- Fix a crash caused by defined struct in a type alias template when the structure
has fields with dependent type. Fixes (#GH75221).
- Fix the Itanium mangling of lambdas defined in a member of a local class (#GH88906)
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@rjmccall do you think this should come with an ABI tag to get the old mangling behavior?


Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
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5 changes: 5 additions & 0 deletions clang/include/clang/Basic/LangOptions.h
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Expand Up @@ -224,6 +224,11 @@ class LangOptionsBase {
/// - the parameter list of a template template parameter
Ver17,

/// Attempt to be ABI-compatible with code generated by Clang 18.0.x.
/// This causes clang to revert some fixes to the mangling of lambdas
/// in the initializers of members of local classes.
Ver18,

/// Conform to the underlying platform's C and C++ ABIs as closely
/// as we can.
Latest
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18 changes: 9 additions & 9 deletions clang/lib/AST/ItaniumMangle.cpp
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Expand Up @@ -1062,33 +1062,35 @@ void CXXNameMangler::mangleNameWithAbiTags(GlobalDecl GD,
// ::= <local-name>
//
const DeclContext *DC = Context.getEffectiveDeclContext(ND);
bool IsLambda = isLambda(ND);

// If this is an extern variable declared locally, the relevant DeclContext
// is that of the containing namespace, or the translation unit.
// FIXME: This is a hack; extern variables declared locally should have
// a proper semantic declaration context!
if (isLocalContainerContext(DC) && ND->hasLinkage() && !isLambda(ND))
if (isLocalContainerContext(DC) && ND->hasLinkage() && !IsLambda)
while (!DC->isNamespace() && !DC->isTranslationUnit())
DC = Context.getEffectiveParentContext(DC);
else if (GetLocalClassDecl(ND)) {
else if (GetLocalClassDecl(ND) &&
(!IsLambda || isCompatibleWith(LangOptions::ClangABI::Ver18))) {
mangleLocalName(GD, AdditionalAbiTags);
return;
}

assert(!isa<LinkageSpecDecl>(DC) && "context cannot be LinkageSpecDecl");

if (isLocalContainerContext(DC)) {
mangleLocalName(GD, AdditionalAbiTags);
return;
}

// Closures can require a nested-name mangling even if they're semantically
// in the global namespace.
if (const NamedDecl *PrefixND = getClosurePrefix(ND)) {
mangleNestedNameWithClosurePrefix(GD, PrefixND, AdditionalAbiTags);
return;
}

if (isLocalContainerContext(DC)) {
mangleLocalName(GD, AdditionalAbiTags);
return;
}

if (DC->isTranslationUnit() || isStdNamespace(DC)) {
// Check if we have a template.
const TemplateArgumentList *TemplateArgs = nullptr;
Expand Down Expand Up @@ -2201,8 +2203,6 @@ void CXXNameMangler::manglePrefix(const DeclContext *DC, bool NoFunction) {
if (NoFunction && isLocalContainerContext(DC))
return;

assert(!isLocalContainerContext(DC));

const NamedDecl *ND = cast<NamedDecl>(DC);
if (mangleSubstitution(ND))
return;
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5 changes: 5 additions & 0 deletions clang/lib/Frontend/CompilerInvocation.cpp
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Expand Up @@ -3655,6 +3655,9 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
case LangOptions::ClangABI::Ver17:
GenerateArg(Consumer, OPT_fclang_abi_compat_EQ, "17.0");
break;
case LangOptions::ClangABI::Ver18:
GenerateArg(Consumer, OPT_fclang_abi_compat_EQ, "18.0");
break;
case LangOptions::ClangABI::Latest:
break;
}
Expand Down Expand Up @@ -4162,6 +4165,8 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
Opts.setClangABICompat(LangOptions::ClangABI::Ver15);
else if (Major <= 17)
Opts.setClangABICompat(LangOptions::ClangABI::Ver17);
else if (Major <= 18)
Opts.setClangABICompat(LangOptions::ClangABI::Ver18);
} else if (Ver != "latest") {
Diags.Report(diag::err_drv_invalid_value)
<< A->getAsString(Args) << A->getValue();
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46 changes: 46 additions & 0 deletions clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp
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@@ -0,0 +1,46 @@
// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -emit-llvm -mconstructor-aliases -o - | FileCheck %s
// RUN: %clang_cc1 -triple x86_64-linux-gnu -fclang-abi-compat=18 %s -emit-llvm -mconstructor-aliases -o - | FileCheck --check-prefix=CLANG18 %s
// RUN: %clang_cc1 -triple i386-pc-win32 %s -emit-llvm -mconstructor-aliases -o - | FileCheck --check-prefix=MSABI %s


class func {
public:
template <typename T>
func(T){};
template <typename T, typename U>
func(T, U){};
};

void GH88906(){
class Test{
public:
func a{[]{ }, []{ }};
func b{[]{ }};
func c{[]{ }};
} test;
}

// CHECK-LABEL: define internal void @_ZZ7GH88906vEN4TestC2Ev
// CHECK: call void @_ZN4funcC2IN7GH889064Test1aMUlvE_ENS3_UlvE0_EEET_T0_
// CHECK: call void @_ZN4funcC2IN7GH889064Test1bMUlvE_EEET_
// CHECK: call void @_ZN4funcC2IN7GH889064Test1cMUlvE_EEET_

// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1aMUlvE_ENS3_UlvE0_EEET_T0_
// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1bMUlvE_EEET_
// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1cMUlvE_EEET_

// CLANG18-LABEL: define internal void @_ZZ7GH88906vEN4TestC2Ev
// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EZ7GH88906vENS1_UlvE0_EEET_T0_
// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EEET_
// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EEET_



// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??0Test@?1??GH88906@@YAXXZ@QAE@XZ"
// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@12?1??3@YAXXZ@@func@@QAE@V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@23?1??4@YAXXZ@@Z"
// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@Z"
// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@Z"

// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@12?1??3@YAXXZ@@func@@QAE@V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@23?1??4@YAXXZ@@Z"
// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@Z"
// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@Z"