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[Clang] Fix the mangling of lambdas (llvm#89204)
Lambdas used in the initializer of a local class were not mangling the name of the member. Fixes llvm#88906
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‎clang/docs/ReleaseNotes.rst‎

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@@ -549,6 +549,7 @@ Bug Fixes to C++ Support
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- Fix a crash in requires expression with templated base class member function. Fixes (#GH84020).
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- Fix a crash caused by defined struct in a type alias template when the structure
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has fields with dependent type. Fixes (#GH75221).
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- Fix the Itanium mangling of lambdas defined in a member of a local class (#GH88906)
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Bug Fixes to AST Handling
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^^^^^^^^^^^^^^^^^^^^^^^^^

‎clang/include/clang/Basic/LangOptions.h‎

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@@ -224,6 +224,11 @@ class LangOptionsBase {
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/// - the parameter list of a template template parameter
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Ver17,
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/// Attempt to be ABI-compatible with code generated by Clang 18.0.x.
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/// This causes clang to revert some fixes to the mangling of lambdas
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/// in the initializers of members of local classes.
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Ver18,
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/// Conform to the underlying platform's C and C++ ABIs as closely
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/// as we can.
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Latest

‎clang/lib/AST/ItaniumMangle.cpp‎

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@@ -1062,33 +1062,35 @@ void CXXNameMangler::mangleNameWithAbiTags(GlobalDecl GD,
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// ::= <local-name>
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//
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const DeclContext *DC = Context.getEffectiveDeclContext(ND);
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bool IsLambda = isLambda(ND);
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// If this is an extern variable declared locally, the relevant DeclContext
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// is that of the containing namespace, or the translation unit.
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// FIXME: This is a hack; extern variables declared locally should have
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// a proper semantic declaration context!
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if (isLocalContainerContext(DC) && ND->hasLinkage() && !isLambda(ND))
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if (isLocalContainerContext(DC) && ND->hasLinkage() && !IsLambda)
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while (!DC->isNamespace() && !DC->isTranslationUnit())
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DC = Context.getEffectiveParentContext(DC);
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else if (GetLocalClassDecl(ND)) {
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else if (GetLocalClassDecl(ND) &&
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(!IsLambda || isCompatibleWith(LangOptions::ClangABI::Ver18))) {
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mangleLocalName(GD, AdditionalAbiTags);
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return;
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}
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assert(!isa<LinkageSpecDecl>(DC) && "context cannot be LinkageSpecDecl");
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if (isLocalContainerContext(DC)) {
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mangleLocalName(GD, AdditionalAbiTags);
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return;
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}
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// Closures can require a nested-name mangling even if they're semantically
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// in the global namespace.
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if (const NamedDecl *PrefixND = getClosurePrefix(ND)) {
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mangleNestedNameWithClosurePrefix(GD, PrefixND, AdditionalAbiTags);
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return;
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}
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if (isLocalContainerContext(DC)) {
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mangleLocalName(GD, AdditionalAbiTags);
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return;
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}
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if (DC->isTranslationUnit() || isStdNamespace(DC)) {
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// Check if we have a template.
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const TemplateArgumentList *TemplateArgs = nullptr;
@@ -2201,8 +2203,6 @@ void CXXNameMangler::manglePrefix(const DeclContext *DC, bool NoFunction) {
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if (NoFunction && isLocalContainerContext(DC))
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return;
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assert(!isLocalContainerContext(DC));
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const NamedDecl *ND = cast<NamedDecl>(DC);
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if (mangleSubstitution(ND))
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return;

‎clang/lib/Frontend/CompilerInvocation.cpp‎

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@@ -3660,6 +3660,9 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
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case LangOptions::ClangABI::Ver17:
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GenerateArg(Consumer, OPT_fclang_abi_compat_EQ, "17.0");
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break;
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case LangOptions::ClangABI::Ver18:
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GenerateArg(Consumer, OPT_fclang_abi_compat_EQ, "18.0");
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break;
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case LangOptions::ClangABI::Latest:
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break;
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}
@@ -4167,6 +4170,8 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
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Opts.setClangABICompat(LangOptions::ClangABI::Ver15);
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else if (Major <= 17)
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Opts.setClangABICompat(LangOptions::ClangABI::Ver17);
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else if (Major <= 18)
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Opts.setClangABICompat(LangOptions::ClangABI::Ver18);
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} else if (Ver != "latest") {
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Diags.Report(diag::err_drv_invalid_value)
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<< A->getAsString(Args) << A->getValue();

‎clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp‎

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@@ -0,0 +1,46 @@
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// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -emit-llvm -mconstructor-aliases -o - | FileCheck %s
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// RUN: %clang_cc1 -triple x86_64-linux-gnu -fclang-abi-compat=18 %s -emit-llvm -mconstructor-aliases -o - | FileCheck --check-prefix=CLANG18 %s
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// RUN: %clang_cc1 -triple i386-pc-win32 %s -emit-llvm -mconstructor-aliases -o - | FileCheck --check-prefix=MSABI %s
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class func {
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public:
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template <typename T>
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func(T){};
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template <typename T, typename U>
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func(T, U){};
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};
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void GH88906(){
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class Test{
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public:
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func a{[]{ }, []{ }};
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func b{[]{ }};
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func c{[]{ }};
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} test;
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}
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// CHECK-LABEL: define internal void @_ZZ7GH88906vEN4TestC2Ev
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// CHECK: call void @_ZN4funcC2IN7GH889064Test1aMUlvE_ENS3_UlvE0_EEET_T0_
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// CHECK: call void @_ZN4funcC2IN7GH889064Test1bMUlvE_EEET_
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// CHECK: call void @_ZN4funcC2IN7GH889064Test1cMUlvE_EEET_
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// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1aMUlvE_ENS3_UlvE0_EEET_T0_
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// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1bMUlvE_EEET_
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// CHECK-LABEL: define internal void @_ZN4funcC2IN7GH889064Test1cMUlvE_EEET_
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// CLANG18-LABEL: define internal void @_ZZ7GH88906vEN4TestC2Ev
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// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EZ7GH88906vENS1_UlvE0_EEET_T0_
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// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EEET_
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// CLANG18: call void @_ZN4funcC2IZ7GH88906vEN4TestUlvE_EEET_
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// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??0Test@?1??GH88906@@YAXXZ@QAE@XZ"
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// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@12?1??3@YAXXZ@@func@@QAE@V<lambda_1>@a@Test@?1??GH88906@@YAXXZ@V<lambda_2>@23?1??4@YAXXZ@@Z"
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// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@Z"
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// MSABI: call x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@Z"
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// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?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"
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// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@b@Test@?1??GH88906@@YAXXZ@@Z"
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// MSABI-LABEL: define internal x86_thiscallcc noundef ptr @"??$?0V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@func@@QAE@V<lambda_1>@c@Test@?1??GH88906@@YAXXZ@@Z"

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