[Clang] Fix the mangling of lambdas

[cor3ntin]

Lambdas used in the initializer of a local class were not mangling the name of the member.

Fixes #88906

[llvmbot]

@llvm/pr-subscribers-clang

Author: cor3ntin (cor3ntin)

Changes

Lambdas used in the initializer of a local class were not mangling the name of the member.

Fixes #88906

---

Full diff: https://github.com/llvm/llvm-project/pull/89204.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/AST/ItaniumMangle.cpp (+8-10)
• (added) clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp (+27)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 6c51c2d1f483ce..0ad301b24e6b73 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -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)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index c3b98d2d2149cb..53ef022c710d8d 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -1070,14 +1070,7 @@ void CXXNameMangler::mangleNameWithAbiTags(GlobalDecl GD,
   if (isLocalContainerContext(DC) && ND->hasLinkage() && !isLambda(ND))
     while (!DC->isNamespace() && !DC->isTranslationUnit())
       DC = Context.getEffectiveParentContext(DC);
-  else if (GetLocalClassDecl(ND)) {
-    mangleLocalName(GD, AdditionalAbiTags);
-    return;
-  }
-
-  assert(!isa<LinkageSpecDecl>(DC) && "context cannot be LinkageSpecDecl");
-
-  if (isLocalContainerContext(DC)) {
+  else if (GetLocalClassDecl(ND) && !isLambda(ND)) {
     mangleLocalName(GD, AdditionalAbiTags);
     return;
   }
@@ -1089,6 +1082,13 @@ void CXXNameMangler::mangleNameWithAbiTags(GlobalDecl GD,
     return;
   }
 
+  assert(!isa<LinkageSpecDecl>(DC) && "context cannot be LinkageSpecDecl");
+
+  if (isLocalContainerContext(DC)) {
+    mangleLocalName(GD, AdditionalAbiTags);
+    return;
+  }
+
   if (DC->isTranslationUnit() || isStdNamespace(DC)) {
     // Check if we have a template.
     const TemplateArgumentList *TemplateArgs = nullptr;
@@ -2201,8 +2201,6 @@ 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;
diff --git a/clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp b/clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp
new file mode 100644
index 00000000000000..61f340c848ebe4
--- /dev/null
+++ b/clang/test/CodeGenCXX/mangle-lambdas-gh88906.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -emit-llvm -o - | FileCheck %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_

[AaronBallman]

@rjmccall do you think this should come with an ABI tag to get the old mangling behavior?