https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111113
Bug ID: 111113
Summary: Cannot define friend function of a local class in
namespace scope
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This program defines friend function of a local class in namespace scope:
auto foo() {
struct A;
void bar(const A&);
struct A {
friend void bar(const A&);
};
bar(A{});
return A{};
}
using A = decltype(foo());
void bar(const A&) {}
Both Clang and MSVC permit it, but GCC prints weird errors:
<source>:5:21: error: 'void bar(const foo()::A&)', declared using local type
'const foo()::A', is used but never defined [-fpermissive]
5 | friend void bar(const A&);
| ^~~
<source>:5:21: error: 'void bar(const foo()::A&)' used but never defined
<source>:12:6: warning: 'void bar(const A&)' defined but not used
Online demo: https://godbolt.org/z/Yqoeda94x
