https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102791
Bug ID: 102791
Summary: Friend declaration of lambda function is ignored
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This is a valid program:
```
constexpr auto f = [](auto& x){
x.m();
};
class A{
friend decltype(f);
void m() {}
public:
void n() {
f(*this);
}
};
int main(){
A{}.n();
}
```
which is accepted by Clang and MSVC, but unfortunately not by GCC.
The error is
```
error: 'void A::m()' is private within this context
2 | x.m();
```
Demo: https://gcc.godbolt.org/z/vKnhqG9b1
Related discussion: https://stackoverflow.com/q/64390688/7325599
