[Bug c++/100172] ICE with "concept concept" keyword in struct

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100172

--- Comment #1 from 康桓瑋 <hewillk at gmail dot com> ---
And gcc-trunk accepts this non-sense snippet:

https://godbolt.org/z/PbTa55eTx

void f(auto) {
  struct S {
    concept enum E {};
  };
  []() requires S::E {};
}

template void f(int);