https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99505
--- Comment #2 from 康桓瑋 <hewillk at gmail dot com> --- Yep, wandbox (https://wandbox.org/permlink/OUJpCz6dFrlA1vod) compiles fine. This invalid code maybe can reproduce that locally. int main() { [] (decltype([]{})) {} (); } (wandbox: https://wandbox.org/permlink/re9O9DXwoaYmNInd) (godbolt: https://godbolt.org/z/e4e7or)