https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109426
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- N.B. this code is just copied from PR 54402. It might have been helpful to say where you found the code. zhonghao, it's really not helpful to just copy&paste code that you don't understand into bug reports with stupid, incorrect claims like "while expanding templates". Maybe you're trying to be helpful, but you're just wasting our time.
