[Bug c++/91380] Requesting a better diagnostic for dumb include mistake

[barry.revzin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91380

--- Comment #3 from Barry Revzin <barry.revzin at gmail dot com> ---
In case it's at all helpful, here's the clang review that Tim found for this
diagnostic: https://reviews.llvm.org/D51333