https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91206
--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- There is a known ambiguity in the standard requirements where the argument has the correct promoted type but not the expected type before promotion. I wrote up some notes on this some time ago but didn't submit it as a DR. https://www.polyomino.org.uk/computer/c/pre-dr-6a.txt
