[Bug libstdc++/110974] format out of bounds read on invalid format string "{:{}."

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110974

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to CVS Commits from comment #3)
>             * include/std/format (_Spec::_S_parse_width_or_precision): Check
>             for empty range before dereferencing iterator.

Oops, I fixed it in _M_parse_precision instead, but forgot to change the commit
msg.