[Bug libstdc++/110862] format out of bands read on format string "{0:{0}"

[gcc at pauldreik dot se via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110862

--- Comment #2 from Paul Dreik <gcc at pauldreik dot se> ---
(In reply to 康桓瑋 from comment #1)
> It does throw:
> 
> https://godbolt.org/z/5q3bb51YE

Sorry for being unclear. Yes, it throws but that is after the out of bounds
read has happened.