[Bug libstdc++/42857] std::istream::ignore(std::streamsize n) calls unnecessary underflow

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42857

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Probably changed by one of the patches for PR 94749 or PR 96161, although I
still see two reads for the first example.