[Bug libstdc++/127424] 27_io testsuite: opening a FIFO with O_RDWR is undefined in POSIX; 9964.cc also stopped testing PR 9964 in 2004

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127424

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Gökbey Keskin from comment #0)
> r0-56237-g6a734d618f8 (2004-02-04, "Correct flags to filebuf::open calls",
> the commit that introduced fopen_mode) changed both the mode and the
> expectation:
> 
>   -  filebuf* ret = fb.open(name, ios_base::out | ios_base::trunc);
>   +  filebuf* ret = fb.open(name, ios_base::in | ios_base::out);

For completeness, should we restore the ios_base::trunc as well? Your patch
doesn't do that.

Apart from that, this looks good, thanks.