Re: [PATCH] Use __fpurge when fpurge is undeclared

["Jun. T" <takimoto-j@xxxxxxxxxxxxxxxxx>]

In the thread (28 and 29, Jan 2024)
'[PATCH] Improve stdio management when redirecting descriptors'

> 2024/01/29 22:03, Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
> 
> On Mon, Jan 29, 2024 at 2:59 AM Mikael Magnusson <mikachu@xxxxxxxxx> wrote:
>> 
>> According to my manpages, int fpurge is not available on linux
>> (glibc), but there is void __fpurge.
> 
> Yes, however, as far as we can tell stdio implementations that don't
> expose fpurge don't need to call it.

So the first thing we need to know is whether calling fpurge() is necessary
or not on musl-based systems.

On your Gentoo, without your patch, please try the following:

% ./configre
then comment out the line
#define HAVE_FPURGE 1
in config.h, and
% make
% TESTNUM=A05 make check

Does this test succeed?

On macOS and FreeBSD, where fpurge() is available, the above test fails
at the test hunk

  print foo >&-
0:'>&-' redirection

so it seems calling fpurge() is indeed necessary on these systems.

If the test succeeds without calling fpurge() on Gentoo, I _guess_
fpurge() is not required, but not 100% sure.