Re: Remaining dependency on setlocale()

On Thu, 2025-07-10 at 11:53 +1200, Thomas Munro wrote:
> On Thu, Jul 10, 2025 at 10:52 AM Jeff Davis <pgsql(at)j-davis(dot)com>
> wrote:
> > The first problem -- how to affect the encoding of strings returned
> > by
> > strerror() on windows -- may be solvable as well. It looks like
> > LC_MESSAGES is not supported at all on windows, so the only thing
> > to be
> > concerned about is the encoding, which is affected by LC_CTYPE. But
> > windows doesn't offer uselocale() or strerror_l(). The only way
> > seems
> > to be to call _configthreadlocale(_ENABLE_PER_THREAD_LOCALE) and
> > then
> > setlocale(LC_CTYPE, datctype) right before strerror(), and switch
> > it
> > back to "C" right afterward. Comments welcome.
>
> FWIW there is an example of that in src/port/pg_localeconv_r.c.

OK, so it seems we have a path forward here:

1. Have a global_libc_locale that represents all of the categories, and
keep it up to date with GUC changes. On windows, it requires keeping
the textual locale names handy (e.g. copies of datcollate and
datctype), and building the special locale string and doing
_create_locale(LC_ALL, "LC_ABC=somelocale;LC_XYZ=otherlocale").

2. When there's no _l() variant of a function, like strerror_r(), wrap
with uselocale(). On windows, this means using the trick above with
_configthreadlocale(_ENABLE_PER_THREAD_LOCALE).

I don't have a great windows development environment, and it appears CI
and the buildfarm don't offer great coverage either. Can I ask for a
volunteer to do the windows side of this work?

Regards,
Jeff Davis