Re: BUG #18940: PostgreSQL 18beta1 fails 'collate.windows.win1252' regression when building with MSYS/mingw

On Fri, May 30, 2025 at 7:42 AM PG Bug reporting form
<noreply@postgresql.org> wrote:
> The following bug has been logged on the website:
>
> Bug reference:      18940
> Logged by:          Joe Ayers
> Email address:      joseph.ayers@crunchydata.com
> PostgreSQL version: 18beta1
> Operating system:   Windows Server 2022
> Description:
>
> Hey there!
> In working on some test builds, PostgreSQL 18beta1 is failing the
> 'collate.windows.win1252' regression test due to missing locales. When
> building with MYS2/mingw (Tested Windows Server 2022 and Windows Server
> 2019), default locale that's pulled in is typically 'american_usa' as
> opposed to 'en_US', which causes the test to fail citing:
>     +ERROR:  could not create locale "en-US": No such file or directory
>     +DETAIL:  The operating system could not find any locale data for the
> locale name "en-US".
> The above error is repeated several times. Hoping to learn how to adjust the
> config to get this to pass, as the error did not occur for PG17 and below.
> Any info is appreciated.
> I can attach the full regression.diffs file for additional information if it
> would be of help.

Huh.  It passes on our CI:

https://cirrus-ci.com/task/4738549062303744

And on our build farm machine:

https://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=fairywren&br=master

I wonder what is different.  Are you using ucrt?  We started removing
bits and pieces related to the old msvcrt C runtime, but my
understanding is that msys2 compile should target ucrt by default.