[musl] setlocale() behaviour

[Alastair Houghton <ahoughton@apple.com>]

Hi there,

Presently, musl’s setlocale() function essentially always succeeds, even if it doesn’t actually have data for the requested locale. I note the previous message to the list in 2017

<https://www.openwall.com/lists/musl/2017/11/08/1>

discussing potential solutions, but unless I’m much mistaken nothing has really changed in the code?

This has come up because the test rig for libc++ tries to detect which locale data is installed so that it can run its own locale support tests (it’s trying to test the C++ locale support that it has constructed atop the C library’s underlying locale support).  If, for instance, you don’t have data for fr_FR installed, libc++ won’t run test cases that rely on that data.  On other C library implementations, that’s easy because setlocale() will return NULL in such a case, but musl doesn’t do that - instead, it sets up a copy of C.UTF-8, names it fr_FR and sets that as the current locale :-(

Kind regards,

Alastair.