libc++ put_time outputs in wrong language on OpenBSD 7.4

[seanm]

On OpenBSD 7.4 (newest) on x86_64 with its default / built-in clang:

$ clang++ --version
OpenBSD clang version 13.0.0
Target: amd64-unknown-openbsd7.4
Thread model: posix
InstalledDir: /usr/bin

This reduced C++ case:

#include <ctime>
#include <iomanip>
#include <iostream>

int main() {
  std::time_t t = std::time(nullptr);
  std::cout.imbue(std::locale("es_ES.UTF-8"));
  std::cout << std::put_time(std::localtime(&t), "%a");
}

When run on a Tuesday, gives "Tue". It should be outputting "mar", for Spanish "martes" (meaning Tuesday). That's what I get with macOS and FreeBSD.

Giving the output in the wrong language looks like a bug. It should either respect the locale or give an error (https://godbolt.org/z/KoW8YPqfc) when constructing an unsupported locale.

I don't know if this is a libc++ bug or an OpenBSD bug...

[ldionne]

I think this is extremely likely to be an OpenBSD bug, since the C++ localization library generally just forwards to the underlying OS localization functions. Can you reproduce on OpenBSD with the following pure C code?

#include <stdio.h>
#include <locale.h>
#include <time.h>
#include <wchar.h>

int main() {
  setlocale(LC_TIME, "es_ES.UTF-8");
  wchar_t str[100];
  time_t t = time(NULL);
  wcsftime(str, 100, L"%a", localtime(&t));
  wprintf(L"%ls\n", str);
}

I'll close this tentatively, but please reopen if the above code behaves correctly on OpenBSD but the corresponding C++ code doesn't.

[seanm]

Thanks @ldionne. You are correct, it occurs with that code too. I'll report to the OpenBSD folks.

[ischwarze]

This is not a bug in LLVM but intentional behaviour in the OpenBSD C library for security reasons and well documented on our locale(1), setlocale(3), wcsftime(3), and strftime(3) manual pages. Please close this ticket as invalid.

[vitaut]

Thanks for clarifying that this is intentional behavior in the C library implementation on OpenBSD but this brings a question whether relying on it in the C++ library is conforming. Perhaps libc++ should report an error when using intentionally disabled C locale functionality or use a different locale implementation on OpenBSD. Note that C++ locales are separate so pretty much nothing in locale(1), setlocale(3), wcsftime(3), and strftime(3) applies.