fix int -> uint warning

[Acretock]

in my project i tried to mute warnings from fmt, but this one persist, should be harmless.

[vitaut]

Could you post the complete warning message and platform details?

[Acretock]

Could you post the complete warning message and platform details?

warnings, build with Android Studio on Windows10

warning: implicit conversion loses integer precision: 'int' to 'mode_t' (aka 'unsigned short') [-Wimplicit-int-conversion]
warning: implicit conversion changes signedness: 'int' to 'mode_t' (aka 'unsigned int') [-Wsign-conversion]

[vitaut]

This won't work on Windows where mode is int. The solution would be to use mode_t here and define it near the constants in https://github.com/fmtlib/fmt/blob/master/src/os.cc#L32-L43

[AlexGuteniev]

Wouldn't warning disappear if constexpr is used, so that the compiler will have to substitute the value and not being afraid of narrowing. Then it could be constexpr auto I guess.

[vitaut]

I don't think constexpr is relevant here and auto will just result in int. Note that the warning is not on this line.

[phprus]

For win32:

#ifndef __MINGW32__
using mode_t = int;
#endif

[phprus]

@vitaut , @Acretock

Mingw always defines the _mode_t type. And in addition, the mode_t type is defined (if the NO_OLDNAMES macro is not defined).

See:
https://github.com/mirror/mingw-w64/blob/19ecabd807e3429ecf88263107911958b63d4e76/mingw-w64-headers/crt/sys/types.h#L72-L79

Maybe define the type like this:

#ifdef _WIN32
#  ifdef __MINGW32__
using fmt_mode_t = _mode_t;
#  else
using fmt_mode_t = int;
#  endif
#else
using fmt_mode_t = mode_t;
#endif

And then use the fmt_mode_t type?

[vitaut]

Let's put mode_t in the fmt::detail namespace and in the file constructor add using namespace fmt::detail. Then it will pick up our fmt::detail::mode_t if available and the global one otherwise. Also no need to check for __MINGW32__.

[vitaut]

Thank you