compile issue on Cygwin

[phlptp]

I am getting a compile error on cygwin 3.3.3

/fmtlib/src/os.cc:207:27: error: ‘::fileno’ has not been declared; did you mean ‘file’?
  207 |   int fd = FMT_POSIX_CALL(fileno FMT_ARGS(file_));
      |                           ^~~~~~
fmtlib/include/fmt/os.h:58:36: note: in definition of macro ‘FMT_POSIX_CALL’
   58 | #    define FMT_POSIX_CALL(call) ::call
      |                                    ^~~~
fmtlib/src/os.cc: In member function ‘fmt::v8::buffered_file fmt::v8::file::fdopen(const char*)’:
fmtlib/src/os.cc:335:28: error: ‘::fdopen’ has not been declared; did you mean ‘fopen’?
  335 |   FILE* f = FMT_POSIX_CALL(fdopen(fd_, mode));
      |                            ^~~~~~
fmtlib/include/fmt/os.h:58:36: note: in definition of macro ‘FMT_POSIX_CALL’
   58 | #    define FMT_POSIX_CALL(call) ::call
      |                                    ^~~~

fmt is compiled as part of a CMake subproject. It compiles fine in other contexts including same compiler on different platforms.
C++17 gcc 11.2

This is Cygwin 64 bit with the latest release of fmt. Not sure if I should be supplying additional arguments or something else is going on here or where to look to fix it.

[vitaut]

I'm not sure why cygwin doesn't define fdopen (and fileno). If you have a workaround for this issue a PR would be welcome. You can disable this functionality via cmake -DFMT_OS=OFF ...

[vitaut]

According to https://stackoverflow.com/questions/15944051/error-fdopen-was-not-declared-found-with-g-4-that-compiled-with-g3 cygwin may disable POSIX APIs when compiling with -std=c++11 or similar. The solution is to use -std=gnu++11. Closing as this doesn't look like a bug in {fmt} but as mentioned earlier a PR with a workaround would be welcome.

[phlptp]

Thanks, I tried a few things as workarounds but nothing worked including using -std=gnu++17 and adding -D_POSIX_C_SOURCE=200809

The -DFMT_OS=OFF did work though, I figured there had to a flag that controlled some of that, so that was what I was missing.