Fix warning in clog.c about ignoring return value of ‘write’

[WilliamTambellini]

Dozens of warnings in clog.c:

[  2%] Linking CXX shared library libonnxruntime_providers_shared.so
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c:112:4: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
    write(STDERR_FILENO, out_buffer, prefix_chars + format_chars + CLOG_SUFFIX_LENGTH);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c: In function ‘clog_vlog_error’:
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c:188:4: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
    write(STDERR_FILENO, out_buffer, prefix_chars + format_chars + CLOG_SUFFIX_LENGTH);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c: In function ‘clog_vlog_warning’:
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c:264:4: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
    write(STDERR_FILENO, out_buffer, prefix_chars + format_chars + CLOG_SUFFIX_LENGTH);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c: In function ‘clog_vlog_info’:
/home/wtambellini/repos/onnxruntime/cmake/external/pytorch_cpuinfo/deps/clog/src/clog.c:340:4: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
    write(STDOUT_FILENO, out_buffer, prefix_chars + format_chars + CLOG_SUFFIX_LENGTH);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
....

line 112 https://github.com/pytorch/cpuinfo/blob/728f3e909fa5c57e0123c4658e234f6b1941385d/deps/clog/src/clog.c#L112

write() indeed returns a size_t : https://linux.die.net/man/2/write Would you mind if I add a check ? eg:

ssize_t rv =  write(STDOUT_FILENO, out_buffer, prefix_chars + format_chars + CLOG_SUFFIX_LENGTH);
asert(rv != -1);

[Maratyszcza]

It would be good to suppress the warning, but assert is not the right way to do it. assert may crash the whole program because of failed logging write.

[WilliamTambellini]

Hi @Maratyszcza
Sure, what about logging (warning ?error ?) if the rv == -1 ?

[Maratyszcza]

rv == -1 indicates that we've had an error during logging. I don't expect anything good attempting to log the error about the logging error. The best option IMO is to ignore the error, and silence the compiler warning about it.

[WilliamTambellini]

Well, totally ignoring write() errors would make debugging even harder but nevermind. So would you accept a PR if I add target_compile_options(... "-Wno-unused-result") to the main CMakeList.txt, only for gcc builds ?

[Maratyszcza]

Fixed in #129