Export reproc's status code constants in C++ binding

[HellsingDarge]

std::error_code (to which reproc++ maps in its methods) produces C++-defined error codes only for POSIX, making it impossible to check against them without using #if OS code

[DaanDeMeyer]

I don't understand. We simply store whatever error that was returned by the OS in the error code. All major standard library implementations define a mapping that allows comparing against these system specific errors using the generic constants from https://en.cppreference.com/w/cpp/error/errc.

If this doesn't work, please post a code example that reproduces the issue and I'll look into it

[HellsingDarge]

From the page you've linked:

The scoped enumeration std::errc defines the values of portable error conditions that correspond to the POSIX error codes.

On Windows (WAIT_TIMEOUT = 258L):

spdlog::info(std::errc::timed_out == std::error_code { 138, std::system_category() });              // false
spdlog::info(std::errc::timed_out == std::error_code {-REPROC_ETIMEDOUT, std::system_category() }); // false
spdlog::info(std::errc::timed_out == std::error_code { WAIT_TIMEOUT, std::system_category() });     // false

spdlog::info(std::errc::timed_out == std::error_code { 138, std::generic_category() });              // true
spdlog::info(std::errc::timed_out == std::error_code {-REPROC_ETIMEDOUT, std::generic_category() }); // false
spdlog::info(std::errc::timed_out == std::error_code { WAIT_TIMEOUT, std::generic_category() });     // false

spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code { 138, std::system_category() });              // false
spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code {-REPROC_ETIMEDOUT, std::system_category() }); // false
spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code { WAIT_TIMEOUT, std::system_category() });     // false

spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code { 138, std::generic_category() });              // true
spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code {-REPROC_ETIMEDOUT, std::generic_category() }); // false
spdlog::info(std::make_error_condition(std::errc::timed_out) == std::error_code { WAIT_TIMEOUT, std::generic_category() });     // false

[DaanDeMeyer]

I could have sworn MSVC's stdlib defined a mapping to allow comparing the system errors against the portable constants as well. I'll dig into the stdlib implementation when I find some time since it's been a while since I last looked at this.

[DaanDeMeyer]

I opened microsoft/STL#2572 against the STL. Let's see what they have to say.

[HellsingDarge]

I used timed_out as an example (since it's the one I've first encountered this problem on), so it may also affect other error codes

[DaanDeMeyer]

There's likely more indeed, but I'm starting with this one to see if they're receptive to modifying the mapping at all since technically changing this in the stdlib is a compat break so they might not want to change it. If that's the case we'll need to figure out something in reproc itself.

[DaanDeMeyer]

It seems they're interested in fixing this in stdlib but they don't do it in every release. If you encounter any more of these missing matches, I'd report them in that STL issue I linked so they can add extra matches for those as well.