Conan-center-index: [question] Managing MSYS build require outside of the recipes

[danimtb]

Coming from https://github.com/conan-io/conan-center-index/pull/971#discussion_r384523076

To enable proper MinGW support in some of the recipes, we are repeating every time the code

def build_requirements(self):
    if tools.os_info.is_windows and "CONAN_BASH_PATH" not in os.environ and \
        tools.os_info.detect_windows_subsystem() != "msys2":
            self.build_requires("msys2/20190524")

I personally understand that it is very convenient to have the build require there, but this is clearly a pattern in all the recipes that enable support for MinGW.

My question is: Should we stop adding this code in the recipes and recommend people using the msys package in their mingw profiles as the cannonical way to create the packages?

I think having msys together with mingw should be a well-known pratice for all of those that are these creating packages

cc/ @SSE4 @uilianries @madebr

[madebr]

No, the build requirement must be there.

It is often present for MSVC builds if there is only a autotools build system.

[madebr]

What I do not know is why we add tools.os_info.detect_windows_subsystem() != "msys2":.
Most often, I think it does not matter what subsystem is used.

I think the following would also be fine:

def build_requirements(self):
    if tools.os_info.is_windows and "CONAN_BASH_PATH" not in os.environ and \
        not tools.os_info.detect_windows_subsystem():
            self.build_requires("msys2/20190524")

But granted, most of us build and test using the msys2 subsystem.

[danimtb]

Ok, now I understand better.

Regarding the tools.os_info.detect_windows_subsystem() != "msys2", maybe @ericLemanissier can help us with this

[ericLemanissier]

Some projects explicitly mention cygwin (or msys2). Accepting all subsystem means we have to at least do a test on several subsystems, and this have to be done on a case by case basis. Replacing tools.os_info.detect_windows_subsystem() != "msys2" with not tools.os_info.detect_windows_subsystem() is not a major simplification anyway

[madebr]

@ericLemanissier I agree. Thanks for the clarification!

[danimtb]

Thanks a lot for the feedback guys!