MSYS2 Mingw-w64 cmake failed

following the README
in the part of Building. cmake says "System is unknown, create Platform/MINGW_NT-10.0..." and "Checking for module 'gtk+-3.0'"

[andlabs]

Very strange; I think the warning at the top of the output there has something to do with it (CMake is thinking this is Unix and not Windows).

[andlabs]

Can you try with meson in the current head?

[rubyFeedback]

[This can probably be closed as the user account is no longer there. Hopefully meson fixed
these issues.]

[bcampbell]

Just leaving some breadcrumbs in case someone else has this problem...

I think it depends on which version of cmake you have installed - the msys2 version, or the windows build from the cmake website.
I forget the details, but I think they make different default assumptions about various things, like which compiler to use and how to scan for dependencies.
Hopefully a moot point now the switch has been made to meson!