Be stricter when detecting Windows/Cygwin

This removes the check for "mingw" for platform.system(). The only case I know
where "mingw" is return is if using a msys Python under a msys2 mingw environment.
This combination is not really supported by meson and will result in weird errors,
so remove the check.

The second change is checking sys.platform for cygwin instead of platform.system().
The former is document to return "cygwin", while the latter is not and just
returns uname().

While under Cygwin it uname() always starts with "cygwin" it's not hardcoded in MSYS2
and starts with the environment name. Using sys.platform is safer here.

Fixes #7552

1 files changed, 2 insertions, 2 deletions

diff --git a/mesonbuild/envconfig.py b/mesonbuild/envconfig.py
index 9402d38de..5258fa077 100644
--- a/mesonbuild/envconfig.py
+++ b/mesonbuild/envconfig.py
@@ -211,13 +211,13 @@ class MachineInfo:
         """
         Machine is windows?
         """
-        return self.system == 'windows' or 'mingw' in self.system
+        return self.system == 'windows'
 
     def is_cygwin(self) -> bool:
         """
         Machine is cygwin?
         """
-        return self.system.startswith('cygwin')
+        return self.system == 'cygwin'
 
     def is_linux(self) -> bool:
         """