split mesonlib into a package

Currently mesonlib does some import tricks to figure out whether it
needs to use windows or posix specific functions. This is a little
hacky, but works fine. However, the way the typing stubs are implemented
for the msvcrt and fnctl modules will cause mypy to fail on the other
platform, since the functions are not implemented.

To aleviate this (and for slightly cleaner design), I've split mesonlib
into a pacakge with three modules. A universal module contains all of
the platform agnositc code, a win32 module contains window specific
code, a posix module contains the posix specific code, and a platform
module contains no-op implementations. Then the package's __init__ file
imports all of the universal functions and all of the functions from the
approriate platform module, or the no-op versions as fallbacks. This
makes mypy happy, and avoids `if`ing all over the code to switch between
the platform specific code.

1 files changed, 2 insertions, 2 deletions

diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 1a7f3f1..219b0f2 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -867,7 +867,7 @@ class Environment:
         # re-initialized with project options by the interpreter during
         # build file parsing.
         # meson_command is used by the regenchecker script, which runs meson
-        self.coredata = coredata.CoreData(options, self.scratch_dir, mesonlib.meson_command)
+        self.coredata = coredata.CoreData(options, self.scratch_dir, mesonlib.get_meson_command())
         self.first_invocation = True
 
     def is_cross_build(self, when_building_for: MachineChoice = MachineChoice.HOST) -> bool:
@@ -887,7 +887,7 @@ class Environment:
         return self.coredata
 
     def get_build_command(self, unbuffered=False):
-        cmd = mesonlib.meson_command[:]
+        cmd = mesonlib.get_meson_command().copy()
         if unbuffered and 'python' in os.path.basename(cmd[0]):
             cmd.insert(1, '-u')
         return cmd