add 'vs' backend that automatically chooses between the vs backends

For newer VS versions, we can simply rely on 'VisualStudioVersion' being
set in the environment.
For VS2010, we fall back to check 'VSINSTALLDIR' for the version string.
If the backend can not be auto detected, we raise an exception to make the
user choose an explicit backend.
We also print the detected backend to the meson log.

1 files changed, 4 insertions, 0 deletions

diff --git a/mesonbuild/mesonmain.py b/mesonbuild/mesonmain.py
index 38c00a0..7db6310 100644
--- a/mesonbuild/mesonmain.py
+++ b/mesonbuild/mesonmain.py
@@ -145,6 +145,10 @@ If you want to change option values, use the mesonconf tool instead.'''
         if self.options.backend == 'ninja':
             from .backend import ninjabackend
             g = ninjabackend.NinjaBackend(b)
+        elif self.options.backend == 'vs':
+            from .backend import vs2010backend
+            g = vs2010backend.autodetect_vs_version(b)
+            mlog.log('Auto detected Visual Studio backend:', mlog.bold(g.name))
         elif self.options.backend == 'vs2010':
             from .backend import vs2010backend
             g = vs2010backend.Vs2010Backend(b)