ccompiler.py: Fix running on Visual Studio against SetupToolsfix-msvc-setuptools-distutils

...when we use the distutils that is packaged with SetupTools instead of the
one that comes with Python stdlib, which is often the case on newer Python 3.9+
(or so) installations.  Calling distutils.ccompiler.new_compiler() in this
case won't work when running on Visual Studio builds, and we use the
compiler instance for distutils's customize_compiler(), which was never
meant for Visual Studio.  So, we do nothing in customize_compiler() if we are
not using a unix compiler type.

This will fix the warn-* tests for G-I on Python 3.9.x or later when the default
distutils used is now the one that comes with setuptools, without needing to
use the envvar SETUPTOOLS_USE_DISTUTILS=stdlib.

1 files changed, 5 insertions, 7 deletions

diff --git a/giscanner/ccompiler.py b/giscanner/ccompiler.py
index 2912fe0e..7a8dee78 100644
--- a/giscanner/ccompiler.py
+++ b/giscanner/ccompiler.py
@@ -40,14 +40,12 @@ def customize_compiler(compiler):
     any macOS specific bits and which tries to avoid using any Python specific
     defaults if alternatives through env vars are given.
     """
-
-    # The original customize_compiler() in distutils calls into macOS setup
-    # code the first time it is called. This makes sure we run that setup
-    # code as well.
-    dummy = distutils.ccompiler.new_compiler()
-    orig_customize_compiler(dummy)
-
     if compiler.compiler_type == "unix":
+        # The original customize_compiler() in distutils calls into macOS setup
+        # code the first time it is called. This makes sure we run that setup
+        # code as well.
+        dummy = distutils.ccompiler.new_compiler()
+        orig_customize_compiler(dummy)
         (cc, cxx, ldshared, shlib_suffix, ar, ar_flags) = \
             get_config_vars('CC', 'CXX', 'LDSHARED', 'SHLIB_SUFFIX', 'AR', 'ARFLAGS')