[gtk-doc/win-no-msys: 7/8] WIP: Support MSVC compilers...

[Chun-wei Fan <fanchunwei src gnome org>]

commit d6cd374568fc44ca1cae9af9a518e52b3ada2c19
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Apr 15 12:03:53 2020 +0800

    WIP: Support MSVC compilers...

 gtkdoc-scangobj.in | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 gtkdoc/scangobj.py |  7 +++++-
 2 files changed, 78 insertions(+), 2 deletions(-)
---
diff --git a/gtkdoc-scangobj.in b/gtkdoc-scangobj.in
index 7660c70..5149e67 100755
--- a/gtkdoc-scangobj.in
+++ b/gtkdoc-scangobj.in
@@ -21,9 +21,15 @@
 #
 
 import argparse
+import distutils
 import os
 import sys
 
+from distutils import ccompiler
+from distutils.cygwinccompiler import Mingw32CCompiler
+from distutils.msvccompiler import MSVCCompiler
+from distutils.sysconfig import customize_compiler
+
 try:
   import gtkdoc_uninstalled
 except ModuleNotFoundError:
@@ -31,7 +37,69 @@ except ModuleNotFoundError:
 
 from gtkdoc import common, config, scangobj
 
+def check_is_msvc():
+    compiler = None
+    is_msvc = False
+    if os.name == 'nt':
+        # The compiler used here on Windows may well not be
+        # the same compiler that was used to build Python,
+        # as the official Python binaries are built with
+        # Visual Studio
+        compiler_name = os.environ.get('CC')
+        if compiler_name is None:
+            if os.environ.get('MSYSTEM') == 'MINGW32' or os.environ.get('MSYSTEM') == 'MINGW64':
+                compiler_name = 'mingw32'
+            else:
+                compiler_name = distutils.ccompiler.get_default_compiler()
+
+        if compiler_name != 'msvc' and \
+           compiler_name != 'mingw32' and \
+           compiler_name != 'clang' and \
+           compiler_name != 'clang-cl':
+            raise SystemExit('Specified Compiler \'%s\' is unsupported.' % compiler_name)
+    else:
+        # XXX: Is it common practice to use a non-Unix compiler
+        #      class instance on non-Windows on platforms g-i supports?
+        compiler_name = distutils.ccompiler.get_default_compiler()
+
+    # Now, create the distutils ccompiler instance based on the info we have.
+    if compiler_name == 'msvc':
+        # For MSVC, we need to create a instance of a subclass of distutil's
+        # MSVC9Compiler class, as it does not provide a preprocess()
+        # implementation
+        compiler = distutils.msvccompiler.MSVCCompiler()
+    else:
+        compiler = distutils.ccompiler.new_compiler(compiler=compiler_name)
+        customize_compiler(compiler)
+
+    # customize_compiler() from distutils only does customization
+    # for 'unix' compiler type.  Also, avoid linking to msvcrxx.dll
+    # for MinGW builds as the dumper binary does not link to the
+    # Python DLL, but link to msvcrt.dll if necessary.
+    if isinstance(compiler, Mingw32CCompiler):
+        if compiler.dll_libraries != ['msvcrt']:
+            self.compiler.dll_libraries = []
+#        if self.compiler.preprocessor is None:
+#            self.compiler.preprocessor = self.compiler.compiler + ['-E']
+
+    if isinstance(compiler, distutils.msvccompiler.MSVCCompiler):
+    # We trick distutils to believe that we are (always) using a
+    # compiler supplied by a Windows SDK, so that we avoid launching
+    # a new build environment to detect the compiler that is used to
+    # build Python itself, which is not desirable, so that we use the
+    # compiler commands (and env) as-is.
+        os.environ['DISTUTILS_USE_SDK'] = '1'
+        if 'MSSdk' not in os.environ:
+            if 'WindowsSDKDir' in os.environ:
+                os.environ['MSSdk'] = os.environ.get('WindowsSDKDir')
+            elif os.environ.get('VCInstallDir'):
+                os.environ['MSSdk'] = os.environ.get('VCInstallDir')
+        is_msvc = True
+
+    return is_msvc
+
 if __name__ == '__main__':
+    is_msvc = check_is_msvc()
     parser = argparse.ArgumentParser(
         description='gtkdoc-rebase version %s - introspect g-objects' % config.version)
     parser.add_argument('--version', action='version', version=config.version)
@@ -66,7 +134,10 @@ if __name__ == '__main__':
         options.ldflags = ' '.join(options.ldflags)
 
     if not options.cc:
-        options.cc = os.environ.get('CC', 'gcc')
+        if is_msvc:
+            options.cc = os.environ.get('CC', 'cl')
+        else:
+            options.cc = os.environ.get('CC', 'gcc')
     if not options.ld:
         options.ld = os.environ.get('LD', options.cc)
     if not options.cflags:
diff --git a/gtkdoc/scangobj.py b/gtkdoc/scangobj.py
index 7434ec1..74145d4 100644
--- a/gtkdoc/scangobj.py
+++ b/gtkdoc/scangobj.py
@@ -1288,7 +1288,12 @@ def run(options):
     if 'libtool' in options.cc:
         o_file = options.module + '-scan.lo'
     else:
-        o_file = options.module + '-scan.o'
+        obj_ext = None
+        if options.cc == 'cl':
+            obj_ext = '.obj'
+        else:
+            obj_ext = '.o'
+        o_file = options.module + '-scan' + obj_ext
 
     x_file = options.module + '-scan' + config.exeext