Support using pypiwin32 or pywin32-ctypes

pypiwin32 doesn't work on msys2 for a variety of reasons, but pywin32-ctypes
supports the minimum API that pyinstaller needs

See also: https://github.com/Alexpux/MINGW-packages/issues/751

PyInstaller/compat.py

@@ -846,8 +846,17 @@ def check_requirements():
     if is_win:
         try:
             from PyInstaller.utils.win32 import winutils
-            pywintypes = winutils.import_pywin32_module('pywintypes')
+            try:
+                pywintypes = winutils.import_pywin32_module('pywintypes')
+            except ImportError:
+                from win32ctypes.pywin32 import pywintypes
+                from win32ctypes.pywin32 import win32api
+
+                # if this succeeded, then install pywin32-ctypes into sys.modules
+                sys.modules['win32api'] = win32api
+                sys.modules['pywintypes'] = pywintypes
+
         except ImportError:
             raise SystemExit('PyInstaller cannot check for assembly dependencies.\n'
-                             'Please install PyWin32.\n\n'
+                             'Please install PyWin32 or pywin32-ctypes.\n\n'
                              'pip install pypiwin32\n')

PyInstaller/lib/modulegraph/find_modules.py

@@ -187,6 +187,7 @@ def plat_prepare(includes, packages, excludes):
             'nturl2path',
             'win32api',
             'win32con',
+            'win32ctypes',
             'win32event',
             'win32evtlogutil',
             'win32evtlog',

setup.py

@@ -29,9 +29,13 @@
     try:
         import pywintypes
     except ImportError:
-        # 'pypiwin32' is PyWin32 package made installable by 'pip install'
-        # command.
-        REQUIREMENTS.append('pypiwin32')
+        # try using pywin32-ctypes, as pypiwin32 doesn't compile for msys2
+        try:
+            import win32ctypes.pywin32.pywintypes
+        except ImportError:
+            # 'pypiwin32' is PyWin32 package made installable by 'pip install'
+            # command. Prefer it by default.
+            REQUIREMENTS.append('pypiwin32')
 
 
 # Create long description from README.rst and doc/CHANGES.rst.

tests/functional/scripts/pyi_win_py3_no_shortpathname.py

@@ -10,7 +10,12 @@
 # This script is used by multiple tests. It checks that various paths set by the
 # bootloader are usable filenames.
 
-import sys, os, win32api
+import sys, os
+
+try:
+    import win32api
+except ImportError:
+    from win32ctypes.pywin32 import win32api
 
 if sys.version_info[0] == 2:
     safe_repr = repr