python3: fix wrong path separator in module paths with MSYSTEM set

The importlib bootstrap code hardcodes the path separators to use
as well (os.path doesn't exist yet). Check for MSYSTEM there and
adjust the separators.

This makes things like module.__path__ use the same separator in all
places again and for example fixes pytest with MSYSTEM set.

Fixes #6035

mingw-w64-python3/3000-importlib-bootstrap-path-sep.patch

@@ -0,0 +1,14 @@
+--- Python-3.8.0/Lib/importlib/_bootstrap_external.py.orig	2019-12-21 14:31:23.806479400 +0100
++++ Python-3.8.0/Lib/importlib/_bootstrap_external.py	2019-12-21 14:34:37.093867400 +0100
+@@ -1603,6 +1603,11 @@
+                 continue
+     else:
+         raise ImportError('importlib requires posix or nt')
++
++    if 'MSYSTEM' in os_module.environ:
++        path_separators = path_separators[::-1]
++        path_sep = path_separators[0]
++
+     setattr(self_module, '_os', os_module)
+     setattr(self_module, 'path_sep', path_sep)
+     setattr(self_module, 'path_separators', ''.join(path_separators))

mingw-w64-python3/PKGBUILD

@@ -19,7 +19,7 @@ pkgname="${MINGW_PACKAGE_PREFIX}-${_realname}"
 conflicts=("${MINGW_PACKAGE_PREFIX}-python2<2.7.16-7")
 _pybasever=3.8
 pkgver=${_pybasever}.0
-pkgrel=2
+pkgrel=3
 pkgdesc="A high-level scripting language (mingw-w64)"
 arch=('any')
 license=('PSF')
@@ -130,6 +130,7 @@ source=("https://www.python.org/ftp/python/${pkgver%rc?}/Python-${pkgver}.tar.xz
         2060-pass-gen-profile-ldflags.patch
         2070-distutils-add-windmc-to-cygwinccompiler.patch
         2080-pkg-config-windows-must-link-ext-with-python-lib.patch
+        3000-importlib-bootstrap-path-sep.patch
         5000-warnings-fixes.patch
         smoketests.py)
 
@@ -298,7 +299,10 @@ prepare() {
   
   apply_patch_with_msg 2070-distutils-add-windmc-to-cygwinccompiler.patch
   apply_patch_with_msg 2080-pkg-config-windows-must-link-ext-with-python-lib.patch
-  
+
+  # https://github.com/msys2/MINGW-packages/issues/6035
+  apply_patch_with_msg 3000-importlib-bootstrap-path-sep.patch
+
   apply_patch_with_msg 5000-warnings-fixes.patch
 
   autoreconf -vfi
@@ -391,6 +395,9 @@ build() {
     "${_extra_config[@]}" \
     OPT=""
 
+  # We patch importlib which is embedded in C headers, so regenerate them
+  make regen-importlib
+
   make
 }
 
@@ -554,5 +561,6 @@ sha256sums=('b356244e13fb5491da890b35b13b2118c3122977c2cd825e3eb6e7d462030d84'
             '6f1a48380445406709ba5c6b4b9c6f0301ea645324feb429f3719dc29b8f28ff'
             'b2f4083ada35c18876edf38220d84ca757cf710bc5c2d80ee8b5083dc6c2609f'
             '487c92837717975ad6c63fe2a1f8e8c5c9e0554e96000102d83c82f4a77fd9bd'
+            'f6ecf2edc9468210111d77e396853af49cb8a43d9bc0d20212f88cf2bc33685d'
             '24151631c3e70306ae92ffb8fea38992a752cd0a76771a5e53445f56c2be1f00'
-            '821402ddaef92140c70041b007bcf15e1cd5fe0fdb9f4f612da868382cc24585')
+            '8b9f0ff6624d9e8e86112f711bd1d261e9ebca2e2a2e3c5d9d0b0f0c0a292421')

mingw-w64-python3/smoketests.py

@@ -39,6 +39,16 @@ class Tests(unittest.TestCase):
     def test_sep(self):
         self.assertEqual(os.sep, SEP)
 
+    def test_module_file_path(self):
+        import asyncio
+        import zlib
+        self.assertEqual(zlib.__file__, os.path.normpath(zlib.__file__))
+        self.assertEqual(asyncio.__file__, os.path.normpath(asyncio.__file__))
+
+    def test_importlib_frozen_path_sep(self):
+        import importlib._bootstrap_external
+        self.assertEqual(importlib._bootstrap_external.path_sep, SEP)
+
     def test_os_commonpath(self):
         self.assertEqual(
             os.path.commonpath(