Change user site-packages path to include the environment info

This should avoid mixing of user site-packages between python
from various environments. Previously, the user site-packages
should be located at `~/.local/lib/python3.10` for all environment
including 32-bits variants which caused problems with 64-bit trying to
load 32-bit extensions. Now this path will be changed to
`~/.local/lib/python3.10-<platform tag here>`, for example, in
CLANG64 this would be `~/.local/lib/python3.10-mingw_x86_64_clang`.

Fixes msys2-contrib#40

Lib/site.py

@@ -314,6 +314,26 @@ def joinuser(*args):
 
     return joinuser("~", ".local")
 
+# Copy of sysconfig.get_platform() but only for MinGW
+def _get_platform():
+    if os.name == 'nt':
+        if 'gcc' in sys.version.lower():
+            if 'ucrt' in sys.version.lower():
+                if 'amd64' in sys.version.lower():
+                    return 'mingw_x86_64_ucrt'
+                return 'mingw_i686_ucrt'
+            if 'clang' in sys.version.lower():
+                if 'amd64' in sys.version.lower():
+                    return 'mingw_x86_64_clang'
+                if 'arm64' in sys.version.lower():
+                    return 'mingw_aarch64'
+                if 'arm' in sys.version.lower():
+                    return 'mingw_armv7'
+                return 'mingw_i686_clang'
+            if 'amd64' in sys.version.lower():
+                return 'mingw_x86_64'
+            return 'mingw_i686'
+    return sys.platform
 
 # Same to sysconfig.get_path('purelib', os.name+'_user')
 def _get_path(userbase):
@@ -325,9 +345,11 @@ def _get_path(userbase):
 
     implementation = _get_implementation()
     implementation_lower = implementation.lower()
-    if os.name == 'nt' and not _POSIX_BUILD:
-        ver_nodot = sys.winver.replace('.', '')
-        return f'{userbase}\\{implementation}{ver_nodot}\\site-packages'
+    if os.name == 'nt':
+        if not _POSIX_BUILD:
+            ver_nodot = sys.winver.replace('.', '')
+            return f'{userbase}\\{implementation}{ver_nodot}\\site-packages'
+        return f'{userbase}/lib/{implementation_lower}{version[0]}.{version[1]}-{_get_platform()}{abi_thread}/site-packages'
 
     if sys.platform == 'darwin' and sys._framework:
         return f'{userbase}/lib/{implementation_lower}/site-packages'

Lib/sysconfig/__init__.py

@@ -144,20 +144,20 @@ def joinuser(*args):
     _INSTALL_SCHEMES |= {
         # NOTE: When modifying "purelib" scheme, update site._get_path() too.
         'nt_user': {
-            'stdlib': '{userbase}/lib/{implementation}{py_version_short}{abi_thread}',
-            'platstdlib': '{userbase}/lib/{implementation}{py_version_short}{abi_thread}',
-            'purelib': '{userbase}/lib/{implementation}{py_version_short}{abi_thread}/site-packages',
-            'platlib': '{userbase}/lib/{implementation}{py_version_short}{abi_thread}/site-packages',
-            'include': '{userbase}/include/{implementation}{py_version_short}{abi_thread}',
+            'stdlib': '{userbase}/lib/{implementation}{py_version_short_plat}{abi_thread}',
+            'platstdlib': '{userbase}/lib/{implementation}{py_version_short_plat}{abi_thread}',
+            'purelib': '{userbase}/lib/{implementation}{py_version_short_plat}{abi_thread}/site-packages',
+            'platlib': '{userbase}/lib/{implementation}{py_version_short_plat}{abi_thread}/site-packages',
+            'include': '{userbase}/include/{implementation}{py_version_short_plat}{abi_thread}',
             'scripts': '{userbase}/bin',
             'data': '{userbase}',
             },
         'posix_user': {
-            'stdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
-            'platstdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
-            'purelib': '{userbase}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
-            'platlib': '{userbase}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
-            'include': '{userbase}/include/{implementation_lower}{py_version_short}{abi_thread}',
+            'stdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short_plat}{abi_thread}',
+            'platstdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short_plat}{abi_thread}',
+            'purelib': '{userbase}/lib/{implementation_lower}{py_version_short_plat}{abi_thread}/site-packages',
+            'platlib': '{userbase}/lib/{implementation_lower}{py_version_short_plat}{abi_thread}/site-packages',
+            'include': '{userbase}/include/{implementation_lower}{py_version_short_plat}{abi_thread}',
             'scripts': '{userbase}/bin',
             'data': '{userbase}',
             },
@@ -493,6 +493,10 @@ def _init_config_vars():
         _CONFIG_VARS['py_version_nodot_plat'] = sys.winver.replace('.', '')
     except AttributeError:
         _CONFIG_VARS['py_version_nodot_plat'] = ''
+    if os.name == 'nt' and _POSIX_BUILD:
+        _CONFIG_VARS['py_version_short_plat'] = f'{_PY_VERSION_SHORT}-{get_platform()}'
+    else:
+        _CONFIG_VARS['py_version_short_plat'] = _PY_VERSION_SHORT
 
     if os.name == 'nt' and not _POSIX_BUILD:
         _init_non_posix(_CONFIG_VARS)
@@ -583,7 +587,7 @@ def get_config_var(name):
     """
     return get_config_vars().get(name)
 
-
+# make sure to change site._get_platform() while changing this function
 def get_platform():
     """Return a string that identifies the current platform.