Improves test_underpth_nosite_file to reveal why it fails. (#1763)

* Improves test_underpth_nosite_file to reveal why it fails.

* Enable building with Windows 10 SDK.

* Fix WinSDK detection

* Fix initialization on Windows when a ._pth file exists.

* Fix tabs

* Adds comment about Py_GetPath call.

Author: zooba

Lib/test/test_site.py

@@ -547,12 +547,16 @@ def test_underpth_nosite_file(self):
         env = os.environ.copy()
         env['PYTHONPATH'] = 'from-env'
         env['PATH'] = '{};{}'.format(exe_prefix, os.getenv('PATH'))
-        rc = subprocess.call([exe_file, '-c',
-            'import sys; sys.exit(sys.flags.no_site and '
-            'len(sys.path) > 200 and '
-            'sys.path == %r)' % sys_path,
-            ], env=env)
-        self.assertTrue(rc, "sys.path is incorrect")
+        output = subprocess.check_output([exe_file, '-c',
+            'import sys; print("\\n".join(sys.path) if sys.flags.no_site else "")'
+        ], env=env, encoding='ansi')
+        actual_sys_path = output.rstrip().split('\n')
+        self.assert_(actual_sys_path, "sys.flags.no_site was False")
+        self.assertEqual(
+            actual_sys_path,
+            sys_path,
+            "sys.path is incorrect"
+        )
 
     def test_underpth_file(self):
         libpath = os.path.dirname(os.path.dirname(encodings.__file__))

PCbuild/python.props

@@ -63,6 +63,21 @@
     <PythonExe Condition="'$(PythonExe)' == ''">$(BuildPath)python$(PyDebugExt).exe</PythonExe>
   </PropertyGroup>
 
+  <PropertyGroup Condition="$(DefaultWindowsSDKVersion) == ''">
+    <!--
+    Attempt to select the latest installed WinSDK. If we don't find any, then we will
+    let the MSBuild targets determine which one it wants to use (typically the earliest
+    possible version). Since we limit WINVER to Windows 7 anyway, it doesn't really
+    matter which WinSDK version we use.
+    -->
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.15063'">10.0.15063.0</DefaultWindowsSDKVersion>
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.15063'">10.0.15063.0</DefaultWindowsSDKVersion>
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.10586'">10.0.10586.0</DefaultWindowsSDKVersion>
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.10586'">10.0.10586.0</DefaultWindowsSDKVersion>
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.10240'">10.0.10240.0</DefaultWindowsSDKVersion>
+    <DefaultWindowsSDKVersion Condition="$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Microsoft SDKs\Windows\v10.0@ProductVersion) == '10.0.10240'">10.0.10240.0</DefaultWindowsSDKVersion>
+  </PropertyGroup>
+  
   <PropertyGroup Condition="'$(OverrideVersion)' == ''">
     <!--
     Read version information from Include\patchlevel.h. The following properties are set:

Python/pylifecycle.c

@@ -412,10 +412,15 @@ _Py_InitializeEx_Private(int install_sigs, int install_importlib)
     if (interp->sysdict == NULL)
         Py_FatalError("Py_Initialize: can't initialize sys dict");
     Py_INCREF(interp->sysdict);
+
+    /* GetPath may initialize state that _PySys_EndInit locks
+       in, and so has to be called first.
+       
+       Hopefully one day Eric Snow will fix this. */
+    PySys_SetPath(Py_GetPath());
     if (_PySys_EndInit(interp->sysdict) < 0)
         Py_FatalError("Py_Initialize: can't initialize sys");
     _PyImport_FixupBuiltin(sysmod, "sys");
-    PySys_SetPath(Py_GetPath());
     PyDict_SetItemString(interp->sysdict, "modules",
                          interp->modules);