bpo-34523: Add _PyCoreConfig.filesystem_encoding (GH-8963)

_PyCoreConfig_Read() is now responsible to choose the filesystem
encoding and error handler. Using Py_Main(), the encoding is now
chosen even before calling Py_Initialize().

_PyCoreConfig.filesystem_encoding is now the reference, instead of
Py_FileSystemDefaultEncoding, for the Python filesystem encoding.

Changes:

* Add filesystem_encoding and filesystem_errors to _PyCoreConfig
* _PyCoreConfig_Read() now reads the locale encoding for the file
  system encoding.
* PyUnicode_EncodeFSDefault() and PyUnicode_DecodeFSDefaultAndSize()
  now use the interpreter configuration rather than
  Py_FileSystemDefaultEncoding and Py_FileSystemDefaultEncodeErrors
  global configuration variables.
* Add _Py_SetFileSystemEncoding() and _Py_ClearFileSystemEncoding()
  private functions to only modify Py_FileSystemDefaultEncoding and
  Py_FileSystemDefaultEncodeErrors in coreconfig.c.
* _Py_CoerceLegacyLocale() now takes an int rather than
  _PyCoreConfig for the warning.

1 files changed, 10 insertions, 0 deletions

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index f3dd3bb..b90366d 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -861,6 +861,16 @@ class SysModuleTest(unittest.TestCase):
     def test_no_duplicates_in_meta_path(self):
         self.assertEqual(len(sys.meta_path), len(set(sys.meta_path)))
 
+    @unittest.skipUnless(hasattr(sys, "_enablelegacywindowsfsencoding"),
+                         'needs sys._enablelegacywindowsfsencoding()')
+    def test__enablelegacywindowsfsencoding(self):
+        code = ('import sys',
+                'sys._enablelegacywindowsfsencoding()',
+                'print(sys.getfilesystemencoding(), sys.getfilesystemencodeerrors())')
+        rc, out, err = assert_python_ok('-c', '; '.join(code))
+        out = out.decode('ascii', 'replace').rstrip()
+        self.assertEqual(out, 'mbcs replace')
+
 
 @test.support.cpython_only
 class SizeofTest(unittest.TestCase):