gh-123853: Cleanup Windows 95 locale fallback support

Lib/locale.py

@@ -557,6 +557,8 @@ def getdefaultlocale(envvars=('LC_ALL', 'LC_CTYPE', 'LANG', 'LANGUAGE')):
         1766.  code and encoding can be None in case the values cannot
         be determined.
 
+        On Windows, raise a `WindowsError` if retrieving the locale fails.
+
     """
 
     return _getdefaultlocale(envvars)
@@ -569,12 +571,11 @@ def _getdefaultlocale(envvars=('LC_ALL', 'LC_CTYPE', 'LANG', 'LANGUAGE')):
         code, encoding = _locale._getdefaultlocale()
     except (ImportError, AttributeError):
         pass
+    except OSError as e:
+        if sys.platform == "win32" and isinstance(e, WindowsError):
+            raise
     else:
-        # make sure the code/encoding values are valid
-        if sys.platform == "win32" and code and code[:2] == "0x":
-            # map windows language identifier to language name
-            code = windows_locale.get(int(code, 0))
-        # ...add other platform-specific processing here, if
+        # add other platform-specific processing here, if
         # necessary...
         return code, encoding
 

Misc/NEWS.d/next/Library/2026-02-21-17-34-53.gh-issue-123853.6RUwWh.rst

@@ -0,0 +1 @@
+Removed Windows 95 compatibility for :func:`locale.getdefaultlocale`.

Modules/_localemodule.c

@@ -555,20 +555,9 @@ _locale__getdefaultlocale_impl(PyObject *module)
             return Py_BuildValue("ss", locale, encoding);
     }
 
-    /* If we end up here, this windows version didn't know about
-       ISO639/ISO3166 names (it's probably Windows 95).  Return the
-       Windows language identifier instead (a hexadecimal number) */
-
-    locale[0] = '0';
-    locale[1] = 'x';
-    if (GetLocaleInfoA(LOCALE_USER_DEFAULT, LOCALE_IDEFAULTLANGUAGE,
-                      locale+2, sizeof(locale)-2)) {
-        return Py_BuildValue("ss", locale, encoding);
-    }
-
     /* cannot determine the language code (very unlikely) */
-    Py_INCREF(Py_None);
-    return Py_BuildValue("Os", Py_None, encoding);
+    /* if any of GetLocaleInfoA above failed */
+    return PyErr_SetFromWindowsErr(0);
 }
 #endif