bpo-34485: Fix _Py_InitializeCore() for C locale coercion (GH-8979)

* _Py_InitializeCore() now sets the LC_CTYPE locale to the user
  preferred locale before checking if the C locale should be coerced
  or not in _PyCoreConfig_Read().
* Fix pymain_read_conf(): remember if the C locale has been coerced
  when the configuration should be read again if the encoding has
  changed.

1 files changed, 6 insertions, 4 deletions

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 29711dfc98..4d248ede9c 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -659,10 +659,6 @@ _Py_InitializeCore_impl(PyInterpreterState **interp_p,
     _PyRuntime.finalizing = NULL;
 
 #ifndef MS_WINDOWS
-    /* Set up the LC_CTYPE locale, so we can obtain
-       the locale's charset without having to switch
-       locales. */
-    _Py_SetLocaleFromEnv(LC_CTYPE);
     _emit_stderr_warning_for_legacy_locale(core_config);
 #endif
 
@@ -815,6 +811,12 @@ _Py_InitializeCore(PyInterpreterState **interp_p,
        (and the input configuration is read only). */
     _PyCoreConfig config = _PyCoreConfig_INIT;
 
+#ifndef MS_WINDOWS
+    /* Set up the LC_CTYPE locale, so we can obtain the locale's charset
+       without having to switch locales. */
+    _Py_SetLocaleFromEnv(LC_CTYPE);
+#endif
+
     _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
     if (_PyCoreConfig_Copy(&config, src_config) >= 0) {
         err = _PyCoreConfig_Read(&config);