bpo-36763: Add _PyCoreConfig_InitPythonConfig() (GH-13388)

Add new functions to get the Python interpreter behavior:

* _PyPreConfig_InitPythonConfig()
* _PyCoreConfig_InitPythonConfig()

Add new functions to get an isolated configuration:

* _PyPreConfig_InitIsolatedConfig()
* _PyCoreConfig_InitIsolatedConfig()

Replace _PyPreConfig_INIT and _PyCoreConfig_INIT with new functions
_PyPreConfig_Init() and _PyCoreConfig_Init().

_PyCoreConfig: set configure_c_stdio and parse_argv to 0 by default
to behave as Python 3.6 in the default configuration.

_PyCoreConfig_Read() no longer sets coerce_c_locale_warn to 1 if it's
equal to 0. coerce_c_locale_warn must now be set to -1 (ex: using
_PyCoreConfig_InitPythonConfig()) to enable C locale coercion
warning.

Add unit tests for _PyCoreConfig_InitPythonConfig()
and _PyCoreConfig_InitIsolatedConfig().

Changes:

* Rename _PyCoreConfig_GetCoreConfig() to _PyPreConfig_GetCoreConfig()
* Fix core_read_precmdline(): handle parse_argv=0
* Fix _Py_PreInitializeFromCoreConfig(): pass coreconfig.argv
  to _Py_PreInitializeFromPyArgv(), except if parse_argv=0

1 files changed, 12 insertions, 7 deletions

diff --git a/Modules/main.c b/Modules/main.c
index bb103c28a3..72546a21ca 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -52,23 +52,28 @@ pymain_init(const _PyArgv *args)
     fedisableexcept(FE_OVERFLOW);
 #endif
 
-    _PyPreConfig preconfig = _PyPreConfig_INIT;
-    /* Set to -1 to enable them depending on the LC_CTYPE locale and the
-       environment variables (PYTHONUTF8 and PYTHONCOERCECLOCALE)  */
-    preconfig.coerce_c_locale = -1;
-    preconfig.utf8_mode = -1;
+    _PyPreConfig preconfig;
+    _PyPreConfig_InitPythonConfig(&preconfig);
     err = _Py_PreInitializeFromPyArgv(&preconfig, args);
     if (_Py_INIT_FAILED(err)) {
         return err;
     }
 
+    _PyCoreConfig config;
+    err = _PyCoreConfig_InitPythonConfig(&config);
+    if (_Py_INIT_FAILED(err)) {
+        return err;
+    }
+
     /* pass NULL as the config: config is read from command line arguments,
        environment variables, configuration files */
     if (args->use_bytes_argv) {
-        return _Py_InitializeFromArgs(NULL, args->argc, args->bytes_argv);
+        return _Py_InitializeFromArgs(&config,
+                                      args->argc, args->bytes_argv);
     }
     else {
-        return _Py_InitializeFromWideArgs(NULL, args->argc, args->wchar_argv);
+        return _Py_InitializeFromWideArgs(&config,
+                                          args->argc, args->wchar_argv);
     }
 }