bpo-40910: Export Py_GetArgcArgv() function (GH-20721)

Export explicitly the Py_GetArgcArgv() function to the C API and
document the function. Previously, it was exported implicitly which
no longer works since Python is built with -fvisibility=hidden.

* Add PyConfig._orig_argv member.
* Py_InitializeFromConfig() no longer calls _PyConfig_Write() twice.
* PyConfig_Read() no longer initializes Py_GetArgcArgv(): it is now
  _PyConfig_Write() responsibility.
* _PyConfig_Write() result type becomes PyStatus instead of void.
* Write an unit test on Py_GetArgcArgv().

1 files changed, 9 insertions, 0 deletions

diff --git a/Doc/c-api/init_config.rst b/Doc/c-api/init_config.rst
index 7b8e894..c51b157 100644
--- a/Doc/c-api/init_config.rst
+++ b/Doc/c-api/init_config.rst
@@ -43,6 +43,7 @@ Functions:
 * :c:func:`Py_PreInitializeFromArgs`
 * :c:func:`Py_PreInitializeFromBytesArgs`
 * :c:func:`Py_RunMain`
+* :c:func:`Py_GetArgcArgv`
 
 The preconfiguration (``PyPreConfig`` type) is stored in
 ``_PyRuntime.preconfig`` and the configuration (``PyConfig`` type) is stored in
@@ -984,6 +985,14 @@ customized Python always running in isolated mode using
 :c:func:`Py_RunMain`.
 
 
+Py_GetArgcArgv()
+----------------
+
+.. c:function:: void Py_GetArgcArgv(int *argc, wchar_t ***argv)
+
+   Get the original command line arguments, before Python modified them.
+
+
 Multi-Phase Initialization Private Provisional API
 --------------------------------------------------