bpo-32030: Split Py_Main() into subfunctions (#4399)

* Don't use "Python runtime" anymore to parse command line options or
  to get environment variables: pymain_init() is now a strict
  separation.
* Use an error message rather than "crashing" directly with
  Py_FatalError(). Limit the number of calls to Py_FatalError(). It
  prepares the code to handle errors more nicely later.
* Warnings options (-W, PYTHONWARNINGS) and "XOptions" (-X) are now
  only added to the sys module once Python core is properly
  initialized.
* _PyMain is now the well identified owner of some important strings
  like: warnings options, XOptions, and the "program name". The
  program name string is now properly freed at exit.
  pymain_free() is now responsible to free the "command" string.
* Rename most methods in Modules/main.c to use a "pymain_" prefix to
  avoid conflits and ease debug.
* Replace _Py_CommandLineDetails_INIT with memset(0)
* Reorder a lot of code to fix the initialization ordering. For
  example, initializing standard streams now comes before parsing
  PYTHONWARNINGS.
* Py_Main() now handles errors when adding warnings options and
  XOptions.
* Add _PyMem_GetDefaultRawAllocator() private function.
* Cleanup _PyMem_Initialize(): remove useless global constants: move
  them into _PyMem_Initialize().
* Call _PyRuntime_Initialize() as soon as possible:
  _PyRuntime_Initialize() now returns an error message on failure.
* Add _PyInitError structure and following macros:

  * _Py_INIT_OK()
  * _Py_INIT_ERR(msg)
  * _Py_INIT_USER_ERR(msg): "user" error, don't abort() in that case
  * _Py_INIT_FAILED(err)

1 files changed, 9 insertions, 7 deletions

diff --git a/Python/pystate.c b/Python/pystate.c
index 55ff649..30f214e 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -35,7 +35,7 @@ to avoid the expense of doing their own locking).
 extern "C" {
 #endif
 
-void
+_PyInitError
 _PyRuntimeState_Init(_PyRuntimeState *runtime)
 {
     memset(runtime, 0, sizeof(*runtime));
@@ -46,17 +46,19 @@ _PyRuntimeState_Init(_PyRuntimeState *runtime)
     _PyEval_Initialize(&runtime->ceval);
 
     runtime->gilstate.check_enabled = 1;
+
     /* A TSS key must be initialized with Py_tss_NEEDS_INIT
        in accordance with the specification. */
-    {
-        Py_tss_t initial = Py_tss_NEEDS_INIT;
-        runtime->gilstate.autoTSSkey = initial;
-    }
+    Py_tss_t initial = Py_tss_NEEDS_INIT;
+    runtime->gilstate.autoTSSkey = initial;
 
     runtime->interpreters.mutex = PyThread_allocate_lock();
-    if (runtime->interpreters.mutex == NULL)
-        Py_FatalError("Can't initialize threads for interpreter");
+    if (runtime->interpreters.mutex == NULL) {
+        return _Py_INIT_ERR("Can't initialize threads for interpreter");
+    }
+
     runtime->interpreters.next_id = -1;
+    return _Py_INIT_OK();
 }
 
 void