bpo-36724: Add _PyWarnings_Fini() (#12963)

Py_FinalizeEx() now clears _PyRuntime.warnings variables and
_PyRuntime.exitfuncs.

Changes:

* Add _PyWarnings_Fini(): called by Py_FinalizeEx()
* call_ll_exitfuncs() now clears _PyRuntime.exitfuncs while iterating
  on it (on backward order).

1 files changed, 27 insertions, 16 deletions

diff --git a/Python/_warnings.c b/Python/_warnings.c
index 33b4615..388b299 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -1259,35 +1259,46 @@ _PyWarnings_Init(void)
     if (m == NULL)
         return NULL;
 
-    if (_PyRuntime.warnings.filters == NULL) {
-        _PyRuntime.warnings.filters = init_filters();
-        if (_PyRuntime.warnings.filters == NULL)
+    struct _warnings_runtime_state *state = &_PyRuntime.warnings;
+    if (state->filters == NULL) {
+        state->filters = init_filters();
+        if (state->filters == NULL)
             return NULL;
     }
-    Py_INCREF(_PyRuntime.warnings.filters);
-    if (PyModule_AddObject(m, "filters", _PyRuntime.warnings.filters) < 0)
+    Py_INCREF(state->filters);
+    if (PyModule_AddObject(m, "filters", state->filters) < 0)
         return NULL;
 
-    if (_PyRuntime.warnings.once_registry == NULL) {
-        _PyRuntime.warnings.once_registry = PyDict_New();
-        if (_PyRuntime.warnings.once_registry == NULL)
+    if (state->once_registry == NULL) {
+        state->once_registry = PyDict_New();
+        if (state->once_registry == NULL)
             return NULL;
     }
-    Py_INCREF(_PyRuntime.warnings.once_registry);
+    Py_INCREF(state->once_registry);
     if (PyModule_AddObject(m, "_onceregistry",
-                           _PyRuntime.warnings.once_registry) < 0)
+                           state->once_registry) < 0)
         return NULL;
 
-    if (_PyRuntime.warnings.default_action == NULL) {
-        _PyRuntime.warnings.default_action = PyUnicode_FromString("default");
-        if (_PyRuntime.warnings.default_action == NULL)
+    if (state->default_action == NULL) {
+        state->default_action = PyUnicode_FromString("default");
+        if (state->default_action == NULL)
             return NULL;
     }
-    Py_INCREF(_PyRuntime.warnings.default_action);
+    Py_INCREF(state->default_action);
     if (PyModule_AddObject(m, "_defaultaction",
-                           _PyRuntime.warnings.default_action) < 0)
+                           state->default_action) < 0)
         return NULL;
 
-    _PyRuntime.warnings.filters_version = 0;
+    state->filters_version = 0;
     return m;
 }
+
+
+void
+_PyWarnings_Fini(_PyRuntimeState *runtime)
+{
+    struct _warnings_runtime_state *state = &runtime->warnings;
+    Py_CLEAR(state->filters);
+    Py_CLEAR(state->once_registry);
+    Py_CLEAR(state->default_action);
+}