bpo-36737: Use the module state C-API for warnings. (gh-13159)

Author: ericsnowcurrently

Include/internal/pycore_pylifecycle.h

@@ -81,7 +81,7 @@ extern void PyLong_Fini(void);
 extern void _PyFaulthandler_Fini(void);
 extern void _PyHash_Fini(void);
 extern int _PyTraceMalloc_Fini(void);
-extern void _PyWarnings_Fini(_PyRuntimeState *runtime);
+extern void _PyWarnings_Fini(PyInterpreterState *interp);
 
 extern void _PyGILState_Init(
     _PyRuntimeState *runtime,

Include/internal/pycore_pystate.h

@@ -90,6 +90,8 @@ struct _is {
     PyObject *pyexitmodule;
 
     uint64_t tstate_next_unique_id;
+
+    struct _warnings_runtime_state warnings;
 };
 
 PyAPI_FUNC(struct _is*) _PyInterpreterState_LookUpID(PY_INT64_T);
@@ -179,7 +181,6 @@ typedef struct pyruntimestate {
     int nexitfuncs;
 
     struct _gc_runtime_state gc;
-    struct _warnings_runtime_state warnings;
     struct _ceval_runtime_state ceval;
     struct _gilstate_runtime_state gilstate;
 

Misc/NEWS.d/next/Core and Builtins/2019-05-07-12-18-11.bpo-36737.XAo6LY.rst

@@ -0,0 +1,2 @@
+Move PyRuntimeState.warnings into per-interpreter state (via "module
+state").