bpo-35081: Add _PyThreadState_GET() internal macro (GH-10266)

If Py_BUILD_CORE is defined, the PyThreadState_GET() macro access
_PyRuntime which comes from the internal pycore_state.h header.
Public headers must not require internal headers.

Move PyThreadState_GET() and _PyInterpreterState_GET_UNSAFE() from
Include/pystate.h to Include/internal/pycore_state.h, and rename
PyThreadState_GET() to _PyThreadState_GET() there.

The PyThreadState_GET() macro of pystate.h is now redefined when
pycore_state.h is included, to use the fast _PyThreadState_GET().

Changes:

* Add _PyThreadState_GET() macro
* Replace "PyThreadState_GET()->interp" with
  _PyInterpreterState_GET_UNSAFE()
* Replace PyThreadState_GET() with _PyThreadState_GET() in internal C
  files (compiled with Py_BUILD_CORE defined), but keep
  PyThreadState_GET() in the public header files.
* _testcapimodule.c: replace PyThreadState_GET() with
  PyThreadState_Get(); the module is not compiled with Py_BUILD_CORE
  defined.
* pycore_state.h now requires Py_BUILD_CORE to be defined.

1 files changed, 3 insertions, 3 deletions

diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 6971405..6da8b3a 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -174,7 +174,7 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
         return PYTHREAD_INVALID_THREAD_ID;
 #endif
 #if defined(THREAD_STACK_SIZE)
-    PyThreadState *tstate = PyThreadState_GET();
+    PyThreadState *tstate = _PyThreadState_GET();
     size_t stacksize = tstate ? tstate->interp->pythread_stacksize : 0;
     tss = (stacksize != 0) ? stacksize : THREAD_STACK_SIZE;
     if (tss != 0) {
@@ -591,7 +591,7 @@ _pythread_pthread_set_stacksize(size_t size)
 
     /* set to default */
     if (size == 0) {
-        PyThreadState_GET()->interp->pythread_stacksize = 0;
+        _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = 0;
         return 0;
     }
 
@@ -608,7 +608,7 @@ _pythread_pthread_set_stacksize(size_t size)
             rc = pthread_attr_setstacksize(&attrs, size);
             pthread_attr_destroy(&attrs);
             if (rc == 0) {
-                PyThreadState_GET()->interp->pythread_stacksize = size;
+                _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = size;
                 return 0;
             }
         }