Add _PyThreadState_UncheckedGet()

Issue #26154: Add a new private _PyThreadState_UncheckedGet() function which
gets the current thread state, but don't call Py_FatalError() if it is NULL.

Python 3.5.1 removed the _PyThreadState_Current symbol from the Python C API to
no more expose complex and private atomic types. Atomic types depends on the
compiler or can even depend on compiler options. The new function
_PyThreadState_UncheckedGet() allows to get the variable value without having
to care of the exact implementation of atomic types.

Changes:

* Replace direct usage of the _PyThreadState_Current variable with a call to
  _PyThreadState_UncheckedGet().
* In pystate.c, replace direct usage of the _PyThreadState_Current variable
  with the PyThreadState_GET() macro for readability.
* Document also PyThreadState_Get() in pystate.h

1 files changed, 10 insertions, 0 deletions

diff --git a/Include/pystate.h b/Include/pystate.h
index 6000b81..b50b16b 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -168,7 +168,17 @@ PyAPI_FUNC(void) PyThreadState_DeleteCurrent(void);
 PyAPI_FUNC(void) _PyGILState_Reinit(void);
 #endif
 
+/* Return the current thread state. The global interpreter lock must be held.
+ * When the current thread state is NULL, this issues a fatal error (so that
+ * the caller needn't check for NULL). */
 PyAPI_FUNC(PyThreadState *) PyThreadState_Get(void);
+
+#ifdef WITH_THREAD
+/* Similar to PyThreadState_Get(), but don't issue a fatal error
+ * if it is NULL. */
+PyAPI_FUNC(PyThreadState *) _PyThreadState_UncheckedGet(void);
+#endif
+
 PyAPI_FUNC(PyThreadState *) PyThreadState_Swap(PyThreadState *);
 PyAPI_FUNC(PyObject *) PyThreadState_GetDict(void);
 PyAPI_FUNC(int) PyThreadState_SetAsyncExc(long, PyObject *);