Add FRAME_UNWINDING to mark unwinding state.

Author: markshannon

Include/cpython/frameobject.h

@@ -12,8 +12,9 @@ enum _framestate {
     FRAME_SUSPENDED = -1,
     FRAME_EXECUTING = 0,
     FRAME_RETURNED = 1,
-    FRAME_RAISED = 2,
-    FRAME_CLEARED = 3
+    FRAME_UNWINDING = 2,
+    FRAME_RAISED = 3,
+    FRAME_CLEARED = 4
 };
 
 typedef signed char PyFrameState;

Objects/frameobject.c

@@ -369,6 +369,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
                      "can't jump from the 'call' trace event of a new frame");
             return -1;
         case FRAME_RETURNED:
+        case FRAME_UNWINDING:
         case FRAME_RAISED:
         case FRAME_CLEARED:
             PyErr_SetString(PyExc_ValueError,

Python/ceval.c

@@ -3769,14 +3769,14 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
         PyTraceBack_Here(f);
 
         if (tstate->c_tracefunc != NULL) {
-            /* Temporarily set frame state to RAISED for benefit of frame.setlineno */
+            /* Make sure state is set to FRAME_EXECUTING for tracing */
             assert(f->f_state == FRAME_EXECUTING);
-            f->f_state = FRAME_RAISED;
+            f->f_state = FRAME_UNWINDING;
             call_exc_trace(tstate->c_tracefunc, tstate->c_traceobj,
                            tstate, f);
-            f->f_state = FRAME_EXECUTING;
         }
 exception_unwind:
+        f->f_state = FRAME_UNWINDING;
         /* Unwind stacks if an exception occurred */
         while (f->f_iblock > 0) {
             /* Pop the current block. */
@@ -3835,6 +3835,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
                     }
                 }
                 /* Resume normal execution */
+                f->f_state = FRAME_EXECUTING;
                 goto main_loop;
             }
         } /* unwind stack */