GH-107724: Fix the signature of PY_THROW callback functions.

Include/internal/pycore_instruments.h

@@ -90,10 +90,6 @@ extern int
 _Py_call_instrumentation_2args(PyThreadState *tstate, int event,
     _PyInterpreterFrame *frame, _Py_CODEUNIT *instr, PyObject *arg0, PyObject *arg1);
 
-extern void
-_Py_call_instrumentation_exc0(PyThreadState *tstate, int event,
-    _PyInterpreterFrame *frame, _Py_CODEUNIT *instr);
-
 extern void
 _Py_call_instrumentation_exc2(PyThreadState *tstate, int event,
     _PyInterpreterFrame *frame, _Py_CODEUNIT *instr, PyObject *arg0, PyObject *arg1);

Lib/test/test_monitoring.py

@@ -709,6 +709,7 @@ def check_events(self, func, expected, tool=TEST_TOOL, recorders=(ExceptionRecor
 
     def check_balanced(self, func, recorders):
         events = self.get_events(func, TEST_TOOL, recorders)
+        print("----\n", events, "\n------")
         self.assertEqual(len(events)%2, 0)
         for r, h in zip(events[::2],events[1::2]):
             r0 = r[0]
@@ -743,6 +744,13 @@ class ExceptionHandledRecorder(ExceptionRecorder):
     def __call__(self, code, offset, exc):
         self.events.append(("handled", type(exc)))
 
+class ThrowRecorder(ExceptionRecorder):
+
+    event_type = E.PY_THROW
+
+    def __call__(self, code, offset, exc):
+        self.events.append(("throw", type(exc)))
+
 class ExceptionMonitoringTest(CheckEvents):
 
 
@@ -888,6 +896,31 @@ async def async_loop():
             func,
             recorders = self.exception_recorders)
 
+    def test_throw(self):
+
+        def gen():
+            yield 1
+            yield 2
+
+        def func():
+            try:
+                g = gen()
+                next(g)
+                g.throw(IndexError)
+            except IndexError:
+                pass
+
+        self.check_balanced(
+            func,
+            recorders = self.exception_recorders)
+
+        events = self.get_events(
+            func,
+            TEST_TOOL,
+            self.exception_recorders + (ThrowRecorder,)
+        )
+        self.assertEqual(events[0], ("throw", IndexError))
+
 class LineRecorder:
 
     event_type = E.LINE

Misc/NEWS.d/next/Core and Builtins/2023-08-04-21-25-26.gh-issue-107724.EbBXMr.rst

@@ -0,0 +1,3 @@
+In pre-release versions of 3.12, up to rc1, the sys.monitoring callback
+function for the ``PY_THROW`` event was missing the third, exception
+argument. That is now fixed.

Python/ceval.c

@@ -2017,7 +2017,7 @@ monitor_throw(PyThreadState *tstate,
     if (no_tools_for_event(tstate, frame, PY_MONITORING_EVENT_PY_THROW)) {
         return;
     }
-    _Py_call_instrumentation_exc0(tstate, PY_MONITORING_EVENT_PY_THROW, frame, instr);
+    do_monitor_exc(tstate, frame, instr, PY_MONITORING_EVENT_PY_THROW);
 }
 
 void

Python/instrumentation.c

@@ -1081,16 +1081,6 @@ call_instrumentation_vector_protected(
     assert(_PyErr_Occurred(tstate));
 }
 
-void
-_Py_call_instrumentation_exc0(
-    PyThreadState *tstate, int event,
-    _PyInterpreterFrame *frame, _Py_CODEUNIT *instr)
-{
-    assert(_PyErr_Occurred(tstate));
-    PyObject *args[3] = { NULL, NULL, NULL };
-    call_instrumentation_vector_protected(tstate, event, frame, instr, 2, args);
-}
-
 void
 _Py_call_instrumentation_exc2(
     PyThreadState *tstate, int event,

Python/legacy_tracing.c

@@ -163,7 +163,7 @@ sys_trace_func2(
 }
 
 static PyObject *
-sys_trace_unwind(
+sys_trace_func3(
     _PyLegacyEventHandler *self, PyObject *const *args,
     size_t nargsf, PyObject *kwnames
 ) {
@@ -445,7 +445,7 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
             return -1;
         }
         if (set_callbacks(PY_MONITORING_SYS_TRACE_ID,
-            (vectorcallfunc)sys_trace_func2, PyTrace_CALL,
+            (vectorcallfunc)sys_trace_func3, PyTrace_CALL,
                         PY_MONITORING_EVENT_PY_THROW, -1)) {
             return -1;
         }
@@ -470,7 +470,7 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
             return -1;
         }
         if (set_callbacks(PY_MONITORING_SYS_TRACE_ID,
-            (vectorcallfunc)sys_trace_unwind, PyTrace_RETURN,
+            (vectorcallfunc)sys_trace_func3, PyTrace_RETURN,
                         PY_MONITORING_EVENT_PY_UNWIND, -1)) {
             return -1;
         }