Make sure that modification to frame.f_locals outside of trace functi…

…on do not show up after tracing.
python · markshannon · Mar 25, 2022 · Mar 22, 2022 · Mar 22, 2022 · Mar 23, 2022
commit c017590a96b8a9558923481884fa97d032ffb07b
@@ -930,6 +930,13 @@ call_trampoline(PyThreadState *tstate, PyObject* callback,
     stack[1] = whatstrings[what];
     stack[2] = (arg != NULL) ? arg : Py_None;
 
+    /* Discard any previous modifications the frame's fast locals */
+    if (frame->f_fast_as_locals) {
+        if (PyFrame_FastToLocalsWithError(frame) < 0) {
+            return NULL;
+        }
+    }
+
     /* call the Python-level function */
     PyObject *result = _PyObject_FastCallTstate(tstate, callback, stack, 3);