gh-128991: Release the enter frame reference within bdb callback (#128992)

* Release the enter frame reference within bdb callback

* 📜🤖 Added by blurb_it.

---------

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Lib/bdb.py

@@ -4,6 +4,7 @@ import fnmatch
 import sys
 import os
 import weakref
+from contextlib import contextmanager
 from inspect import CO_GENERATOR, CO_COROUTINE, CO_ASYNC_GENERATOR
 
 __all__ = ["BdbQuit", "Bdb", "Breakpoint"]
@@ -65,6 +66,12 @@ class Bdb:
         self.botframe = None
         self._set_stopinfo(None, None)
 
+    @contextmanager
+    def set_enterframe(self, frame):
+        self.enterframe = frame
+        yield
+        self.enterframe = None
+
     def trace_dispatch(self, frame, event, arg):
         """Dispatch a trace function for debugged frames based on the event.
 
@@ -90,8 +97,7 @@ class Bdb:
         The arg parameter depends on the previous event.
         """
 
-        self.enterframe = frame
-
+        with self.set_enterframe(frame):
             if self.quitting:
                 return # None
             if event == 'line':
@@ -395,7 +401,7 @@ class Bdb:
         if frame is None:
             frame = sys._getframe().f_back
         self.reset()
-        self.enterframe = frame
+        with self.set_enterframe(frame):
             while frame:
                 frame.f_trace = self.trace_dispatch
                 self.botframe = frame
@@ -404,7 +410,6 @@ class Bdb:
                 frame.f_trace_lines = True
                 frame = frame.f_back
             self.set_stepinstr()
-        self.enterframe = None
         sys.settrace(self.trace_dispatch)
 
     def set_continue(self):
@@ -424,7 +429,6 @@ class Bdb:
             for frame, (trace_lines, trace_opcodes) in self.frame_trace_lines_opcodes.items():
                 frame.f_trace_lines, frame.f_trace_opcodes = trace_lines, trace_opcodes
             self.frame_trace_lines_opcodes = {}
-            self.enterframe = None
 
     def set_quit(self):
         """Set quitting attribute to True.

Misc/NEWS.d/next/Library/2025-01-18-16-58-10.gh-issue-128991.EzJit9.rst

@@ -0,0 +1 @@
+Release the enter frame reference within :mod:`bdb` callback