gh-149309: Use BaseException as BdbQuit's base class

Doc/whatsnew/3.15.rst

@@ -788,6 +788,15 @@ base64
   (Contributed by Gregory P. Smith in :gh:`146311`.)
 
 
+bdb
+---
+
+* :exc:`bdb.BdbQuit` is now a subclass of :exc:`BaseException`, instead of
+  :exc:`Exception`, to allow it to be used for cleanly exiting the debugger without
+  being accidentally caught by user code.
+  (Contributed by Tian Gao in :gh:`149337`.)
+
+
 binascii
 --------
 

Lib/bdb.py

@@ -13,7 +13,7 @@
 GENERATOR_AND_COROUTINE_FLAGS = CO_GENERATOR | CO_COROUTINE | CO_ASYNC_GENERATOR
 
 
-class BdbQuit(Exception):
+class BdbQuit(BaseException):
     """Exception to give up completely."""
 
 

Lib/test/test_bdb.py

@@ -1237,6 +1237,15 @@ def test_format_stack_entry_no_lineno(self):
         self.assertIn('Warning: lineno is None',
                       Bdb().format_stack_entry((sys._getframe(), None)))
 
+    def test_bdb_quit_base_exception(self):
+        # gh-149309
+        try:
+            raise _bdb.BdbQuit()
+        except Exception:
+            self.fail(f'BdbQuit should not be caught by Exception')
+        except BaseException:
+            pass
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2026-05-03-22-52-07.gh-issue-149309.gXhk9Y.rst

@@ -0,0 +1 @@
+:exc:`bdb.BdbQuit` is now a subclass of :exc:`BaseException`, instead of :exc:`Exception`, to allow it to be used for cleanly exiting the debugger without being accidentally caught by user code.