[3.11] GH-65052: Prevent pdb from crashing when trying to display objects (GH-111002)

(cherry picked from commit c523ce0f434582580a3721e15cb7dd6b56ad0236)

1 files changed, 16 insertions, 7 deletions

diff --git a/Lib/pdb.py b/Lib/pdb.py
index fe9eab9..5dfe507 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -405,8 +405,9 @@ class Pdb(bdb.Bdb, cmd.Cmd):
                 # fields are changed to be displayed
                 if newvalue is not oldvalue and newvalue != oldvalue:
                     displaying[expr] = newvalue
-                    self.message('display %s: %r  [old: %r]' %
-                                 (expr, newvalue, oldvalue))
+                    self.message('display %s: %s  [old: %s]' %
+                                 (expr, self._safe_repr(newvalue, expr),
+                                  self._safe_repr(oldvalue, expr)))
 
     def interaction(self, frame, traceback):
         # Restore the previous signal handler at the Pdb prompt.
@@ -1221,7 +1222,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         for i in range(n):
             name = co.co_varnames[i]
             if name in dict:
-                self.message('%s = %r' % (name, dict[name]))
+                self.message('%s = %s' % (name, self._safe_repr(dict[name], name)))
             else:
                 self.message('%s = *** undefined ***' % (name,))
     do_a = do_args
@@ -1231,7 +1232,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         Print the return value for the last return of a function.
         """
         if '__return__' in self.curframe_locals:
-            self.message(repr(self.curframe_locals['__return__']))
+            self.message(self._safe_repr(self.curframe_locals['__return__'], "retval"))
         else:
             self.error('Not yet returned!')
     do_rv = do_retval
@@ -1268,6 +1269,12 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         except:
             self._error_exc()
 
+    def _safe_repr(self, obj, expr):
+        try:
+            return repr(obj)
+        except Exception as e:
+            return _rstr(f"*** repr({expr}) failed: {self._format_exc(e)} ***")
+
     def do_p(self, arg):
         """p expression
         Print the value of the expression.
@@ -1438,12 +1445,12 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         """
         if not arg:
             self.message('Currently displaying:')
-            for item in self.displaying.get(self.curframe, {}).items():
-                self.message('%s: %r' % item)
+            for key, val in self.displaying.get(self.curframe, {}).items():
+                self.message('%s: %s' % (key, self._safe_repr(val, key)))
         else:
             val = self._getval_except(arg)
             self.displaying.setdefault(self.curframe, {})[arg] = val
-            self.message('display %s: %r' % (arg, val))
+            self.message('display %s: %s' % (arg, self._safe_repr(val, arg)))
 
     complete_display = _complete_expression
 
@@ -1645,6 +1652,8 @@ class Pdb(bdb.Bdb, cmd.Cmd):
 
         self.run(target.code)
 
+    def _format_exc(self, exc: BaseException):
+        return traceback.format_exception_only(exc)[-1].strip()
 
     def _getsourcelines(self, obj):
         # GH-103319