bpo-34266: [pdb] handle ValueError from shlex.split()

Lib/pdb.py

@@ -1026,7 +1026,11 @@ def do_run(self, arg):
         if arg:
             import shlex
             argv0 = sys.argv[0:1]
-            sys.argv = shlex.split(arg)
+            try:
+                sys.argv = shlex.split(arg)
+            except ValueError as e:
+                self.error('Cannot run %s: %s' % (arg, e))
+                return
             sys.argv[:0] = argv0
         # this is caught in the main debugger loop
         raise Restart

Lib/test/test_pdb.py

@@ -1771,6 +1771,21 @@ def test_errors_in_command(self):
             '(Pdb) ',
         ])
 
+    def test_issue34266(self):
+        '''do_run handles exceptions from parsing its arg'''
+        def check(bad_arg, msg):
+            commands = "\n".join([
+                f'run {bad_arg}',
+                'q',
+            ])
+            stdout, _ = self.run_pdb_script('pass', commands + '\n')
+            self.assertEqual(stdout.splitlines()[1:], [
+                '-> pass',
+                f'(Pdb) *** Cannot run {bad_arg}: {msg}',
+                '(Pdb) ',
+            ])
+        check('\\', 'No escaped character')
+        check('\"', 'No closing quotation')
 
     def test_issue42384(self):
         '''When running `python foo.py` sys.path[0] is an absolute path. `python -m pdb foo.py` should behave the same'''

Misc/NEWS.d/next/Library/2021-06-10-21-53-46.bpo-34266.k3fxnm.rst

@@ -0,0 +1 @@
+Handle exceptions from parsing the arg of :mod:`pdb`'s run/restart command.