merge from 3.4

Lib/pdb.py

@@ -1669,6 +1669,9 @@ def main():
             # In most cases SystemExit does not warrant a post-mortem session.
             print("The program exited via sys.exit(). Exit status:", end=' ')
             print(sys.exc_info()[1])
+        except SyntaxError:
+            traceback.print_exc()
+            sys.exit(1)
         except:
             traceback.print_exc()
             print("Uncaught exception. Entering post mortem debugging")

Lib/test/test_pdb.py

@@ -1043,6 +1043,18 @@ class PdbTestCase(unittest.TestCase):
         self.assertNotIn('Error', stdout.decode(),
                          "Got an error running test script under PDB")
 
+    def test_issue16180(self):
+        # A syntax error in the debuggee.
+        script = "def f: pass\n"
+        commands = ''
+        expected = "SyntaxError:"
+        stdout, stderr = self.run_pdb(script, commands)
+        self.assertIn(expected, stdout,
+            '\n\nExpected:\n{}\nGot:\n{}\n'
+            'Fail to handle a syntax error in the debuggee.'
+            .format(expected, stdout))
+
+
     def tearDown(self):
         support.unlink(support.TESTFN)
 

Misc/NEWS

@@ -14,6 +14,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #16180: Exit pdb if file has syntax error, instead of trapping user
+  in an infinite loop.  Patch by Xavier de Gaye.
+
 - Issue #24891: Fix a race condition at Python startup if the file descriptor
   of stdin (0), stdout (1) or stderr (2) is closed while Python is creating
   sys.stdin, sys.stdout and sys.stderr objects. These attributes are now set