(Merge 3.2) Close #12085: Fix an attribute error in subprocess.Popen destructor

if the constructor has failed, e.g. because of an undeclared keyword argument.
Patch written by Oleg Oshmyan.

Lib/subprocess.py

@@ -775,7 +775,10 @@ class Popen(object):
         self.wait()
 
     def __del__(self, _maxsize=sys.maxsize, _active=_active):
-        if not self._child_created:
+        # If __init__ hasn't had a chance to execute (e.g. if it
+        # was passed an undeclared keyword argument), we don't
+        # have a _child_created attribute at all.
+        if not getattr(self, '_child_created', False):
             # We didn't get to successfully create a child process.
             return
         # In case the child hasn't been waited on, check if it's done.

Lib/test/test_subprocess.py

@@ -146,6 +146,16 @@ class ProcessTestCase(BaseTestCase):
                              env=newenv)
         self.assertEqual(rc, 1)
 
+    def test_invalid_args(self):
+        # Popen() called with invalid arguments should raise TypeError
+        # but Popen.__del__ should not complain (issue #12085)
+        with support.captured_stderr() as s:
+            self.assertRaises(TypeError, subprocess.Popen, invalid_arg_name=1)
+            argcount = subprocess.Popen.__init__.__code__.co_argcount
+            too_many_args = [0] * (argcount + 1)
+            self.assertRaises(TypeError, subprocess.Popen, *too_many_args)
+        self.assertEqual(s.getvalue(), '')
+
     def test_stdin_none(self):
         # .stdin is None when not redirected
         p = subprocess.Popen([sys.executable, "-c", 'print("banana")'],

Misc/ACKS

@@ -688,6 +688,7 @@ Piet van Oostrum
 Jason Orendorff
 Douglas Orr
 Michele Orrù
+Oleg Oshmyan
 Denis S. Otkidach
 Michael Otteneder
 R. M. Oudkerk

Misc/NEWS

@@ -184,6 +184,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #12085: Fix an attribute error in subprocess.Popen destructor if the
+  constructor has failed, e.g. because of an undeclared keyword argument. Patch
+  written by Oleg Oshmyan.
+
 - Issue #12028: Make threading._get_ident() public, rename it to
   threading.get_ident() and document it. This function was already used using
   _thread.get_ident().