bpo-40824: Do not mask errors in __iter__ in "in" and the operator module. (GH-20537)

miss-islington · serhiy-storchaka · web-flow · commit 353c4bab7d10 · 2020-06-22T01:20:56.000-07:00
Unexpected errors in calling the __iter__ method are no longer masked by TypeError in the "in" operator and functions operator.contains(), operator.indexOf() and operator.countOf(). (cherry picked from commit cafe1b6) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py
@@ -76,6 +76,10 @@ def __getitem__(self, i):
         return i
     __iter__ = None
 
+class BadIterableClass:
+    def __iter__(self):
+        raise ZeroDivisionError
+
 # Main test suite
 
 class TestCase(unittest.TestCase):
@@ -658,6 +662,7 @@ def test_in_and_not_in(self):
 
         self.assertRaises(TypeError, lambda: 3 in 12)
         self.assertRaises(TypeError, lambda: 3 not in map)
+        self.assertRaises(ZeroDivisionError, lambda: 3 in BadIterableClass())
 
         d = {"one": 1, "two": 2, "three": 3, 1j: 2j}
         for k in d:
@@ -740,6 +745,7 @@ def test_indexOf(self):
 
         self.assertRaises(TypeError, indexOf, 42, 1)
         self.assertRaises(TypeError, indexOf, indexOf, indexOf)
+        self.assertRaises(ZeroDivisionError, indexOf, BadIterableClass(), 1)
 
         f = open(TESTFN, "w")
         try:
@@ -1027,6 +1033,7 @@ def test_free_after_iterating(self):
     def test_error_iter(self):
         for typ in (DefaultIterClass, NoIterClass):
             self.assertRaises(TypeError, iter, typ())
+        self.assertRaises(ZeroDivisionError, iter, BadIterableClass())
 
 
 def test_main():
diff --git a/Lib/test/test_operator.py b/Lib/test/test_operator.py
@@ -35,6 +35,10 @@ def __mul__(self, other):
     def __rmul__(self, other):
         return other * self.lst
 
+class BadIterable:
+    def __iter__(self):
+        raise ZeroDivisionError
+
 
 class OperatorTestCase:
     def test_lt(self):
@@ -142,6 +146,7 @@ def test_countOf(self):
         operator = self.module
         self.assertRaises(TypeError, operator.countOf)
         self.assertRaises(TypeError, operator.countOf, None, None)
+        self.assertRaises(ZeroDivisionError, operator.countOf, BadIterable(), 1)
         self.assertEqual(operator.countOf([1, 2, 1, 3, 1, 4], 3), 1)
         self.assertEqual(operator.countOf([1, 2, 1, 3, 1, 4], 5), 0)
 
@@ -176,6 +181,7 @@ def test_indexOf(self):
         operator = self.module
         self.assertRaises(TypeError, operator.indexOf)
         self.assertRaises(TypeError, operator.indexOf, None, None)
+        self.assertRaises(ZeroDivisionError, operator.indexOf, BadIterable(), 1)
         self.assertEqual(operator.indexOf([4, 3, 2, 1], 3), 1)
         self.assertRaises(ValueError, operator.indexOf, [4, 3, 2, 1], 0)
 
@@ -258,6 +264,7 @@ def test_contains(self):
         operator = self.module
         self.assertRaises(TypeError, operator.contains)
         self.assertRaises(TypeError, operator.contains, None, None)
+        self.assertRaises(ZeroDivisionError, operator.contains, BadIterable(), 1)
         self.assertTrue(operator.contains(range(4), 2))
         self.assertFalse(operator.contains(range(4), 5))
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-05-30-14-37-18.bpo-40824.XR3V5s.rst b/Misc/NEWS.d/next/Core and Builtins/2020-05-30-14-37-18.bpo-40824.XR3V5s.rst
@@ -0,0 +1,4 @@
+Unexpected errors in calling the ``__iter__`` method are no longer masked by
+``TypeError`` in the :keyword:`in` operator and functions
+:func:`~operator.contains`, :func:`~operator.indexOf` and
+:func:`~operator.countOf` of the :mod:`operator` module.
diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -2058,7 +2058,9 @@ _PySequence_IterSearch(PyObject *seq, PyObject *obj, int operation)
 
     it = PyObject_GetIter(seq);
     if (it == NULL) {
-        type_error("argument of type '%.200s' is not iterable", seq);
+        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            type_error("argument of type '%.200s' is not iterable", seq);
+        }
         return -1;
     }
 

Original file line number	Diff line number	Diff line change
`@@ -2058,7 +2058,9 @@ _PySequence_IterSearch(PyObject seq, PyObject obj, int operation)`
`2058`	`2058`
`2059`	`2059`	`it = PyObject_GetIter(seq);`
`2060`	`2060`	`if (it == NULL) {`
`2061`		`- type_error("argument of type '%.200s' is not iterable", seq);`
	`2061`	`+ if (PyErr_ExceptionMatches(PyExc_TypeError)) {`
	`2062`	`+ type_error("argument of type '%.200s' is not iterable", seq);`
	`2063`	`+ }`
`2062`	`2064`	`return -1;`
`2063`	`2065`	`}`
`2064`	`2066`