Issue #16402: In range slicing, fix shadowing of exceptions from __index__ method.

mdickinson · mdickinson · commit 8cd1c7681d86 · 2012-11-04T11:46:17.000Z
diff --git a/Lib/test/test_range.py b/Lib/test/test_range.py
@@ -312,6 +312,15 @@ def __index__(self):
 
         self.assertRaises(TypeError, range, IN())
 
+        # Test use of user-defined classes in slice indices.
+        self.assertEqual(list(range(10)[:I(5)]), list(range(5)))
+
+        with self.assertRaises(RuntimeError):
+            range(0, 10)[:IX()]
+
+        with self.assertRaises(TypeError):
+            range(0, 10)[:IN()]
+
     def test_count(self):
         self.assertEqual(range(3).count(-1), 0)
         self.assertEqual(range(3).count(0), 1)
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.2.4
 Core and Builtins
 -----------------
 
+- Issue #16402: When slicing a range, fix shadowing of exceptions from
+  __index__.
+
 - Issue #16336: fix input checking in the surrogatepass error handler.
   Patch by Serhiy Storchaka.
 
diff --git a/Objects/rangeobject.c b/Objects/rangeobject.c
@@ -330,11 +330,11 @@ compute_slice_element(PyObject *obj)
         if (PyIndex_Check(obj)) {
             result = PyNumber_Index(obj);
         }
-    }
-    if (result == NULL) {
-        PyErr_SetString(PyExc_TypeError,
-                        "slice indices must be integers or "
-                        "None or have an __index__ method");
+        else {
+            PyErr_SetString(PyExc_TypeError,
+                            "slice indices must be integers or "
+                            "None or have an __index__ method");
+        }
     }
     return result;
 }

Original file line number	Diff line number	Diff line change
`@@ -330,11 +330,11 @@ compute_slice_element(PyObject *obj)`
`330`	`330`	`if (PyIndex_Check(obj)) {`
`331`	`331`	`result = PyNumber_Index(obj);`
`332`	`332`	`}`
`333`		`- }`
`334`		`- if (result == NULL) {`
`335`		`- PyErr_SetString(PyExc_TypeError,`
`336`		`- "slice indices must be integers or "`
`337`		`- "None or have an __index__ method");`
	`333`	`+ else {`
	`334`	`+ PyErr_SetString(PyExc_TypeError,`
	`335`	`+ "slice indices must be integers or "`
	`336`	`+ "None or have an __index__ method");`
	`337`	`+ }`
`338`	`338`	`}`
`339`	`339`	`return result;`
`340`	`340`	`}`