Issue #1445: Fix a SystemError when accessing the ``cell_contents``
attribute of an empty cell object. Now a ValueError is raised.
Backport of r59170.
diff --git a/Lib/test/test_funcattrs.py b/Lib/test/test_funcattrs.py
index 7a083b7..a32be38 100644
--- a/Lib/test/test_funcattrs.py
+++ b/Lib/test/test_funcattrs.py
@@ -242,6 +242,17 @@
verify(c[0].__class__.__name__ == "cell") # don't have a type object handy
cantset(f, "func_closure", c)
+def test_empty_cell():
+ def f(): print a
+ try:
+ f.func_closure[0].cell_contents
+ except ValueError:
+ pass
+ else:
+ raise TestFailed, "shouldn't be able to read an empty cell"
+
+ a = 12
+
def test_func_doc():
def f(): pass
verify(f.__doc__ is None)
@@ -385,6 +396,7 @@
def testmore():
test_func_closure()
+ test_empty_cell()
test_func_doc()
test_func_globals()
test_func_name()
diff --git a/Misc/NEWS b/Misc/NEWS
index c633032..f856c1f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1,4 +1,4 @@
-+++++++++++
++++++++++++
Python News
+++++++++++
@@ -12,6 +12,9 @@
Core and builtins
-----------------
+- Issue #1445: Fix a SystemError when accessing the ``cell_contents``
+ attribute of an empty cell object.
+
- Issue #1265: Fix a problem with sys.settrace, if the tracing function uses a
generator expression when at the same time the executed code is closing a
paused generator.
diff --git a/Objects/cellobject.c b/Objects/cellobject.c
index 65a29aa..e659555 100644
--- a/Objects/cellobject.c
+++ b/Objects/cellobject.c
@@ -89,7 +89,12 @@
static PyObject *
cell_get_contents(PyCellObject *op, void *closure)
{
- Py_XINCREF(op->ob_ref);
+ if (op->ob_ref == NULL)
+ {
+ PyErr_SetString(PyExc_ValueError, "Cell is empty");
+ return NULL;
+ }
+ Py_INCREF(op->ob_ref);
return op->ob_ref;
}