bpo-33018: Improve issubclass() error checking and message. (GH-5944)
This improves error message for situations when a non-class is
checked w.r.t. an abstract base class.
diff --git a/Lib/_py_abc.py b/Lib/_py_abc.py
index 6f42ef3..3c3aa8e 100644
--- a/Lib/_py_abc.py
+++ b/Lib/_py_abc.py
@@ -107,6 +107,8 @@
def __subclasscheck__(cls, subclass):
"""Override for issubclass(subclass, cls)."""
+ if not isinstance(subclass, type):
+ raise TypeError('issubclass() arg 1 must be a class')
# Check cache
if subclass in cls._abc_cache:
return True
diff --git a/Misc/ACKS b/Misc/ACKS
index d752d8a..05932a8 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -202,6 +202,7 @@
Richard Brodie
Michael Broghton
Ammar Brohi
+Josh Bronson
Daniel Brotsky
Jean Brouwers
Gary S. Brown
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-03-22-23-09-06.bpo-33018.0ncEJV.rst b/Misc/NEWS.d/next/Core and Builtins/2018-03-22-23-09-06.bpo-33018.0ncEJV.rst
new file mode 100644
index 0000000..e799e98
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-03-22-23-09-06.bpo-33018.0ncEJV.rst
@@ -0,0 +1,3 @@
+Improve consistency of errors raised by ``issubclass()`` when called with a
+non-class and an abstract base class as the first and second arguments,
+respectively. Patch by Josh Bronson.
diff --git a/Modules/_abc.c b/Modules/_abc.c
index 8628839..7daa18e 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -569,6 +569,11 @@
PyObject *subclass)
/*[clinic end generated code: output=b56c9e4a530e3894 input=1d947243409d10b8]*/
{
+ if (!PyType_Check(subclass)) {
+ PyErr_SetString(PyExc_TypeError, "issubclass() arg 1 must be a class");
+ return NULL;
+ }
+
PyObject *ok, *mro = NULL, *subclasses = NULL, *result = NULL;
Py_ssize_t pos;
int incache;