cpython/Misc/NEWS.d/next/Core and Builtins/2017-09-26-13-03-16.bpo-315...

Raise a `TypeError` with a helpful error message when class creation fails
due to a metaclass with a bad ``__prepare__()`` method. Patch by Oren Milman.
[3.6] bpo-31588: Validate return value of __prepare__() methods (GH-3790) Class execution requires that __prepare__() methods return a proper execution namespace. Check for that immediately after calling __prepare__(), rather than passing it through to the code execution machinery and potentially triggering SystemError (in debug builds) or a cryptic TypeError (in release builds). Patch by Oren Milman. (cherry picked from commit 5837d0418f47933b2e3c139bdee8a79c248a943c) 2017-09-27 13:21:33 -03:00			Raise a `TypeError` with a helpful error message when class creation fails
			due to a metaclass with a bad ``__prepare__()`` method. Patch by Oren Milman.