New submission from Adam Cmiel <acmi...@gmail.com>:
Python version: Python 3.8.3 (default, May 15 2020, 00:00:00) [GCC 10.1.1 20200507 (Red Hat 10.1.1-1)] on linux Description: When assigning to a tuple index using +=, if the element at that index is a list, the list is extended and a TypeError is raised. a = ([],) try: a[0] += [1] except TypeError: assert a != ([1],) # assertion fails else: assert a == ([1],) The expected behaviour is that only one of those things would happen (probably the list being extended with no error, given that a[0].extend([1]) works fine). ---------- components: Interpreter Core messages: 370990 nosy: Adam Cmiel priority: normal severity: normal status: open title: Unexpected behaviour for += assignment to list inside tuple type: behavior versions: Python 3.8 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue40911> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com