PySequence_Check: argument is dereferenced and then checked for NULL

[izbyshev]

BPO	34504
Nosy	@benjaminp, @berkerpeksag, @serhiy-storchaka, @izbyshev, @miss-islington
PRs	bpo-34504: Remove the redundant NULL check in PySequence_Check() #8935 [3.7] closes bpo-34504: Remove the useless NULL check in PySequence_Check(). (GH-8935) #8936 [3.6] closes bpo-34504: Remove the useless NULL check in PySequence_Check(). (GH-8935) #8937

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2018-08-25.23:52:30.020>
created_at = <Date 2018-08-25.21:05:49.680>
labels = ['interpreter-core', '3.8', 'type-bug', '3.7']
title = 'PySequence_Check: argument is dereferenced and then checked for NULL'
updated_at = <Date 2018-08-26.00:14:40.621>
user = 'https://github.com/izbyshev'

bugs.python.org fields:

activity = <Date 2018-08-26.00:14:40.621>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2018-08-25.23:52:30.020>
closer = 'benjamin.peterson'
components = ['Interpreter Core']
creation = <Date 2018-08-25.21:05:49.680>
creator = 'izbyshev'
dependencies = []
files = []
hgrepos = []
issue_num = 34504
keywords = ['patch']
message_count = 4.0
messages = ['324101', '324107', '324108', '324109']
nosy_count = 5.0
nosy_names = ['benjamin.peterson', 'berker.peksag', 'serhiy.storchaka', 'izbyshev', 'miss-islington']
pr_nums = ['8935', '8936', '8937']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34504'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

[izbyshev]

The argument of PySequence_Check() is dereferenced at

cpython/Objects/abstract.c

Line 1511 in 5f79b50

if (PyDict_Check(s))

and then checked for NULL.

Reported by Svace static analyzer.

Since other PySomething_Check() functions seem to expect a non-NULL argument, I suggest to remove the NULL check instead of moving it.

[benjaminp]

New changeset b57b4ac by Benjamin Peterson (Alexey Izbyshev) in branch 'master':
closes bpo-34504: Remove the useless NULL check in PySequence_Check(). (GH-8935)
b57b4ac

[miss-islington]

New changeset d6725fc by Miss Islington (bot) in branch '3.7':
closes bpo-34504: Remove the useless NULL check in PySequence_Check(). (GH-8935)
d6725fc

[miss-islington]

New changeset d60bdf2 by Miss Islington (bot) in branch '3.6':
closes bpo-34504: Remove the useless NULL check in PySequence_Check(). (GH-8935)
d60bdf2