Issue 1011: Non strict operation with slice

[skv0zsneg]

I have made things!

Checklist

• I have double checked that there are no unrelated changes in this pull request (old patches, accidental config files, etc)
• I have created at least one test case for the changes I have made
• I have updated the documentation for the changes I have made
• I have added my changes to the CHANGELOG.md

Related issues

• Refs Enforce stricter slice operations #1011

Description

Hi! I've add non strict slice operation checking. I guess there is can be some use cases that I might not have remembered. Hope we can figure this out 🤝

[sobolevn]

items = part is not needed

[sobolevn]

Suggested change

	def visit_Slice(self, node: ast.Slice):
	def visit_Slice(self, node: ast.Slice) -> None:

[sobolevn]

Suggested change

	def _check_reverse_through_slice(self, node: ast.Slice):
	def _check_reverse_through_slice(self, node: ast.Slice) -> None:

(and all other places)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e1d1084) to head (c483b16).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #3373   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          361       362    +1     
  Lines        11830     11881   +51     
  Branches       808       815    +7     
=========================================
+ Hits         11830     11881   +51     

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[sobolevn]

Suggested change

	'other = items[:]',
	'other = items[::]',
	# pop
	'items = items[:-1]',
	'some, items = "some", items[:-1]',
	'items[:]',
	'items[::]',
	# pop
	'items[:-1]',
	'items[None:-1]',
	'items[None:-1:1]',

[sobolevn]

Don't forget to test corner cases with None and explicit steps.

[sobolevn]

Sorry, I don't udnerstand why this works. It should always raise an error. [:] slice must be forbidden by this rule.

[skv0zsneg]

This works because I check assign node for closest parent before add violation. Will fix it 👍

[sobolevn]

Suggested change

	'a = items[0]',
	'items[0:]',

[sobolevn]

Suggested change

	'a = items[1::-1]',
	'items[1::-1]',
	'items[1:4:-1]',
	'items[:x]',
	'items[:-x]',
	'items[::-x]',
	'items[::x]',

[sobolevn]

Suggested change

	# bad
	items = items[::-1]
	# good
	items.reverse()
	# bad
	other = items[:]
	# good
	other = items.copy()
	# bad
	items = items[:-1]
	# good
	items.pop()
	# Correct:
	items.reverse()
	items.copy()
	items.pop()
	# Wrong:
	items[::-1] # .reverse()
	items[:] # .copy()
	items[:-1] # .pop()