feat: handle logical assignment in no-self-assign

[Zzzen]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[x] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

What rule do you want to change?
no-self-assign

Does this change cause the rule to produce more or fewer warnings?
more warnings

How will the change be implemented? (New option, new default behavior, etc.)?
new default behavior

Please provide some example code that this change will affect:

a &= a;  
a |= a;
a &&= a;
a ||= a;
a ??= a;

What does the rule currently do for this code?
no errors are reported

What will the rule do after it's changed?
all lines will be reported.

What changes did you make? (Give an overview)

currently, only = is handled in no-self-assign. But other logical assignment operators work roughly the same as =.

a &&= a is a && (a = a), which is essentially a noop.

Is there anything you'd like reviewers to focus on?

[mdjermanovic]

Hi @Zzzen, thanks for the PR!

We listed adding support for &&=, ||=, and ??= operators to the no-self-assign rule as maybe in #13569. We're not yet sure if that change makes sense, so I marked this as "evaluating".

As for &= and |=, I think that's different as it involves a calculation before the assignment, and it doesn't have to be a noop (should be for integers, but e.g, 1.5 | 1.5 is 1, null | null is 0, etc.), so those checks probably don't belong to no-self-assign.

[Zzzen]

Ooops, did not notice the issue. IMO, even though |= may have side effects on non-integers, a |= a is likely a typo and should be disallowed like how object properties are handled.

[eslint-github-bot]

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[mdjermanovic]

@eslint/eslint-tsc thoughts about this proposal for the no-self-assign rule?

• Should it report a &&= a, a ||= a, and a ??= a? I think this makes sense since these are essentially the same as a = a.
• Should it report a &= a, and a |= a? I think this doesn't belong to this rule, for the reasons described in this comment.

[nzakas]

@mdjermanovic i agree with your reasoning.

[btmills]

@mdjermanovic I agree as well.

[mdjermanovic]

@Zzzen sorry for the delay, the change for &&=, ||=, and ??= is accepted now.

Can you also update the documentation for this rule?

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Zzzen (28715cf, 2dc996f)

[Zzzen]

👌 updated

[mdjermanovic]

LGTM, thanks!