Add lint rule to disallow shadowing when it looks buggy #365
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sandersn
requested changes
Feb 18, 2025
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I think this is ready to go, although I had a few low-level questions about nil and copying.
The semantics are closer to a "compiler extension", where only legitimately incorrect code is illegal, and I'd prefer a "lint rule" style, where confusing or possibly-mistaken code is illegal too. But I don't mind either one for our code base as long as we're running something.
jakebailey
commented
Feb 18, 2025
|
Updated with some CFA changes; I actually really like how it is now. |
jakebailey
commented
Feb 18, 2025
| @@ -3193,7 +3193,7 @@ func (r *Relater) structuredTypeRelatedToWorker(source *Type, target *Type, repo | |||
| var originalErrorChain *ErrorChain | |||
| saveErrorState := r.getErrorState() | |||
| relateVariances := func(sourceTypeArguments []*Type, targetTypeArguments []*Type, variances []VarianceFlags, intersectionState IntersectionState) (Ternary, bool) { | |||
| if result := r.typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState); result != TernaryFalse { | |||
| if result = r.typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState); result != TernaryFalse { | |||
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This one is legitimately a bug.
sandersn
approved these changes
Feb 19, 2025
jakebailey
changed the title
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This is a version of #357 but with custom lint rule which uses a control flow graph to determine when variable shadowing could never cause a negative side effect (the shadowing cannot flow into any code that uses the shadowed/outer variable). This reduces the number of false positives, and in one instance actually found an extra shadow that the lint rule in #357 didn't catch due to this PR being stricter about closing over outer variables.
Perf testing shows that this lint rule does not have any negative performance impact to linting (I have found other places that cause it to be slow).