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!. after ?. should be warned #35071

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!. after ?. should be warned#35071
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Awaiting More FeedbackThis means we'd like to hear from more people who would be helped by this featureSuggestionAn idea for TypeScript

Description

@falsandtru
falsandtru (falsandtru)
opened on Nov 13, 2019

This is an anti-pattern on the current type system. And the compiler must not do quick fix so. !. after ?. is simply replaceable with ?. and should do so.

TypeScript Version: 3.7.x-dev.20191105

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Code

document.querySelector('_')!.textContent!.split('') // old code
document.querySelector('_')?.textContent!.split('') ?? 0 // string[]
document.querySelector('_')?.textContent?.split('') ?? 0 // string[] | 0

Expected behavior:

document.querySelector('_')!.textContent!.split('') // old code
document.querySelector('_')?.textContent!.split('') ?? 0 // unsafe, warning
document.querySelector('_')?.textContent?.split('') ?? 0 // safe

Actual behavior:

document.querySelector('_')!.textContent!.split('') // old code
document.querySelector('_')?.textContent!.split('') ?? 0 // unsafe, no warning
document.querySelector('_')?.textContent?.split('') ?? 0 // safe

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  1. kitsonk commented on Nov 13, 2019

    @kitsonk
    Kitson Kelly (kitsonk)
    on Nov 13, 2019
    Contributor

    Isn't this a just linting rule? Whenever you use ! it is potentially unsafe. The compiler never warns, an error is an error.

  2. falsandtru commented on Nov 13, 2019

    @falsandtru
    falsandtru (falsandtru)
    on Nov 13, 2019
    ContributorAuthor

    When quick fix observes this rule, it is wasteful splitting.

  3. RyanCavanaugh commented on Nov 13, 2019

    @RyanCavanaugh
    Ryan Cavanaugh (RyanCavanaugh)
    on Nov 13, 2019
    Member

    falsandtru (@falsandtru) some discussion about what exactly is different between this and #35025 would be nice

  4. falsandtru commented on Nov 13, 2019

    @falsandtru
    falsandtru (falsandtru)
    on Nov 13, 2019
    ContributorAuthor

    This issue has meaning without adopting #35025 and meaningless if #35025 is adopted. So this issue and #35025 are in opposition. This is the definitive difference.

  5. Ryan Cavanaugh (RyanCavanaugh)
    added
    Awaiting More FeedbackThis means we'd like to hear from more people who would be helped by this feature
    SuggestionAn idea for TypeScript
    on Nov 13, 2019
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