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NonNullable doesn't work on mapped types instantiated with null/undefinedΒ #57151

Closed as not planned
Closed as not planned
NonNullable doesn't work on mapped types instantiated with null/undefined#57151
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ahejlsberg
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Design LimitationConstraints of the existing architecture prevent this from being fixed

Description

@Andarist
Mateusz BurzyΕ„ski (Andarist)
opened on Jan 24, 2024

πŸ”Ž Search Terms

mapped nonnullable empty object null undefined instantiation

πŸ•— Version & Regression Information

⏯ Playground Link

https://www.staging-typescript.org/play?ts=5.4.0-dev.20240124#code/C4TwDgpgBAYg9nAPAFQHxQLxQHJwHbYCuANsQIYBGxEiA3lANoDSUAlnlANYQhwBmUZAF0AXIOZCoAX1QBYAFALQkKACUIAZxLBMsBIjwliqIA

πŸ’» Code

type Foo<T> = NonNullable<{ [K in keyof T]: T[K] }>

type Result = Foo<null>

πŸ™ Actual behavior

Result is of type null

πŸ™‚ Expected behavior

Result should be of type never

Additional information about the issue

This likely gets closed as a design limitation like the one here: #56644

Activity

  1. Ryan Cavanaugh (RyanCavanaugh)
    added
    Needs InvestigationThis issue needs a team member to investigate its status.
    on Feb 1, 2024
  2. Ryan Cavanaugh (RyanCavanaugh)
    assigned
    Anders Hejlsberg (ahejlsberg)
    on Feb 1, 2024

  3. ahejlsberg commented on Mar 6, 2024

    @ahejlsberg
    Anders Hejlsberg (ahejlsberg)
    on Mar 6, 2024
    Member

    This likely gets closed as a design limitation like the one here: #56644

    That is indeed what I'm going to do. πŸ˜„

  4. Anders Hejlsberg (ahejlsberg)
    added
    Design LimitationConstraints of the existing architecture prevent this from being fixed
    and removed
    Needs InvestigationThis issue needs a team member to investigate its status.
    on Mar 6, 2024

  5. typescript-bot commented on Mar 9, 2024

    @typescript-bot
    TypeScript Bot (typescript-bot)
    on Mar 9, 2024
    Contributor

    This issue has been marked as "Design Limitation" and has seen no recent activity. It has been automatically closed for house-keeping purposes.

  6. TypeScript Bot (typescript-bot)
    closed this as not plannedon Mar 9, 2024
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