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NoInfer and overloaded function argument inferenceΒ #57873

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Closed as not planned
NoInfer and overloaded function argument inference#57873
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Description

@kevinresol
Kevin Leung (kevinresol)
opened on Mar 21, 2024

πŸ”Ž Search Terms

NoInfer, overload

πŸ•— Version & Regression Information

Version 5.4.3

  • I was unable to test this on prior versions because this is a new feature

⏯ Playground Link

https://www.typescriptlang.org/play?#code/CYUwxgNghgTiAEAzArgOzAFwJYHtXwAcYdhkwQAKRALngDkcBJVREGAHgoEp4BeAPngA3HFmD8utbn0EixAbgBQoSLAQp02PIWKly7AIL8qtBs1YcKsAOa0DPAcNHjJ8KzFvx7MpwsWKwPABnDHgADykHWWc+HRIySmlHAEYuJUDUEPgATykbWhCYLFRrKN9gWKJ48goKITLUpSA

πŸ’» Code

declare function produce(f: NoInfer<() => void>): () => void;
declare function produce<A>(f: NoInfer<(arg: A) => void>): (arg: A) => void;

const x: () => void = produce(() => 1); // works
const y: (arg: string) => void = produce((v) => 1); // Parameter 'v' implicitly has an 'any' type.

πŸ™ Actual behavior

Because const y is explicitly typed and thanks to the new utility NoInfer type, the compiler is able to figure out (from the return type) it is calling the produce<string>() overload. (Without NoInfer it would just be produce<any>()).

However, apparently it does not apply this knowledge to the function parameter f and thus the non type-hinted argument v is inferred as any

Screenshot 2024-03-21 at 12 04 31

πŸ™‚ Expected behavior

Since the compiler already knows f is of type NoInfer<(arg:string)=>void> it should be able to infer the lambda argument v to be of string type.

Screenshot 2024-03-21 at 12 13 46

Additional information about the issue

No response

Activity

  1. Andarist commented on Mar 21, 2024

    @Andarist
    Mateusz BurzyΕ„ski (Andarist)
    on Mar 21, 2024
    Contributor

    This isn't related to NoInfer as this doesn't assign the correct contextual parameter here either:

    declare function produce(f: () => void): () => void;
declare function produce<A>(f: (arg: A) => void): (arg: A) => void;
const y: (arg: string) => void = produce((v) => 1);

    There is a good chance that this PR might solve your issue: #57421

  2. Andarist commented on Mar 21, 2024

    @Andarist
    Mateusz BurzyΕ„ski (Andarist)
    on Mar 21, 2024
    Contributor

    Since Ryan Cavanaugh (@RyanCavanaugh) has prepared a playground for that mentioned PR (thanks!) we can now quickly confirm that it fixes this issue: TS playground

  3. Ryan Cavanaugh (RyanCavanaugh)
    added
    DuplicateAn existing issue was already created
    on Mar 22, 2024

  4. typescript-bot commented on Mar 25, 2024

    @typescript-bot
    TypeScript Bot (typescript-bot)
    on Mar 25, 2024
    Contributor

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

  5. TypeScript Bot (typescript-bot)
    closed this as not plannedon Mar 25, 2024
  6. microsoft
    locked as resolved and limited conversation to collaborators on Oct 22, 2025
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