Cannot mix both fixed and rest arguments using '.call' when using '--strictBindCallApply' #37834

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1. rbuckton commented on Apr 8, 2020

   

   Ron Buckton (rbuckton)

   on Apr 8, 2020

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   The bind error case is likely a design limitation until we can represent spreading a non-array-type in a tuple type, i.e. [T, ...U] (if U has an array or tuple type as a base constraint).

   We could possibly resolve the call error case by adding a few overloads.

   👍React with 👍1Reacted by Gonçalo Fernandes
2. rbuckton commented on Apr 8, 2020

   

   Ron Buckton (rbuckton)

   on Apr 8, 2020

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   The bind case could also be partially resolved by specifying a fixed set of unbound type arguments, i.e.:

   bind<T, A0, A extends any[], R>(
     this: (this: T, arg0: A0, ...args: A) => R,
     thisArg: T
   ): (arg0: A0, ...args: A) => R;

   This is similar to the existing bind<T, A0, A extends any[], R> overload, except that it passes on arg0 and allows us to have the fixed argument list.
3. rbuckton commented on Apr 8, 2020

   

   Ron Buckton (rbuckton)

   on Apr 8, 2020

   Last edited by rbuckton

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   Unfortunately, just adding overloads doesn't address this. I added these to call and ended up with cases that should be errors compiling successfully:

       call<T, A0, A extends any[], R>(this: (this: T, arg0: A0, ...args: A) => R, thisArg: T, arg0: A0, ...args: A): R;
       call<T, A0, A1, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, ...args: A): R;
       call<T, A0, A1, A2, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2, ...args: A): R;
       call<T, A0, A1, A2, A3, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3, ...args: A): R;

   From tests\cases\conformance\functions\strictBindCallApply1.ts:

   declare function foo(a: number, b: string): string;
   ...
   let c03 = foo.call(undefined, 10, "hello", 30);  // Error

   The above call reports an error without the overloads: error TS2554: Expected 3 arguments, but got 4., but with the overloads we infer a function type that has the excess argument A3 and foo is assignable to that type so we don't report an error.
4. Ryan Cavanaugh (RyanCavanaugh)

   added

   Needs InvestigationThis issue needs a team member to investigate its status.This issue needs a team member to investigate its status.

   on Jun 1, 2020
5. Ryan Cavanaugh (RyanCavanaugh)

   added this to the Backlog milestone on Jun 1, 2020