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Cannot mix both fixed and rest arguments using '.call' when using '--strictBindCallApply' #37834
Description
Activity
The
binderror case is likely a design limitation until we can represent spreading a non-array-type in a tuple type, i.e.[T, ...U](ifUhas an array or tuple type as a base constraint).We could possibly resolve the
callerror case by adding a few overloads.Reacted by Gonçalo FernandesThe
bindcase 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 onarg0and allows us to have the fixed argument list.Unfortunately, just adding overloads doesn't address this. I added these to
calland 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 argumentA3andfoois assignable to that type so we don't report an error.
TypeScript Version: 3.9.0-dev.20200328
Search Terms: strict call rest arguments
Code
Expected behavior:
The 2nd and 3rd cases above should be ok
Actual behavior:
The 2nd and 3rd cases above report errors.
Playground Link: Playground
Related Issues: