rest parameter not inferred as tuple from contextual type

[ajafff]

TypeScript Version: 3.0.0-dev.20180628

Search Terms:

Code

declare function take(cb: (a: number, b: string) => void): void;

/*1*/ (function foo(...rest){}(1, ''));
/*2*/ take(function(...rest){});

Expected behavior:

In both functions rest should be inferred as [number, string].

Actual behavior:

1: rest in IIFE is inferred as (string | number)[].
2: rest is inferred as any[] and emits implicit any error.

Related Issues:

[ahejlsberg]

Agreed, we should infer a tuple type in both cases above.