Comparison targets are reversed (regression)

@RyanCavanaugh @weswigham @ahejlsberg Caused by #27697

TypeScript Version: 3.4.0-dev.20190222

Search Terms:

Code

https://github.com/falsandtru/spica/blob/v0.0.237/src/supervisor.legacy.ts#L49

Expected behavior:

pass

Actual behavior:

Argument of type 'this' is not assignable to parameter of type 'Supervisor<string, unknown, unknown, unknown>'.
  Type 'Supervisor<N, P, R, S>' is not assignable to type 'Supervisor<string, unknown, unknown, unknown>'.
    Type 'string' is not assignable to type 'N'.ts(2345)

Assignability checking must be N to string, not reverse.

Playground Link:

Related Issues:

[falsandtru]

Looks like good except an illegal ! at the second line.

[jack-williams]

@falsandtru Yep, sorry. What about this?

class Foo<T extends string> {
    private static instance: Foo<string>[];

    cast(_name: ([T] extends [string] ? string : string)) {
        
    }
    
    foobar() {
        Foo.instance.push(this);
    }
}