Flow: Hang for override method with rest parameters that recursively calls itself

[andy-ms]

// @flow

class A {
    f(x: any, ...args: any[]) {}
}

class B extends A {
    f(x, ...args) {
      if (x.y) {
        this.f(x.y, ...args);
      }
    }
}

Type checking never terminates.

[philikon]

Dupe of #3370?

[philikon]

cc @gabelevi

[philikon]

Yep, and much like I pointed out in #3370, if you declare the rest arg types on B.prototype.f, the problem goes away:

class B extends A {
    f(x, ...args: any[]) {
      if (x.y) {
        this.f(x.y, ...args);
      }
    }
}

[gabelevi]

Ok, I have a fix! I'll try to get it reviewed and cherry picked into v0.42!