Bug? with "never" type

[bjornbacklund]

TypeScript Version: 2.1.4.0

class C
{
	public f1() {
		return 1;
	}

	public f2()
	{
		if (this instanceof Sub)
			return 2;

		return this.f1(); // Does not compile: error "f1 does not exist on type never"
	}
}

class Sub extends C
{

}

Expected behavior:
Compile without error

Actual behavior:
Error "f1 does not exist on type never"

[akarzazi]

instance of operator is out of order in TypeScript.
It uses shape comparison.

You can bypass it by adding a fake property:

class C
{
	public f1() {
		return 1;
	}

	public f2()
	{
		if (this instanceof Sub)
			return 2;

		return this.f1(); // ok
	}
}

class Sub extends C
{
    private _prop: string;
}

This issue is similar to : #11664