Accessing protected property on this-type outside of class body doesn't work for generic classes

[ajafff]

TypeScript Version: 3.9.0-dev.20200220

Search Terms:

Code

class Regular {
    protected foo = 1;
}

function regular(this: Regular) {
    this.foo; // works
}

class Generic<T> {
    protected foo = 1;
}

function generic(this: Generic<unknown>) {
    this.foo; // error
}

Expected behavior:

There should be no difference between generic and non-generic classes. Both functions should be allowed to access this.foo.

Actual behavior:

Property 'foo' is protected and only accessible through an instance of class 'Generic<unknown>'.(2446)

Playground Link: http://www.typescriptlang.org/play/?ts=3.9.0-dev.20200220#code/MYGwhgzhAEBKCmBzAruATtA3gKGn6ADmgPYAu8w5AJtAGbHHQC80AjANzYC+22tyAO0oBLYgOhokqMGgAUpABbCIALjhT0ASiy58i5QDp6xdtAD0Z6AHdiaANYRuvUJBgBxeAPhphwADwAKgB8OviEJOSU8DTGzGycPHyCImLQiJ7evvJKqtAeXj7+gnYCxFYCQdo4YfoQRgymFtDeJGjcQA

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