Missing properties quickfix does not handle generic parameters

[hpx7]

Bug Report

🔎 Search Terms

quickfix missing properties generic parameter

🕗 Version & Regression Information

The quickfix was added in #44576 (cc @a-tarasyuk) but it doesn't appear to handle generic parameters.

💻 Code

interface Foo<T> {
  foo(): T;
}
const x: Foo<string> = {};

🙁 Actual behavior

The following is generated by the quickfix:

interface Foo<T> {
  foo(): T;
}
const x: Foo<string> = {
  foo: function (): T { // <-- this is wrong
    throw new Error("Function not implemented.");
  }
};

🙂 Expected behavior

I would expect to see string instead of T:

interface Foo<T> {
  foo(): T;
}
const x: Foo<string> = {
  foo: function (): string {
    throw new Error("Function not implemented.");
  }
};

[komyg]

Hey @RyanCavanaugh, I would like to help on this bug. Could you assign this issue to me?

[komyg]

Hey @RyanCavanaugh, it seems that this problem is already fixed in the nightly version of Typescript.

I've run a test in the playground and got the correct result: https://www.typescriptlang.org/play?ts=4.6.0-dev.20220116#code/JYOwLgpgTgZghgYwgAgGIHt0B4AqA+ZAbwFgAoZZGTACgEoAuZHAbjIF8yF0QBnMZAB6MM2PlFABzAgF4iZKukYwAriARhg3OozGS5pMAAso6AO7IQEcwFEoJqNQBEqVes0gL6fsAC2ABwAbCB8IcAgAEwA6R1pWUg545iA

I've opened a PR anyway, with an extra unit test for this case.