Interfaces that extend imported interfaces don't get extended fields

[rictic]

Consider a project like:

// base.ts
export interface Checked {
  checked: boolean;
}

// main.ts
import {Checked} from './base';

interface CheckableElement extends HTMLElement, Checked {}

declare global {
  interface HTMLElementTagNameMap {
    'checkable-element': CheckableElement;
  }
}

web-component-analyzer appears not to know that <checkable-element> has a .checked property. The issue seems to be specific to interfaces that extend imported interfaces. Specifically, I checked these cases:

• ✅class extending another class declared in the same file
• ✅class extending another class imported from another file
• ✅interface extending an interface declared in the same file
• ❌interface extending an interface imported from another file

Standalone repro at https://github.com/rictic/repro-wca-import-interface-issue

[runem]

Thank you so much for this issue and the repro. I have now fixed the problem and added test cases to this file so it won't happen again 🎉

[rictic]

Nice! I can confirm that that fixes the bug here.

I think there's something still up with the original code that I reduced this down from, which is that the plugin can't find the checked property on <paper-checkbox>. I'm working on coming up with a minimal repro now.