TypeScript debugger (Watch) incorrectly gives "Uncaught ReferenceError: <class> is not defined" for extern classes in another file

[sean-mcmanus]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.59.0
• OS Version: Windows.

Steps to Reproduce:

1. Use test.ts with

import {
    Task, TaskProvider
} from 'vscode';

export class CppBuildTaskProvider2 implements TaskProvider {
    static CppBuildScriptType: string = 'cppbuild';

    public async provideTasks(): Promise<Task[] | undefined> {
        return undefined;
    }

    public resolveTask(_task: Task): Task | undefined {
        return undefined;
    }
}

2. Debug an existing extension that references the CppBuildTaskProvider2.CppBuildScriptType and add that to the Watch window, e.g.

import { CppBuildTaskProvider2 } from './test';

export function activate(context: vscode.ExtensionContext) {
    let errMsg: string = CppBuildTaskProvider2.CppBuildScriptType;
}

Bug: See the screenshot: The debugger (Watch window) gives Uncaught ReferenceError: CppBuildTaskProvider2 is not defined.

Note that the value can be seen via assigning it to a local variable.

[connor4312]

This is because TypeScript doesn't expose that as a local and instead rewrites the import, for instance if you look at the compiled code:

It's a feature request on TS to emit a names mapping for imports microsoft/TypeScript#9627