Await does not work with interface extending Promise

[jsedlacek]

TypeScript Version: 2.1.4

Code

interface HelloPromise extends Promise<string> {}

function hello() : HelloPromise {
  return Promise.resolve('hello');
}

async function run() {
  await hello();
};

run();

Expected behavior: The code is compiled without errors.

Actual behavior: Following error is reported:

tsc -t es6 --strictNullChecks index.ts
index.ts(8,3): error TS1058: Operand for 'await' does not have a valid callable 'then' member.

You can find the repro code here:
https://github.com/jsedlacek/ts-promise-repro

[jsedlacek]

Note: This code works in typescript 2.0.4.

[jwbay]

Duplicate of #12292?

[mhegazy]

Fix should be in typescript@next later tonight. Please give it a try and let us know if you are still running into issues.

[jsedlacek]

Thanks, I can confirm that typescript@next fixes this issue.