From: microsoft/vscode#25215

TypeScript Version: 2.3.1-insiders0420

Code

Using es2015.lib.d.ts:

function foo(x: Promise<boolean>) {}

foo(new Promise(() => true))

Expected behavior:
This compiles fine with TS 2.2.2 and with the older insiders 2.3.1 release.

Actual behavior:
With the current insiders, we get: message: 'Argument of type 'Promise<{}>' is not assignable to parameter of type 'Promise<boolean>'. Type '{}' is not assignable to type 'boolean'.'

This is causing upwards of 230 compiler errors in the vscode codebase

Possible related to #15104