Object.assign({}) seems to always return a type any

TypeScript Version: 3.3.0-dev.20190110

Search Terms: Object.assign

Code

function foo(): {foo: string} {
    return Object.assign({});
}

Interestingly the code:

function bar(): {bar: string} {
    return Object.assign({}, {bar: 1});
}

does report the expected error

Expected behavior: TypeScript should report an error because the type returned by return Object.assign({}); does not mach {foo: string} but instead the type any is assumed.

Actual behavior: No error is shown

Playground Link: https://www.typescriptlang.org/play/index.html#src=function%20foo()%3A%20%7Bfoo%3A%20string%7D%20%7B%0D%0A%20%20%20%20return%20Object.assign(%7B%7D)%3B%0D%0A%7D%0D%0A

Related Issues: no

Start by reproducing the reported Object.assign example in the linked TypeScript Playground using the issue's TypeScript version and current nightly build. Trace how the compiler types Object.assign({}) and add a regression test that verifies the return is rejected when it does not satisfy {foo: string}.