Bad inference for destructured object parameter with default value

[OliverJAsh]

TypeScript Version: 2.7.2

Search Terms: object literal parameter inference destructuring default value

Code

const fn1 = (options: { headers?: {} }) => {};
// No error as expected
fn1({ headers: { foo: 1 } });

const fn2 = ({ headers = {} }) => {};
// Unexpected error: Property 'foo' does not exist on type '{}'.
fn2({ headers: { foo: 1 } });

[RyanCavanaugh]

Regression from 2.6 -> 2.7

[ahejlsberg]

This is an issue exposed by #19513. We're not properly widening types in types implied by object destructuring patterns. Looks like a fairly simple fix.

[OliverJAsh]

Thank you!