Disjoint enums and spread operator - false incompatibility

[wbecker]

Here is an example.

type Combined = | "AA" | false;

const x: Combined = "AA"; // ok
const y: Combined = false;  // ok

type OO = {foo?: Combined};

const o1: OO = {foo: "AA"}; // ok
const o2: OO = {foo: false}; // ok
o1.foo = o2.foo; // ok

const o3 = {foo: false, ...o1}; //error: This type is incompatible with boolean
const o4 = {foo: "AA", ...o1}; //error: This type is incompatible with boolean
const o5 = {...o1, ...o2}; // ok

In this case, the disjoint enum works fine on individual variables, and fine when assigned normally to an object.

However, when using the spread operator it can't figure out how to combine them, but only if you have explicitly set a value (o3 & o4). If you combine two objects using the spread operator without explicitly adding the value, it does work (o5)

[wbecker]

This may be a duplicate of #1488

[wbecker]

As suggested by o5, this does work however:

const o3 = {...{foo: false}, ...o1};
const o4 = {...{foo: "AA"}, ...o1};

[villesau]

This fixes the issue: #7298

[nmote]

This no longer errors in master