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awaiting a Promise recasts top variable to initial type #19918
Description
TypeScript Version: 2.6.1, 2.7.0-dev.20171110
function test(a: boolean): false | Date {
if (a) {
return new Date();
}
return false;
}
async function test2() {
let b = test(true);
if (!b) {
b = new Date();
}
await Promise.all([]).then(() => {
b.getDate(); //Should compile.
})
}Expected behavior:
Should compile
Actual behavior:
Throws with Property 'getDate' does not exist on type 'true'.
This can be reproduced with any return type and even when type inference is used.
Activity
aluanhaddad commentedon Nov 10, 2017
Likely duplicate of #13180. Also, see #9998 for detailed commentary and discussion.
Note: this is not related to promises.
Simple fix:
bondz commentedon Nov 10, 2017
Thanks Aluan Haddad (@aluanhaddad). The simple fix works and looks like #9998 should cover this. Closing this ticket.