Repository navigation
tsc 3.6.3: Promise.all breaks with some union type #33562
Description
TypeScript Version: 3.6.3
Search Terms: promise all
Code
type MaybePromise<T> = T | Promise<T> | PromiseLike<T>
function MaybePromise<T>(value: T): MaybePromise<T> {
return Promise.resolve(value)
}
async function main() {
let aaa: number
let bbb: string
[
aaa,
bbb,
] = await Promise.all([
MaybePromise(1),
MaybePromise('2'),
MaybePromise(true),
])
}tsconfig:
{
"compilerOptions": {
"strict": true,
"target": "es5",
"module": "commonjs",
"lib": [
"es6"
]
}
Expected behavior:
Code should compile without errors.
Actual behavior:
Error:
test.ts:11:9 - error TS2322: Type 'number | Promise<1>' is not assignable to type 'number'.
Type 'Promise<1>' is not assignable to type 'number'.
test.ts:12:9 - error TS2322: Type 'string | Promise<"2">' is not assignable to type 'string'.
Type 'Promise<"2">' is not assignable to type 'string'.
Code compiles well with 3.5.3, but not 3.6.3 nor 3.7.0-dev.20190922.
Playground Link:
Weirdly enough, on the playground the return value of Promise.all is not a tuple but a list.
Related Issues:
Activity
paul-marechal commentedon Sep 23, 2019
Encountered this issue while updating tsc, will stay on 3.5.3 until this is resolved :)
sandersn commentedon Oct 1, 2019
#33559 is only in 3.7, so is probably not related.