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Allow bitwise test on undefined #22230
Description
TypeScript Version: 2.8.0-dev.20180228
Search Terms: undefined strictNullChecks bitwise and or
(ref: #22088 (comment))
Code
const enum Flags { A = 2 ** 1, B = 2 ** 2 }
function f(flags?: Flags) {
if (flags & Flags.B) {
}
}Expected behavior:
No error. & and | work well on undefined values: undefined | 2 is 2, undefined & 2 is 0. Contrast with undefined + 2 which is NaN.
Actual behavior:
src/a.ts(3,9): error TS2532: Object is possibly 'undefined'.
Activity
RyanCavanaugh commentedon Aug 7, 2018
It's possible
0andundefinedare intended to have the same semantics in this function, but we really don't know. Arguably the signature should beflags: Flags = 0if that's the case