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Typeguard not working if checked against Exclude #49118
Description
Bug Report
🔎 Search Terms
typeguard exclude union
🕗 Version & Regression Information
v4.6.2
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about typeguards
⏯ Playground Link
Playground link with relevant code
💻 Code
type AAA = {
c: 0
b: 1
} | {
c: Exclude<number, 0>
x: 1
}
const a = {} as unknown as AAA
if (a.c !== 0) a.x🙁 Actual behavior
error
Property 'x' does not exist on type 'AAA'.
Property 'x' does not exist on type '{ c: 0; b: 1; }'.
🙂 Expected behavior
no error
Activity
MartinJohns commentedon May 15, 2022
The type
Exclude<number, 0>is exactly the same type asnumber. It does not do what you think it does. There is no way to represent a type "any number, except 0" in TypeScript. This would first require #29317.qwelias commentedon May 15, 2022
thanks, tho it's been open for 3+yrs now...
MartinJohns commentedon May 16, 2022
It's a fairly difficult issue to solve.