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Type narrowing not work with inferred function arguments #45671
Description
Bug Report
🔎 Search Terms
type narrow argument
🕗 Version & Regression Information
- This is the behavior in every version I tried
⏯ Playground Link
💻 Code
declare function wrapFunc(f: (ctx: Ctx) => void): void
declare function requireStr(s: string): void
interface Ctx {
throw(status: number): never;
}
async function f2(ctx: Ctx) {
let s: string | false = undefined as any
if (!s) ctx.throw(100)
requireStr(s)
}
wrapFunc(async function (ctx: Ctx) {
let s: string | false = undefined as any
if (!s) ctx.throw(100)
requireStr(s)
})
wrapFunc(async function (ctx) {
let s: string | false = undefined as any
if (!s) ctx.throw(100)
requireStr(s) // <-- Compile Error! here `s` is string | false
})
Activity
andrewbranch commentedon Sep 2, 2021
Documented as a limitation of #32695. #33622 considered calling this out as an error, but ultimately decided against it for never-returning functions. You can choose between the type annotation and simply writing
return ctx.throw(100).