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Error for explicit return type with no return statements is misleading #53559
Description
function foo(): string {
}Currently in nightly, you'll get the error
error TS2847: A function whose declared type is neither 'undefined', 'void', nor 'any' must return a value.
But this error message is inaccurate, as you can now annotate with unknown.
Activity
fatcerberus commentedon Mar 28, 2023
In fact can't you now annotate with any type which is inhabited by
undefined?DanielRosenwasser commentedon Mar 28, 2023
Pretty much, which means that if you wrote
that'll be okay in TypeScript 5.1. You'll need to enable
--noImplicitReturnsto catch something like that.RyanCavanaugh commentedon Sep 19, 2026
Fixed by PR #53607. In 5.1.0-dev.20230401,
(): unknown => {}was accepted while TS2355 said onlyvoidandanycould omit a return. Starting with 5.1.0-dev.20230402, both thestringandunknownforms report TS2355, whose text correctly includesundefined,void, andany. The same result is present in TypeScript 6.0.3 and the current native compiler.