Microsoft/TypeScript
Ver no GitHubOverloaded function args not inferred correctly
Open
#54.539 aberto em 5 de jun. de 2023
Domain: check: Type InferenceHelp WantedPossible Improvement
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Description
Bug Report
🔎 Search Terms
overload functions
🕗 Version & Regression Information
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about overloading and different function arguments behavior
⏯ Playground Link
Playground link with relevant code
💻 Code
function a1(arg1: unknown): 1;
function a1(arg1: unknown, arg2: unknown): 2;
function a1(...args: ([arg1: unknown] | [arg1: unknown, arg2: unknown])): 1 | 2 {
return args.length;
}
const b1: typeof a1 = function f1(...args) {
return a1(...args);
}
even simpler is using an interface
interface a1 {
(arg1: unknown): 1;
(arg1: unknown, arg2: unknown): 2;
}
// errors
const b1: a1 = function f1(...args) {
return args.length;
}
🙁 Actual behavior
Error: Target signature provides too few arguments. Expected 2 or more, but got one., given the single signature of b1 above is variadic, and in fact matches the implementation signature of a1, one would assume the two functions are equivalent (from a signature perspective)
🙂 Expected behavior
The type of args in b1 should be inferred as the union of all overloads of a1 since it is the only way the variadic args would satisfy the assigned typeof a1 requirement.