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Spread arguments length check doesn't work with function overloads #23637
Description
TypeScript Version: 2.9.0-dev.20180422
Search Terms: spread, overload
Code
function foo(): void;
function foo(...args: {}[]): void {}
function bar(...args: {}[]) {
foo(...args);
}Expected behavior:
No Errors.
Actual behavior:
error TS2556: Expected 0 arguments, but got 1 or more.
If I just swap the order of the declarations of function foo it works.
Related Issues:
#20071 is the fix for excess spread operator check.
#21906 is very close to my issue, but not quite the same.
Activity
mhegazy commentedon Apr 24, 2018
The implementation signature is not considered part of the overloads for the method. in other words,
foohas one overload that takes no arguments.if you want to call the function with with variable number of arguments add a new overload:
bowenni commentedon Apr 24, 2018
Thanks for the quick reply! Adding a new overload solved the problem for me.
Would you consider
The implementation signature is not considered part of the overloads for the methodintended or bug? It feels counter intuitive that I have to explicitly declare a new overload even though I have an implementation already.AlCalzone commentedon Apr 25, 2018
Having the exposed overloads separate from the implementation allows to expose nice and cleanly typed overloads while having an ugly internal implementation signature that just exists to match all the “official” function signatures.
So definitely a feature IMO
typescript-bot commentedon May 9, 2018
Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.