Open
Description
Found from #55916.
Today if you try to write a generic constructor, captured type parameters fail to create a generic signature. Instead, the type parameter is effectively leaked and never instantiated.
/**
* @template T
*/
class C {
/**
* @overload
* @param {T} value
*/
/**
* @overload
* @param {T} first
* @param {T} second
*/
/**
* @param {T} first
* @param {T} [second]
*/
constructor(first, second) {
}
}
const x = new C(123);
// ~~~
// Argument of type 'number' is not assignable to parameter of type 'T'.
// 'T' could be instantiated with an arbitrary type which could be unrelated to 'number'.
const y = new C("hello", "world");
// ~~~~~~~
// Argument of type 'string' is not assignable to parameter of type 'T'.
// 'T' could be instantiated with an arbitrary type which could be unrelated to 'string'.The current-workaround is to write something like the following:
/**
* @template T
*/
class C {
/**
* @template T
* @overload
* @param {T} value
* @return {C<T>}
*/
/**
* @template T
* @overload
* @param {T} first
* @param {T} second
* @return {C<T>}
*/
/**
* @param {T} first
* @param {T} [second]
*/
constructor(first, second) {
}
}
const x = new C(123);
// ^?
const y = new C("hello", "world");
// ^?
const y = new C(123, "hello");
// ^?Notice that here, each @overload must declare its own type parameters and return type.
We should decide if this is actually how we want @overload to work in JSDoc on constructor declarations.