Typescript: Untyped function calls may not accept type arguments

[ghost]

The following code results in this error message:

mu.ts(52,10): error TS2347: Untyped function calls may not accept type arguments.

Why ?

class JsonRequest<T> {
    makePromise(request: https.RequestOptions): Promise<T> {
52:         return new Promise<T>(function(resolve, reject) {

[DanielRosenwasser]

Generally you use type arguments if you want to have type safety. What would it mean to give T as a type argument to Promise if it's typed as any? Just any? Sure, that's somewhat intuitionistic even if any doesn't have type parameters - but didn't you give a type argument to get type safety? So it makes little sense.

Maybe you can explain your use case better - why isn't Promise just typed?

[ghost]

The JsonRequest is created like this:

var categoryJsonRequest = new JsonRequest<CategoryResult>();

Therefore I expected that I can use the generic type parameter to create a Promise of the given type (CategoryResult in this case).

BTW: the definition in the d.ts file looks like this

declare class Promise<R> implements Thenable<R> {
    constructor(callback: (resolve : (result?: R) => void, reject: (error: any) => void) => void);

BTW: The module is imported like this:

var Promise = require('es6-promise').Promise;

[DanielRosenwasser]

Ah, my apologies, I misunderstood your question - I thought your definition of Promise was typed as any.

I'm not able to reproduce this issue - have you tried using the compiler from our release-1.4 or master branches?

[ghost]

Just checked it with the latest release from master (message TS6029: Version 1.4.0.0). Same result.

[DanielRosenwasser]

Could you share more code? Also, what promises library are you using?

[ghost]

I made a gist: https://gist.github.com/rogergl/e22afc63dafd8c2b0f6a

[DanielRosenwasser]

Replace

var Promise = require('es6-promise').Promise;

with

import es6PromiseLib = require('es6-promise');
var Promise = es6PromiseLib.Promise;

Let me know if that fixes your issue.

[ghost]

Yes it fixes my issue.

[DanielRosenwasser]

Great! As an explanation, the reason this happened is because we only try to fetch type information in the presence of an import directive, so the require on its own isn't sufficient.

[ghost]

Thanks a lot for the help and the explanation.