Intellisense doesn't work with constant function parameters

[egamma]

From @startrekdude on April 5, 2016 23:49

• VSCode Version: 0.10.11
• OS Version: Windows 10

Steps to Reproduce:

files.zip

1. Create a file called SomeAPI.js with the following content:

var SomeAPI = (function () {
   "use strict";  
    var exports = {};

    exports.sayHello = function (name) {
        alert("Hello, " + name);
    }

    return exports;
})();

1. Create a file called SomeAPI.d.ts with the following content:

declare namespace SomeAPI {
    function sayHello (name: string) => void;
}

1. Create a file called app.js with the following content:

/// <reference path="./SomeAPI.d.ts"/>
(function (SomeAPI) {
    "use strict";

    var hello = function () {
        SomeAPI.sayHello(document.body); // Oops! No Intellisense!
    }

    document.addEventListener("DOMContentLoaded", hello);
})(SomeAPI); // This one works

1. Mouse over the line where it says "SomeAPI.sayHello" (in app.js).

Observed Behaviour:
Visual Studio Code's Intellisense informs the user that SomeAPI is of the any type, as is it's child sayHello.

Expected Behaviour:
Visual Studio Code informs the user that SomeAPI is a namespace and that sayHello is a function that takes a string.

Why this bug is important to fix:
Immediately-Invoked Function Expressions were a common way of doing modules and scoping before ES6's (awesome) import statements. There is a lot of legacy code that still uses them.

Copied from original issue: microsoft/vscode#4990

[egamma]

Moving to TypeScript for investigation

[DanielRosenwasser]

@startrekdude your .d.ts file seems incorreclty authored. Did you mean the following?

declare namespace SomeAPI {
    function sayHello(name: string): void;
}

[startrekdude]

Indeed. 😄
Here's an updated zip file: files.zip

[michaelmesser]

Sadly the TS team has decided not to add this feature. See #4142 and #7601.

[DanielRosenwasser]

Reopened #4142.