Inconsistent signatures, can't infer Promises

[Deleted user]

Given the following example functions:

class Foobar {}
function a() {
    return new Foobar();
}

function b(text = "hello") {
    return new Promise((resolve, reject) => resolve(text));
}

async function c(text = "hello") {
    return text;
}

And checking the results of textDocument/signatureHelp and textDocument/hover:

a signatureHelp: function a(): Foobar
a hover: function a(): Foobar

b signatureHelp: function b(text?: string): any
b hover: function b(text?: string): any

c signatureHelp: function c(text?: string): {}
c hover: function c(text?: string): Promise<string>

Shouldn't the type be inferred to be function b(text?: string): Promise<string> for all 4 cases of b and c? When a function returns a primitive or a class, the types are properly inferred. But it seems like it has trouble with the types of Promises and async functions. Is this a bug in the language server?

Visual Studio Code is at least able to infer Promise<any> for function b.

[Deleted user]

I have version 2.11.1 of the language server

[Felix Becker]

TypeScript can’t infer the type of the Promise from what you are passing to resolve. You need to explicitely declare the type of the Promise. There is a TSlint rule that enforces this btw.

Closing as it’s not a language server issue.

[Deleted user]

So then shouldn't it at least infer 'Promise<any>' rather than just 'any'. VSCode is able to do that.

And you haven't answered my question with respect to function 'c', either. I'm a little disappointed with your reply.

[Deleted user]

Also TSLint rules are not relevant here as in JavaScript we can't explicitly declare the type.