TypeScript References Code Lens Provider

[mjbvz]

Fixes #18054

Adds an initial references code lens provider implementation for JS and TS

Remaining work and issues:

• Add setting to disable this references code lens provider.
• Add some gating for TS version
• Support properties as well as methods
• Support access modifiers and getters and setters (added workaround, but I believe we also need a fix on TS side: TSServer 'references' only Works if Target Location is in property name  TypeScript#13309)
• Support classes and interfaces
• Support export const ...
• Support export function
• Fix public construtor() {...} - (needs TS: Find All References Does not Work For constructors with Access Modifiers TypeScript#13330)
• Default exports (needs TS: Find references doesn't work with default exports when importing with a different name TypeScript#11551)

We also need to investigate the perf impact of the code lens further. It will be opt in to start with

[mjbvz]

@jrieken What is the proper way to reject code lenses if resolving them fails? I tried using Promise.reject, but that leaves a bunch of ugly blank lines in the document:

[jrieken]

I am afraid you cannot. The idea is that the editor does shake while we resolve things, e.g in the first, hopefully quick, phase we create all the empty space which make the editor 'jump' and then in the second phase we fill in those holes. Two options

• know in the first phase which lenses you cannot fill in (this the very much preferred solution), or
• use the new API of being able to tell the editor your set of lenses has changed. Will cause jumping/flicker and still requires you know valid lenses in the first phase

So, actually you only have one option ;-) and that is to only advertise lenses where you are sure you can fill them in

[mjbvz]

I added a workaround for the TS issue. We still want the fix from TS (the same bug also impacts the find all references command) but this should unblock shipping a preview.

This feature is actually pretty neat:

[dbaeumer]

Very nice. One additional idea is to resolve the code lens even if it fails with a string like 'No references found' or 'Reference resolving failed' if it doesn't happen too often.

[mjbvz]

@dbaeumer Thanks.

There are a few cases where TS has an internal error when attempting to determine the references (such as for public constructor). In that case, we use the messageCould not determine references. I've opened a bug on TS for this: microsoft/TypeScript#13330