Suggest: auto-import often not working

[bpasero]

I very often have to manually import a type because suggest was not fast enough to do the auto import. I feel this happens more for me in web than in desktop:

I am always picking the suggestion fast enough that I end up just with the word but not the auto import.

[bpasero]

Slightly related: I often see something similar when I invoke quick fix on a missing type. At first I get no help and then trying again I get the advice to add the import.

[mjbvz]

@jrieken The root cause of this issue is that resolveCompletionItem may not complete before VS Code applies the completion. We've discussed this in the past but here are some of the issues I ran into while working around this item:

• It is difficult to tell whether VS Code has applied the full completion item or not.

  If VS Code has fully resolved the completion, the provider does not need to do anything. However there are cases like the one Ben was hitting where VS Code applies a completion before it has been fully resolved. In those cases, need to do extra work to manually apply the rest of the completion once it resolves.

  However I cannot simply to see if resolveCompletionItem has been called since VS Code may accept the completion and apply it before resolveCompletionItem returns. You also cannot check at the end of resolveCompletionItem, because VS Code may apply the completion before the results get back to the main thread.

• resolveCompletionItem is canceled in cases where the suggestion is accepted but resolve has not completed.

  This makes sense, but it meant that I had to use my own cancellation token when making the request to TypeScript. I need to do because the following can happen:

  1. start resolveCompletionItem()
  2. resolveCompletionItem awaits TS server
  3. The completion is accepted and resolveCompletionItem is canceled (along with the call to TS Server)
  4. But to make sure we properly apply the completion, I have custom TS completion items that apply additional edits for auto imports in a command. This command needs the results of the call to the TypeScript server from resolveCompletionItem to apply auto import.

  My workaround was to implement a custom cancellation token source that counts the number of callers who may need the response from TS server (it also uses a short timeout before actually cancelling the request).

I think my solution works, but it's quite ugly. Ideally TypeScript could eagerly returns all of the information we need to implement auto-imports, although they had concerns about how long that would take to compute and send over

[jrieken]

The completion is accepted and resolveCompletionItem is canceled (along with the call to TS Server)

This is arguably a bug. We shouldn't do that when we have explicitly called resolve during insert.

It is difficult to tell whether VS Code has applied the full completion item or not.

I am not quite sure why you need to know that. There should be an editor guarantee that resolve is only called once and the provider should resolve the item independent of the editor state. Tho, that's the ideal view but IDK how the reality of a provider is. What am I missing?

[bpasero]

Still unpleasant in web selfhost, I type and even though I get the auto import suggested, doing quick fix does not work until I press it 3 times: