inlay hints cannot be shown just after openning project, edit is necessary to trigger the generation

[0x8f701]

Inlay hints isn't shown directly, I always need to do some modifications to make it works, the first fetchHints is always empty array as you can see from the following screenshot:

https://user-images.githubusercontent.com/33961674/87353897-f5853680-c55d-11ea-9fa4-cc8edc5eb664.png

I tested coc-rust-analyzer & vscode, they both have this issue

I believe it's because the analysis hasn't finished? Because after adding a sleep(30) in fetchHints, it can be correctly rendered.

So the first fetchHints has been called too early and RA just returned empty hints:

https://user-images.githubusercontent.com/33961674/87353897-f5853680-c55d-11ea-9fa4-cc8edc5eb664.png

[0x8f701]

See also: fannheyward/coc-rust-analyzer#317

[0x8f701]

If it's hard to detect when the analysis really finished, maybe we can just return back an error instead of empty hints? In this case the client can then launch retry

[Veetaha]

We can wait until workspace loaded progress end notification on the frontend, but in fact this indeed looks like a race condition in current impl such that it returns empty arrays from time to time.
@matklad do you think we can alleviate this race condition on the server side?
UPD: in fact I believe something like this also happens for semantic tokens (sometimes I need to do at least one edit to the document to make it display proper colors instead of unresolved reference color everywhere (same thing happens when you add mod declaration for a file, but you have it open in the editor, after adding the declaration you need to manually do an edit to refresh the highlights but this may be unrelated)

[matklad]

Yup, this is the same problem as with semantic tokens, pure pull model does not work here. I think I still believe that Dart's subscriptions are fundamentally better here than what LSP is trying to do:

https://htmlpreview.github.io/?https://github.com/dart-lang/sdk/blob/master/pkg/analysis_server/doc/api.html#request_analysis.setSubscriptions