When an unstable method is autocompleted and no feature flag is present, add one

[SomeoneToIgnore]

In the project with nightly toolchain used, Some(22).ex<|> proposes expect_none method which is unstable currently.

But when I autocomplete it, I need to manually add the feature flag to enable the feature.
I would expect RA to add this flag automatically, if not added already.

[matklad]

Hard, as we first need to design the infra for answering the question "which unstable features are available".

[lnicola]

Maybe we could use the #[unstable] attribute on the item?

[p-avital]

Wasn't there an other issue recently that asked about "not offering to complete with unstable methods"?
Maybe "marking" the completions as unstable would be useful, seems like infra to handle unstableness has use cases either way.

[installgentoo]

So is there a way to hide unstable? Not autocompleting things that won't compile seems to me like a stable release gating feature, not just some minor thing.

[bjorn3]

Not that I know of. In any case it should be possible to autocomplete unstable things as you may be using nightly or be working in a part of the code gated behind nightly. I do agree that it would be useful to indicate that a method is unstable and deprioritize it though.

[lowr]

microsoft/language-server-protocol#1605 is needed to support this feature without limiting it to the crate-root files (which would be super weird from users' perspective). Or can we add another LSP extension until then? (I don't really know to what extent LSP extensions are capable of)