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Thank you for the report. Can you provide a link to the repo where you are seeing these issues? I appreciate the examples, but it is hard to understand them completely without the full context of the package.

Really, any piece of code will illustrate the problem. consider for example trying to pass in a func literal to something that expects an http.HandlerFunc, or this example:

	type fT struct { 
		F []string
	}

	f := fT{F: 

here, you won't get a []string{} as a completion suggestion.

But I built the original examples while working on https://github.com/globusdigital/feature-toggles (e.g.: https://github.com/globusdigital/feature-toggles/blob/master/storage/mongo.go#L85, and start typing s.client.Database( again)

Thanks for the link. We'll take a look.

/cc @muirdm

This is what I see (note the first two candidates):

What editor are you using and what do you see as your candidates? I'm guessing the problem is that you don't have snippets enabled. We recently changed literal completions to require the client to support snippets.

For your original issue, there is another problem where literal completions don't work for variadic function args. I think we can fix that.

At the very least, I would expect an empty string as one of the top suggestions.

The assumption is that typing the zero value for basic values is easy enough that you don't need a completion candidate.

The assumption is that typing the zero value for basic values is easy enough that you don't need a completion candidate.

For a string, yes. But for a struct, not so much. Unless that's also handled by these snippets you are talking about.

These are the suggestions if the field is a struct:

The first one is ok, but that is as far as the usefulness of these suggestions go. None of the other are even remotely useful as a suggestion at that cursor position

I'm using neovim 0.5 with the builtin lsp client here

Literal completions (e.g. []string{} or some.Struct{}) require the client to have snippets supported/enabled. I would see if you can enable snippets in your client. You may have to install a separate package - I'm not too familiar with all the different Vim flavors/clients. You can ask on the #vim channel on gophers slack .

@stamblerre we may want to reconsider disabling all literal completions when the client doesn't have snippets.

@muirdm
What about all the suggested completions (except the first two) from the second screenshot? I don't see any way how one can produce something of type bT with any of those suggestions

@stamblerre we may want to reconsider disabling all literal completions when the client doesn't have snippets.

@muirdm: I thought we had done that, or do you mean disabling the nil completion item in the first example?

What about all the suggested completions (except the first two) from the second screenshot? I don't see any way how one can produce something of type bT with any of those suggestions

This falls in the same category of literal completions, which are disabled if snippets are not supported by the client. @muirdm: Do you think we can come up with some best-effort literal completions that work without snippets?

Literal completions already have non-snippet versions. We disabled them in https://go-review.googlesource.com/c/tools/+/216299, but there was some confusion in that decision (I had a critical typo in the related issue where I voted for the wrong change).

Regarding all the junk candidates that couldn't possibly be useful, I think we can start filtering some of them out. I can make a separate issue for that.

Ah, I'm sorry I didn't realize that these were our non-snippet versions of the candidates. Maybe they could diverge further from the snippet versions like @myitcv suggested in the original bug (#36655):

What did you expect to see?

&protocol.SignatureHelpParams

What did you see instead?

&protocol.SignatureHelpParams{}

Since the only issue is having to backtrack with the cursor, maybe we could do &protocol.SignatureHelpParams{. Optionally we could try to use an additional edit to place the closing curly after the cursor, as @myitcv originally suggested.

Either works for me, though maybe we can start with just the opening brace if that's easier?

@muirdm

Optionally we could try to use an additional edit to place the closing curly after the cursor, as @myitcv originally suggested.

This would of course get my vote ;-)

I played around with the idea of emulating simple snippets using insert text and additional edits: https://go-review.googlesource.com/c/tools/+/222198

Honestly I don't think it is worth the extra code. I think we should either leave the current behavior and encourage people to use snippets, or revert to the previous behavior where, if you don't have snippets, you get []foo{}<> inserted and have to move one character to the left if you want to put stuff in the literal. That is no more keypresses than completing to []foo or []foo{ and having to type the curlie(s) yourself.

Change https://golang.org/cl/222199 mentions this issue: internal/lsp/source: fix literal completions in variadic args

Thanks for putting together a CL, @muirdm.

Honestly I don't think it is worth the extra code

Just to refresh on the reasons I think this is worthwhile:

• not all editors (read: at least Vim) have native snippet support, hence it relies on the user installing another plugin to add this support
• modal editors like Vim make the "just move the cursor one to the left" option really painful. This option also kind of defeats the point of LSP, because it feels like we're saying "we could do this on the server but you can just work around it".

The code changes didn't look that invasive to my untrained eye?

@muirdm

tbh, i'm absolutely fine as a user if i just have to move the cursor back a character after insertion. it's an insignificant price to pay to get those suggestions back, at least until the time that neovim gets support for snippets.

modal editors like Vim make the "just move the cursor one to the left" option really painful

Doesn't vim support the arrow keys these days? 😛

I'd rather the server not jump through hoops if the user can just install another package and get a better/fancier experience anyway. I know you @myitcv (and your users, and maybe other vim users) don't have that option yet, so I leave it up to @stamblerre.

I agree with @muirdm that the extra code isn't worth it (note that the CL is https://golang.org/cl/222198, not https://golang.org/cl/222199 in #37656 (comment) above). Thank you for doing this work, though! I really appreciate the investigation. If it's possible to install a Vim plugin that supports snippets, I would suggest that as the way forward.

@stamblerre
With this change, will gopls now suggest the literal completions even without snippet support?

I don't believe so. I think we will stick to the approach @muirdm suggested in #37656 (comment), which is to recommend that Vim users install another package that adds snippet support.