Advertise code action support

[YaLTeR]

Fixes #1037

[YaLTeR]

Hm, even though some code actions do show this way, they show without the rust-analyzer:

and I'm not sure I'm seeing all of actions I'm supposed to see. Not sure why.

[martskins]

Haven't looked too much into this, but it seems to me like command based actions have been removed now in rust-analyzer (https://github.com/rust-analyzer/rust-analyzer/pull/4494/files#diff-cb373ef102a169ef5e1af6f370fd21ccL718) and they seem to now use a different struct for the CodeActions, it would be nice to get the payload of the response from rust-analyzer and maybe check that it correctly deserializes to a lsp_types::CodeActionOrCommand.

On another note, you might want to rebase this to dev and change the target branch to it as well, as per this. There are some changes around code actions in ranges there that might be worth testing too.

[YaLTeR]

I rebased my changes onto dev and I see two issues:

1. LanguageClient_textDocument_codeAction() is broken (only the # version works).
2. For some reason on my vimrc the code actions take several seconds to actually apply and, strangely enough, also several seconds to undo with a u for large files (like src/language_server_protocol.rs). This was not the case when based on the next branch and this is also not the case with min-vimrc. I've no idea what causes this, any help?

Visual code actions seem to work fine.

[martskins]

About the first issue, I think it's because LanguageClient_textDocument_codeAction calls this:
call('LanguageClient#textDocument_codeAction', 'n', a:000), but it really should be calling this call('LanguageClient#textDocument_codeAction', a:000). (Note there's one parameater less there). I can raise a PR to fix this but if you are comfortable including that in this PR I say go for it.

The second issue I could not reproduce, checked out your PR and tried with LanguageClient-neovim 's code base and both visual and single line code actions show and apply in a very short time.

PS: remember to also change the target branch of the PR

[YaLTeR]

About the first issue, I think it's because LanguageClient_textDocument_codeAction calls this:
call('LanguageClient#textDocument_codeAction', 'n', a:000), but it really should be calling this call('LanguageClient#textDocument_codeAction', a:000). (Note there's one parameater less there). I can raise a PR to fix this but if you are comfortable including that in this PR I say go for it.

Could you make a separate PR please?

The second issue I could not reproduce, checked out your PR and tried with LanguageClient-neovim 's code base and both visual and single line code actions show and apply in a very short time.

Yeah, I'll check the profile log to see what causes it.

PS: remember to also change the target branch of the PR

Oh, right, thanks.

[martskins]

Sure, opened #1039 to fix that.

[YaLTeR]

I found how to reproduce the hang issue: set foldmethod=syntax. All these seconds it seems to spend recomputing fold and syntax information.

But "good" news is that I was wrong and it is also present on the next branch, so it's not a new issue.

[YaLTeR]

I pushed a fix for the empty string action kind, I think the PR is good to merge now.

[autozimu]

Thanks!