lsp-csharp doesn't work with C# .net 6 projects when using csharp-ls as a language-server

[josteink]

Thank you for the bug report

• I am using the latest version of lsp-mode related packages.
• I checked FAQ and Troubleshooting sections
• You may also try reproduce the issue using clean environment using the following command

emacs -q -l lsp-start-plain.el

where lsp-start-plain.el can be downloaded here.

Bug description

The title pretty much says it all, but if that was all I realize I should be reporting this in csharp-ls instead of here 😄

The main problem seems to be that lsp-csharp actually provides 2 language-servers:

• One based on Omnisharp-Roslyn
• One based on csharp-ls ... which somehow wraps Omnisharp?

Of these two only csharp-ls is unable to run with .NET 6 projects.

So the solution is for the user to chose the Omnisharp server, and keep on working, right?

And here is the problem: The way lsp-csharp is implemented the csharp-ls language server "shadows" the Omnisharp-Roslyn language-server, making csharp-ls the only selectable/installable language-server option for C#.

A temporary workaround I have to work with .NET 6 so far is to:

• comment out all the csharp-ls code in lsp-csharp.el
• delete ~/.dotnet/tools/csharp-ls
• delete ~/.emacs.d/.cache/lsp/omnisharp-roslyn
• restart emacs
• install Omnisharp server when prompted

If we have 2 language servers for one language, it should IMO be possible for the user to chose which one he prefers, and right now it seems like that is not really possible.

CC: @razzmatazz

Steps to reproduce

sudo apt install dotnet-sdk-6.0
mkdir test
cd test
dotnet new console
emacs Program.cs

Observed:

• You are prompted to install csharp-ls language server (with no choice for other server)
• Language-server does not work

Expected behavior

If several language servers are available:

• be able to chose which one I want
• supplied language servers to work on current versions of .NET

Which Language Server did you use?

lsp-csharp with csharp-ls language server.

OS

Linux

Error callstack

No response

Anything else?

No response

[razzmatazz]

@josteink there is razzmatazz/csharp-language-server#3 issue reported by someone yesterday

will take a look later today/this week

as for csharp-ls -- this is my reimplementation of LSP server on top of roslyn (independent implementation from omnisharp-roslyn) -- I got tired trying to get people @ omnisharp-roslyn to merge my PRs and fixes and figured I could my own LSP server -- shouldn't be that hard huh.. and for most part it isn't that hard :D as LSP maps really nicely to Roslyn APIs. omnisharp-roslyn is way more complex and has long history, as it needs to support old protocol for vscode client and other things -- csharp-ls is much simpler

it already has some features omnisharp-roslyn doesn't, like go-to-definition in metadata

I think this should then be closed :)

[josteink]

I think closing is premature. You can see this issue is really 2 issues:

• error in csharp-ls (which should obviously be fixed in csharp-ls)
• lsp-csharp having 2 language-server definitions/implementations, but only 1 of them being selectable by the user (csharp-ls).

The latter is definitely an issue which should be fixed in lsp-csharp IMO.

[razzmatazz]

oh.. right

[yyoncho]

There is lsp-enabled-clients and lsp-disabled-clients which you can use for selecting what servers you want to run.

[yyoncho]

I believe there is nothing else here(please reopen if you disagree).

[josteink]

Not so much agreeing vs disagreeing, as much as I think lsp-mode should let me chose (interactively) what language server to use when there are several options.

Right now it seems it just defaults to the last one defined and forgets/disregards previously defined language servers.

As a user there's literally no way to know there are other options (which can be enabled/disabled through elisp), because only one option is shown.

If that user-experience could be improved, I for one would really appreciate it.

Is this a general problem for lsp-mode as a whole or an issue specific to lsp-csharp? I don't know. Wouldn't it be interesting to find out?

I know rust has the same thing with several language servers (rls vs rust-analyser). Does the same issue manifest itself there?

I know as a maintainer one may be overburdened with work, but still, just closing the issue seems a tad dismissive to me.

[razzmatazz]

@josteink I could not replicate your problem though..

(doom emacs + some stock version of emacs-lsp/lsp-mode)

I get omnisharp (as second selection item) and then, when I type "ENTER" it installs and runs properly for me..

LSP :: Download omnisharp started.                                                                                     
LSP :: Starting to download https://github.com/omnisharp/omnisharp-roslyn/releases/latest/download/omnisharp-linux-x64$
Contacting host: github.com:443                                                                                        
Wrote /home/bob/.emacs.d/.local/etc/lsp/omnisharp-roslyn/latest/omnisharp-roslyn.zip                                   
LSP :: Finished downloading /home/bob/.emacs.d/.local/etc/lsp/omnisharp-roslyn/latest/omnisharp-roslyn.zip...          
(Shell command succeeded with no output)                                                                               
LSP :: Server omnisharp downloaded, auto-starting in 1 buffers.                                                        
LSP :: Guessed project root is ~/src/csharp/csharp-test                                                                
LSP :: Connected to [omnisharp:1580164/starting].                                                                      
LSP :: omnisharp:1580164 initialized successfully in folders: (/home/bob/src/csharp/csharp-test)                       

you said something about "shadowing" of omnisharp server version, how does it manifest on your machine?

one thing we could do is mark "csharp-ls" as "experimental" on the server selection list, as it is not of that high quality as omnisharp-roslyn (even if it has other features that omnisharp lacks)

maybe we should change priority of the csharp-ls ? @yyoncho now we have "csharp-ls" with :priority -2 while "omnisharp" has priority: -1. Does this mean that omnisharp has "higher priority" or not? because you can see on my screenshot "omnisharp" goes as "second" option on the list..

[josteink]

Thanks for the feedback so far guys.

I’ll try to get a screenshot and a minimal POC for reproducing tomorrow, so we have something (more) concrete to work with.

I mean, if I had gotten both options like you did, I wouldn’t have posted a issue here 😅

[razzmatazz]

@yyoncho I will let myself reopen this as @josteink seems to be having an issue with having omnisharp listed for some reason; also can you reply to my question regarding how :priotity value should work on this comment:

• lsp-csharp doesn't work with C# .net 6 projects when using csharp-ls as a language-server #3198 (comment)

[yyoncho]

@josteink this was discussed at the beginning of the project.

1. All lsp(vscode, theia, vim, etc) clients automatically select the language server.
2. We have documented how to select a different server from the one with the highest priority in the FAQ section.

For sure if we ask the user to pick a server each time you open a project will bring tons of issue reports until we turn that off which again will narrow down to using lsp-enabled-clients/lsp-disabled-clients.

I know as a maintainer one may be overburdened with work, but still, just closing the issue seems a tad dismissive to me.

I thought that I have answered your question.

[yyoncho]

@razzmatazz

one thing we could do is mark "csharp-ls" as "experimental" on the server selection list, as it is not of that high quality as omnisharp-roslyn (even if it has other features that omnisharp lacks)

maybe we should change priority of the csharp-ls ? @yyoncho now we have "csharp-ls" with :priority -2 while "omnisharp" has priority: -1. Does this mean that omnisharp has "higher priority" or not? because you can see on my screenshot "omnisharp" goes as "second" option on the list..

I think that it is up to you. About the order of the servers in the list - we should do sorting by priority. I believe now the sorting is random. We may add a flag to the client :recommended which to list in that dialog.

[razzmatazz]

@razzmatazz

one thing we could do is mark "csharp-ls" as "experimental" on the server selection list, as it is not of that high quality as omnisharp-roslyn (even if it has other features that omnisharp lacks)
maybe we should change priority of the csharp-ls ? @yyoncho now we have "csharp-ls" with :priority -2 while "omnisharp" has priority: -1. Does this mean that omnisharp has "higher priority" or not? because you can see on my screenshot "omnisharp" goes as "second" option on the list..

I think that it is up to you. About the order of the servers in the list - we should do sorting by priority. I believe now the sorting is random. We may add a flag to the client :recommended which to list in that dialog.

so :priority does not mean anything now, right?

[razzmatazz]

@josteink now I am wondering, is your problem that you:
(a) are not able to select a server when you have one/more of them installed, or
(b) are not able to select a server to install when you have none installed?

[yyoncho]

@razzmatazz no, priority atm is strictly for selecting which LS to run when both are present. https://emacs-lsp.github.io/lsp-mode/page/faq/#i-have-multiple-language-servers-registered-for-language-foo-which-one-will-be-used-when-opening-a-project

[razzmatazz]

btw, @josteink I have just released csharp-ls 0.1.6 that has support for net6.0 projects too (among other improvements)

[josteink]

No idea why, but seeing as:

1. csharp-ls now works with .net 6.0, and
2. I can no longer reproduce the issue (that is lsp-mode now suggests both language-servers when none installed)...

I really think it's fully OK to close this issue.

Not sure what happened here or why, but sorry for wasting your time. I'll try to make sure it doesn't happen again 😄