Gitpod: C/C++ Language Server doesn't work well for a C project

[jankeromnes]

A user reported this on Twitter:

I am trying to make my simple C library use intellisense in gitpod properly but have not been successful. If you have time, could you take a look too? I'd really appreciate it. Here is a link to the github: https://github.com/sirspot/ACR

I did a lot more reading about how gitpod works and I wonder if this is actually a limitation of their vscode extension support. The actual editor seems to find the files and can switch between source and headers just fine. Only the intellisense ext seems to have a problem.

Good news, it works perfectly if I open the command list and turn OFF the language server 😂 I even got a build task and debug to work 👍
This is going to be fun!

I find it a bit worrying that you have to turn off the Language Server in order to get a good C development experience. I'm opening this issue so that we can further investigate these issues.

[sirspot]

To reproduce:

1. Start with language server on
   

1. Turn off language server
   

2. Enjoy the ide's ability to lookup enum values and other names across files
   

[jankeromnes]

I notice that the project is installing the ms-vscode.cpptools VS Code extension:

https://github.com/sirspot/ACR/blob/bfed48fbc85215babb76efdad3ae0e83e4a98875/.gitpod.yml#L6-L8

However, Gitpod (and Theia) already come with a C/C++ language server extension: https://github.com/eclipse-theia/theia-cpp-extensions

So, either one of these two language servers doesn't work well, or they're conflicting somehow. I wonder which one "C/C++: Stop Language Server" turns off.

[Kreyren]

FWIW it works on my end even with the extension installed

Maybe this is a somehow related to this thing? (wasn't required to make the reported working i suspect this is caused by emacs extension or theme)

[jankeromnes]

FWIW it works on my end even with the extension installed

@Kreyren To clarify, by "it works on my end", do you mean that in public.c you can hover over the ACR_INFO_COUNT symbol, and the popover shows the correct type (as defined in public.h)?

[Kreyren]

@jankeromnes Nope i am getting following:

I don't see it being defined in the code itself on this snapshot: https://gitpod.io#snapshot/f950a200-b31d-49b2-9ec6-c020a3a57dd2

Defining it (lazy proof of concept because i didn't read the code) seems to result in expected behavior:

[sirspot]

I can clarify a bit. When the ms-vscode.cpptools VS Code extension is NOT installed and the ACR/public.c file is open, it cannot find ACR/public.h and places a red line under it. When I turn off the language server in that case the red line goes away but hovering over ACR_INFO_COUNT has no effect.

Then, when I install the ms-vscode.cpptools VS Code extension and the language server is on, I still get the red line under ACR/public.h but when I turn off the language server it goes away. AND now that the extension is installed I can hover over ACR_INFO_COUNT to see the value is defined as expected (it is defined in an enum in ACR/public.h)

[Kreyren]

The default gitpod environment seems to be able to find it if specified as full path:

@sirspot Can you verify this on your environment? https://gitpod.io/#https://github.com/Kreyren/ACR/blob/699b96b8abe35ba8b7f1db2701dac697d14318a4/src/ACR/public.c

So far looks to me as configuration issue.

[Kreyren]

@sirspot If the behavior is different on your environment then elaborate on what browser were you using at the time (i.e issue related to Microsoft Edge on Windows 10 )

[Kreyren]

also if the changes works on your environment then adding .theia/settings.json with content

{
    "cpp.clangdArgs": "-I/workspace/ACR/include"
}

Seems to resolve the issue.

EDIT: It doesn't

EDIT2: Outputs that clangd is not present, but it should be installed https://github.com/gitpod-io/workspace-images/blob/master/full/Dockerfile#L62

EDIT3: According to apt list --installed clangd is not installed on workspace-full -> Seems as deployment issue

EDIT4: Installing dependencies doesn't seem to affect the issue, seems to be done by design.

[sirspot]

@Kreyren That was a great hint! I found that the clang flags can be stored in a file called compile_flags.txt and I think it works! I am going to test a few things and commit to git but this may be the missing piece of the puzzle :)

EDIT: Confirmed! It now works straight out of the box. The compile_flags.txt file is just briefly mentioned at the bottom of this page https://clang.llvm.org/docs/JSONCompilationDatabase.html for future reference

[Kreyren]

Glad it worked ^-^

@sirspot Can you confirm that without the compiler_flags.txt it works locally?

If it works without that locally then i think that using compile_flags.txt is kinda janky on gitpod -> Should be store this somewhere else?

Few options:

• Extension configuration
• In .gitpod.yml
• In code? (probably a bad idea assuming it could be considered as bloat)

[Kreyren]

Also assuming gitpod not expecting end-users to install ms-vscode cpp extension then we should probably put it in some kind of blacklist with a helpful message specifying why..

[sirspot]

I think the ms-vscode cpp ext is required for debugging c/c++ in gitpod. I don’t remember it working until I got that ext to install.

[Kreyren]

@sirspot It should work out of the box without ms-vscode cpp ext (at least on my end it does and the info above was provided on repository without the extension O.o).