Language servers

I’ll update this when I do a fresh install of Fedora and set things up. This is for a rather old version of Ubuntu (18.04.6).

You might want to use a language server if you want IDE-like capabilities built into vim. Here’s how I set up my language servers for C++ and Python.

Prerequisites: Neovim (not required!) and language server packages.

You don’t need Neovim (nvim) to use a language server, but I used Neovim, so that’s what’s here. Here’s how I set up Neovim.

C++ language servers.

You’ll also want llvm and clangd-10. llvm was already set up on Ubuntu-18.04.6. I’ll update this once I do a fresh install with Fedora, but I was able to install this using apt-get.

sudo apt-get install clangd-10

Not the most recent version of clangd, but it’ll have to do.

This is the language server for C++.

Python language servers.

For python, Niels uses python-lsp-server and pyright-langserver. I couldn’t get this working on my setup, because everything was too old. I’ll update this when I upgrade my Linux distro.

Plug for Neovim.

Plug is a super simple package manager for VIM and Neovim. The instruction from their README that I used is

sh -c 'curl -fLo "${XDG_DATA_HOME:-$HOME/.local/share}"/nvim/site/autoload/plug.vim --create-dirs \
       https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim'

This should download a file in ${HOME}/.local/share/nvim/site/autoload/plug.vim.

Adding language server functionality to Neovim.

Now that plug is installed, you should issue the command in nvim:

:PlugInstall nvim-lspconfig

and then put:

call plug#begin()
Plug 'neovim/nvim-lspconfig'
call plug#end()

in your .vimrc.

The language server settings are found in the init.vim of my dotfiles, which are pretty much a copy-paste of the same file from Niels’ dotfiles.

I’ll annotate that at some point!

Giving the language server what it wants: C++.

You need to make a special file, compile_commands.json, which is just a record of the commands used to compile your C++ library.

One way to do this uses CMake. When you do your normal cmake command, use the following flag:

cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON

Then, compile_commands.json will appear in your build directory. Unfortunately, this will not contain what is needed to hop to a header file. For that, you need to append the header information to it. A script is available for that:

pip install --user compdb

Then,

compdb -p build/ list > compile_commands.json

where build/ is supposed to be the path to your CMake build directory, will append the header information and make a new compile_commands.json with that in it.

Now issue a command like:

nvim **/*.cpp **/*.cu **/*.hpp **/*.hxx **/*.h

to open all the files in your project. You can use :b <file> to jump around to different files that way. Try using ctrl-[ on a function or object, even ones defined in the standard lib. You’ll see that you’ve jumped to it’s definition!

I’ll add more tricks with it as I use it (and finish annotating the init.vim file for Neovim!).

Giving the language server what it wants: Python.

Will update when Python language servers are working on my setup! I think?? you just open the Python files that are involved in your project, and it should allow you to follow references just like that! Python is magical like that.