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Editor Setup: Neovim

This document assumes that you have a functioning install of Neovim, are familiar with its configuration system, and can install plugins using the plugin manager of your choice. For brevity, instructions here are written to target the lazy.nvim plugin manager.

Table of Contents

Install clangd

clangd is a language server for C and C++ projects. For installation details for specific platforms, refer to the official documentation. Only the steps for installing clangd itself will be assumed; further sections of this guide will walk a user through integrating clangd with their editor.

Generate the Compilation Database

If you have not already, generate the compilation database by invoking the following from the root of the project:

python tools/devtools/gen_compile_commands.py

You should now see a file named compile_commands.json in the root of the project. This file will be used to instruct the clangd language server on how to compile individual source files.

Automatically Launch clangd

If you have not already, install and configure nvim-lspconfig by adding the following configuration to the setup function in your init.lua:

require("lazy").setup({
  -- <previous configuration above this line>
  {
    "neovim/nvim-lspconfig",
    opts = {
      servers = {
        clangd = {
          root_dir = function(fname)
            return require("lspconfig.util").root_pattern(
              "Makefile",
              "build.ninja",
              "CMakeLists.txt",
              "compile_commands.json",
              "compile_flags.txt",
              "configure.ac",
              "configure.in",
              "config.h.in",
              "meson.build",
              "meson.options",
            )(fname) or require("lspconfig.util").find_git_ancestor(fname)
          end,
          cmd = {
            "clangd",
            "--background-index",
            "--clang-tidy",
            "--header-insertion=iwyu",
            "--completion-style=detailed",
            "--function-arg-placeholders",
            "--fallback-style=llvm",
          },
          init_options = {
            usePlaceholders = true,
            completeUnimported = true,
            clangdFileStatus = true,
          },
        },
      },
    },
  },
})

This configuration will launch the clangd language server when opening source files belonging to a C or C++ project, identified by the presence of any of a set of common files in an associated git repository. Further configuration of the language server is left to user-preference.

Optional: Integrate Treesitter

If you have not already, install and configure nvim-treesitter by adding the following configuration to the setup function in your init.lua:

require("lazy").setup({
  -- <previous configuration above this line>
  {
    "nvim-treesitter/nvim-treesitter",
    build = ":TSUpdate",
    config = function()
      local configs = require("nvim-treesitter.configs")
      configs.setup({
        ensure_installed = {
          "c",
          "cpp",
        },
        sync_install = false,
        highlight = { enable = true },
        indent = { enable = true },
      })
    end
  }
})

Then, restart Neovim to load the new configuration. lazy should automatically begin installing nvim-treesitter.

Optional: Install Extensions to clangd

If desired, install and configure clangd_extensions.nvim by following the instructions in its README.md. These extensions are not supported by the generic Language Server Protocol specification, and hence must be included via a separate plugin.

Optional: Add Language Support for Meson

[!NOTE] This section currently refers to an extension which, while functional, is unmaintained. It may be replaced by instructions for a different extension in the future.

If desired, install mesonlsp by following the instructions in the Installation section of its README.md. To configure the extension for use with nvim-lspconfig, add the following configuration snippet to the setup function in your init.lua:

require("lazy").setup({
  -- <previous configuration above this line>
  {
    "neovim/nvim-lspconfig",
    opts = {
      servers = {
        -- <previous configuration above this line>
        mesonlsp = {
          root_dir = function(fname)
            return require("lspconfig.util").root_pattern(
              "meson.build",
              "meson.options",
              "meson_options.txt",
            )(fname) or require("lspconfig.util").find_git_ancestor(fname)
          end,
          cmd = { 'mesonlsp', '--lsp', },
          filetypes = { 'meson' },
        },
      },
    },
  },
})