From bf4ca036acd7e027724de3f70b6d1f0ae7e1ba50 Mon Sep 17 00:00:00 2001
From: Peter Cai <peter@typeblog.net>
Date: Sun, 7 Aug 2022 22:59:34 -0400
Subject: [PATCH] neovim: Configure LSP for Rust

---
 nvim/.config/nvim/init.vim        |  1 +
 nvim/.config/nvim/lua/mylsp.lua   | 81 +++++++++++++++++++++++++++++++
 nvim/.config/nvim/lua/plugins.lua | 10 +++-
 3 files changed, 90 insertions(+), 2 deletions(-)
 create mode 100644 nvim/.config/nvim/lua/mylsp.lua

diff --git a/nvim/.config/nvim/init.vim b/nvim/.config/nvim/init.vim
index b062cd5..91aef1d 100644
--- a/nvim/.config/nvim/init.vim
+++ b/nvim/.config/nvim/init.vim
@@ -1,5 +1,6 @@
 " Packer plugins
 lua require('plugins')
+lua require('mylsp')
 
 " Gruvbox Theme (colorscheme applied from plugins.lua)
 if has('termguicolors')
diff --git a/nvim/.config/nvim/lua/mylsp.lua b/nvim/.config/nvim/lua/mylsp.lua
new file mode 100644
index 0000000..d60bef6
--- /dev/null
+++ b/nvim/.config/nvim/lua/mylsp.lua
@@ -0,0 +1,81 @@
+-- Custom LSP configuration
+-- This cannot be done in the config function from Packer
+-- because it somehow does not work well with make_client_capabilities()
+require("mason-lspconfig").setup({
+    ensure_installed = { "rust_analyzer" }
+})
+
+local opts = { noremap=true, silent=true }
+vim.keymap.set('n', '<space>e', vim.diagnostic.open_float, opts)
+vim.keymap.set('n', '[d', vim.diagnostic.goto_prev, opts)
+vim.keymap.set('n', ']d', vim.diagnostic.goto_next, opts)
+vim.keymap.set('n', '<space>q', vim.diagnostic.setloclist, opts)
+
+local cmp = require 'cmp'
+cmp.setup({
+    mapping = {
+        ['<C-d>'] = cmp.mapping.scroll_docs(-4),
+        ['<C-f>'] = cmp.mapping.scroll_docs(4),
+        ['<C-Space>'] = cmp.mapping.complete(),
+        ['<CR>'] = cmp.mapping.confirm {
+            behavior = cmp.ConfirmBehavior.Replace,
+            select = true,
+        },
+        ['<Tab>'] = cmp.mapping(function(fallback)
+            if cmp.visible() then
+                cmp.select_next_item()
+            else
+                fallback()
+            end
+        end, { 'i', 's' }),
+        ['<S-Tab>'] = cmp.mapping(function(fallback)
+            if cmp.visible() then
+                cmp.select_prev_item()
+            else
+                fallback()
+            end
+        end, { 'i', 's' }),
+    },
+    sources = {
+        { name = 'nvim_lsp' },
+    },
+})
+
+-- Rewrite LSP capabilities (to enable completion)
+local capabilities = require('cmp_nvim_lsp').update_capabilities(vim.lsp.protocol.make_client_capabilities())
+
+-- Use an on_attach function to only map the following keys
+-- after the language server attaches to the current buffer
+local on_attach = function(client, bufnr)
+    -- Mappings.
+    -- See `:help vim.lsp.*` for documentation on any of the below functions
+    local bufopts = { noremap=true, silent=true, buffer=bufnr }
+    vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, bufopts)
+    vim.keymap.set('n', 'gd', vim.lsp.buf.definition, bufopts)
+    vim.keymap.set('n', 'K', vim.lsp.buf.hover, bufopts)
+    vim.keymap.set('n', 'gi', vim.lsp.buf.implementation, bufopts)
+    vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, bufopts)
+    vim.keymap.set('n', '<space>wa', vim.lsp.buf.add_workspace_folder, bufopts)
+    vim.keymap.set('n', '<space>wr', vim.lsp.buf.remove_workspace_folder, bufopts)
+    vim.keymap.set('n', '<space>wl', function()
+        print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
+    end, bufopts)
+    vim.keymap.set('n', '<space>D', vim.lsp.buf.type_definition, bufopts)
+    vim.keymap.set('n', '<space>rn', vim.lsp.buf.rename, bufopts)
+    vim.keymap.set('n', '<space>ca', vim.lsp.buf.code_action, bufopts)
+    vim.keymap.set('n', 'gr', vim.lsp.buf.references, bufopts)
+    vim.keymap.set('n', '<space>f', vim.lsp.buf.formatting, bufopts)
+end
+
+require('lspconfig')['rust_analyzer'].setup({
+    on_attach = on_attach,
+    settings = {
+        ['rust_analyzer'] = {
+            cargo = {
+                autoreload = true,
+                buildScripts = { enable = true },
+            },
+        },
+    },
+    capabilities = capabilities,
+})
diff --git a/nvim/.config/nvim/lua/plugins.lua b/nvim/.config/nvim/lua/plugins.lua
index 9ec87a5..4d0ec50 100644
--- a/nvim/.config/nvim/lua/plugins.lua
+++ b/nvim/.config/nvim/lua/plugins.lua
@@ -4,8 +4,14 @@ return require('packer').startup(function(use)
     -- Packer can manage itself
     use 'wbthomason/packer.nvim'
 
-    -- External dependencies management
-    use "williamboman/mason.nvim"
+    -- LSP stuff
+    use {
+        "williamboman/mason.nvim",
+        "williamboman/mason-lspconfig.nvim",
+        "neovim/nvim-lspconfig",
+        "hrsh7th/nvim-cmp",
+        "hrsh7th/cmp-nvim-lsp",
+    }
 
     -- Gruvbox theme
     use {