Add Rust support with rustaceanvim

.github/copilot-instructions.md

@@ -1,12 +1,12 @@
 # Copilot instructions
 
-Personal Neovim config (Lua, lazy.nvim) for Neovim 0.12+, used on Windows with pwsh for C#/.NET, Go and Vite/React work. CI checks are described in `README.md`.
+Personal Neovim config (Lua, lazy.nvim) for Neovim 0.12+, used on Windows with pwsh for C#/.NET, Go, Rust and Vite/React work. CI checks are described in `README.md`.
 
 ## Layout
 
 - `init.lua` loads `lua/simonkdev/`: `options.lua`, `keymaps.lua`, `autocmds.lua`, then `lazy_init.lua`, which bootstraps lazy.nvim.
 - Plugin specs live in `lua/simonkdev/lazy/`, with `lsp/` and `debugger/` subfolders. Each file returns a lazy.nvim spec.
-- Language servers are installed and enabled by mason-lspconfig (`lazy/lsp/mason.lua`) and configured with `vim.lsp.config` (`lazy/lsp/lspconfig.lua`).
+- Language servers are installed and enabled by mason-lspconfig (`lazy/lsp/mason.lua`) and configured with `vim.lsp.config` (`lazy/lsp/lspconfig.lua`). The exception is Rust: rustaceanvim (`lazy/rust.lua`) runs the toolchain's rust-analyzer, so never add `rust_analyzer` to mason-lspconfig.
 - Per-filetype settings go in `after/ftplugin/<filetype>.lua`.
 - `lazy-lock.json` pins every plugin's commit. `tests/smoke.lua` is the headless startup test.
 - Treesitter uses nvim-treesitter's `main` branch: it only installs parsers (`lazy/treesitter.lua`), and Neovim's built-in treesitter does highlighting, started per buffer from a FileType autocmd. There is no `nvim-treesitter.configs`.

README.md

@@ -7,6 +7,7 @@ Other than small retouch the setup is virtually identitcal to Josean's setup, ch
 
 - Neovim 0.12 or later.
 - A C compiler on `PATH` (e.g. gcc from MinGW) to build treesitter parsers and telescope-fzf-native. nvim-treesitter also needs the `tree-sitter` CLI, which Mason installs; on a fresh machine parsers install once Mason has it.
+- For Rust, rust-analyzer from your toolchain: `rustup component add rust-analyzer`. rustaceanvim starts it (and Mason's codelldb for debugging); don't install rust-analyzer through Mason.
 
 ## Updates
 
@@ -18,7 +19,7 @@ Other than small retouch the setup is virtually identitcal to Josean's setup, ch
 Every pull request (and push to `main`) runs `.github/workflows/ci.yml`:
 
 - **StyLua**: `stylua --check .` using `.stylua.toml`. Fix locally with `stylua .`.
-- **Startup smoke test (Windows)**: installs every plugin from `lazy-lock.json` and every treesitter parser into empty directories, opens a Lua and a C# buffer, loads all plugins, and fails on any error. It also checks wiring that wouldn't raise an error: every mason-lspconfig server name resolves to an LSP config, Go/TSX/Lua buffers get the expected formatter and treesitter highlighting, files without a formatter get trailing whitespace trimmed (patches excepted), and web filetypes use 2-space indents. Mason package download failures are ignored because they depend on the network, not the config; language servers aren't installed in headless runs, so they're never started.
+- **Startup smoke test (Windows)**: installs every plugin from `lazy-lock.json` and every treesitter parser into empty directories, opens a Lua and a C# buffer, loads all plugins, and fails on any error. It also checks wiring that wouldn't raise an error: every mason-lspconfig server name resolves to an LSP config, Go/TSX/Lua/Rust buffers get the expected formatter and treesitter highlighting, files without a formatter get trailing whitespace trimmed (patches excepted), and web filetypes use 2-space indents. Mason package download failures are ignored because they depend on the network, not the config; language servers aren't installed in headless runs, so they're never started.
 
 Run the smoke test locally from this directory:
 

after/ftplugin/rust.lua

@@ -0,0 +1,12 @@
+-- :make (<leader>b) runs `cargo build` and loads rustc's errors into the quickfix list
+vim.cmd.compiler("cargo")
+vim.opt_local.makeprg = "cargo build"
+
+local function map(lhs, subcommand, desc)
+	vim.keymap.set("n", lhs, function()
+		vim.cmd.RustLsp(subcommand)
+	end, { buffer = true, desc = desc })
+end
+map("<leader>rr", "runnables", "Rust: Runnables")
+map("<leader>rd", "debuggables", "Rust: Debuggables")
+map("<leader>re", "explainError", "Rust: Explain Error")

lazy-lock.json

@@ -46,6 +46,7 @@
   "nvim-ts-context-commentstring": { "branch": "main", "commit": "6141a40173c6efa98242dc951ed4b6f892c97027" },
   "nvim-web-devicons": { "branch": "master", "commit": "ec309a0eaff6ea967e58c275996155ab5c16938d" },
   "plenary.nvim": { "branch": "master", "commit": "74b06c6c75e4eeb3108ec01852001636d85a932b" },
+  "rustaceanvim": { "branch": "main", "commit": "9cb125de42c0256ed1bc1f9ded8d8f0381317a17" },
   "substitute.nvim": { "branch": "main", "commit": "0d2077398552f069abccbd964a26dd7cd26882cd" },
   "telescope-fzf-native.nvim": { "branch": "main", "commit": "b25b749b9db64d375d782094e2b9dce53ad53a40" },
   "telescope.nvim": { "branch": "master", "commit": "40aedd8a68c78a656a10a8d62d80c54af59420fb" },

lua/simonkdev/lazy/debugger/dap-virtual-text.lua

@@ -3,6 +3,6 @@ return {
 	dependencies = {
 		"mfussenegger/nvim-dap",
 	},
-	ft = { "go", "cs" },
+	ft = { "go", "cs", "rust" },
 	opts = {},
 }

lua/simonkdev/lazy/debugger/mason-nvim-dap.lua

@@ -7,8 +7,12 @@ return {
 			"chrome-debug-adapter",
 			"js-debug-adapter",
 			"coreclr",
+			"codelldb", -- Rust, through rustaceanvim
+		},
+		handlers = {
+			-- rustaceanvim registers codelldb and Rust's debug configurations itself (lazy/rust.lua)
+			codelldb = function() end,
 		},
-		handlers = {},
 	},
 	event = "VeryLazy",
 }

lua/simonkdev/lazy/rust.lua

@@ -0,0 +1,8 @@
+-- Rust: rustaceanvim starts and configures rust-analyzer itself, so don't also enable it through mason-lspconfig.
+-- It runs the rust-analyzer on PATH (`rustup component add rust-analyzer`), which matches the toolchain, and
+-- debugs with Mason's codelldb, which it finds on its own. Clippy is the on-save checker when it's installed.
+return {
+	"mrcjkb/rustaceanvim",
+	version = "^9",
+	lazy = false, -- a filetype plugin that already loads lazily
+}

lua/simonkdev/lazy/testing.lua

@@ -17,6 +17,7 @@ return {
 						dap_settings = { type = "coreclr" },
 					}),
 					require("neotest-golang")(), -- debugs tests through nvim-dap-go
+					require("rustaceanvim.neotest"), -- debugs tests through codelldb
 				},
 				status = { virtual_text = true },
 				output = {

lua/simonkdev/lazy/treesitter.lua

@@ -21,6 +21,8 @@ return {
 				"gomod",
 				"gosum",
 				"gowork",
+				"rust",
+				"toml",
 				"css",
 				"html",
 				"json",

tests/smoke.lua

@@ -166,14 +166,22 @@ local function run()
 		for _, name in ipairs({ "gopls", "ts_ls", "lua_ls", "csharp_ls" }) do
 			check(vim.tbl_contains(servers, name), name .. " is missing from mason-lspconfig ensure_installed")
 		end
+		-- rustaceanvim runs rust-analyzer; a second client from lspconfig would duplicate every result.
+		check(not vim.lsp.is_enabled("rust_analyzer"), "rust_analyzer is enabled alongside rustaceanvim")
 		for _, name in ipairs(servers) do
 			local config = vim.lsp.config[name]
 			check(config and config.cmd ~= nil, "no LSP config named " .. name)
 		end
 
 		-- Scratch buffers get FileType without BufEnter, so nvim-lint doesn't try to run eslint_d.
 		local conform = require("conform")
-		local expected = { go = "goimports", typescriptreact = "prettier", lua = "stylua", text = "trim_whitespace" }
+		local expected = {
+			go = "goimports",
+			typescriptreact = "prettier",
+			lua = "stylua",
+			rust = "trim_whitespace", -- after rust-analyzer's rustfmt
+			text = "trim_whitespace",
+		}
 		for ft, formatter in pairs(expected) do
 			local buf = vim.api.nvim_create_buf(true, true)
 			vim.bo[buf].filetype = ft