feat(nvim): add Rust LSP support

configs/nixos/modules/shell/nvim/config.lua

@@ -6,6 +6,31 @@ require("nord").setup({
 })
 vim.cmd.colorscheme("nord")
 
+-- Keep floating windows distinct from the current line highlight.
+vim.api.nvim_set_hl(0, "NormalFloat", { bg = "#2e3440" })
+vim.api.nvim_set_hl(0, "FloatBorder", { fg = "#88c0d0", bg = "#2e3440" })
+
+local open_floating_preview = vim.lsp.util.open_floating_preview
+vim.lsp.util.open_floating_preview = function(contents, syntax, opts, ...)
+  opts = opts or {}
+  opts.border = opts.border or "rounded"
+  return open_floating_preview(contents, syntax, opts, ...)
+end
+
+-- Format Rust buffers before writing them.
+vim.api.nvim_create_autocmd("BufWritePre", {
+  pattern = "*.rs",
+  callback = function(args)
+    vim.lsp.buf.format({
+      bufnr = args.buf,
+      timeout_ms = 2000,
+      filter = function(client)
+        return client.name == "rust_analyzer"
+      end,
+    })
+  end,
+})
+
 -- Conceal markdown syntax in markdown buffers.
 -- conceallevel is window-local, so it is set with opt_local when the filetype
 -- is applied to the buffer's window.