Update clang from lspconfig, fix keybinds for header/source switching

and symbol info. Also start clang with more and different options for
better handling in larger projects:

+            "--background-index",         -- Enables background indexing
+            "--clang-tidy",               -- Enables clang-tidy diagnostics
+            "--completion-style=bundled", -- Simpler completions for faster performance
+            "--rename-file-limit=0",      -- No limit on renaming files
+            "--header-insertion=iwyu",    -- Suggest missing includes based on IWYU
+            "--inlay-hints",              -- Enable inlay hints for parameter and type information
+            "--limit-results=70",         -- Limit autocompletion and symbol results
+            "--suggest-missing-includes", -- Still show missing includes suggestions
+            "--pch-storage=disk",         -- Stores precompiled headers on disk (fixes the issue where system ran out of memory when indexing large projects, not a huge performance hit on fast m2 ssds)
+            "--log=error",                -- Log only errors

home/.config/nvim/lua/language_servers/clangd.lua

@@ -1,54 +1,123 @@
-local function switch_between_header_and_source(bufnr)
+local util = require "lspconfig.util"
-    local util = require("lspconfig/util")
+
+-- https://clangd.llvm.org/extensions.html#switch-between-sourceheader
+local function switch_source_header(bufnr)
     bufnr = util.validate_bufnr(bufnr)
     local clangd_client = util.get_active_client_by_name(bufnr, "clangd")
     local params = { uri = vim.uri_from_bufnr(bufnr) }
-    -- invert this with an early return
+    if clangd_client then
-    if not clangd_client then
-        print "method textDocument/switchSourceHeader is not supported by any servers active on the current buffer"
-        return
-    end
-
         clangd_client.request("textDocument/switchSourceHeader", params, function(err, result)
             if err then
                 error(tostring(err))
             end
             if not result then
-            print("Corresponding file cannot be determined")
+                print "Corresponding file cannot be determined"
                 return
             end
-        vim.api.nvim_command("drop " .. vim.uri_to_fname(result))
+            vim.api.nvim_command("edit " .. vim.uri_to_fname(result))
+        end, bufnr)
+    else
+        print "method textDocument/switchSourceHeader is not supported by any servers active on the current buffer"
+    end
+end
+
+local function symbol_info()
+    local bufnr = vim.api.nvim_get_current_buf()
+    local clangd_client = util.get_active_client_by_name(bufnr, "clangd")
+    if not clangd_client or not clangd_client.supports_method "textDocument/symbolInfo" then
+        return vim.notify("Clangd client not found", vim.log.levels.ERROR)
+    end
+    local params = vim.lsp.util.make_position_params()
+    clangd_client.request("textDocument/symbolInfo", params, function(err, res)
+        if err or #res == 0 then
+            -- Clangd always returns an error, there is not reason to parse it
+            return
+        end
+        local container = string.format("container: %s", res[1].containerName) ---@type string
+        local name = string.format("name: %s", res[1].name) ---@type string
+        vim.lsp.util.open_floating_preview({ name, container }, "", {
+            height = 2,
+            width = math.max(string.len(name), string.len(container)),
+            focusable = false,
+            focus = false,
+            border = require("lspconfig.ui.windows").default_options.border or "single",
+            title = "Symbol Info",
+        })
     end, bufnr)
 end
 
-local M = {
+local lsp_maps = {
+    {
+        "<leader>ko",
+        function() switch_source_header(0) end,
+    },
+    {
+        "K",
+        symbol_info,
+    }
+}
+local keymaps = { n = {} }
+for i, _ in ipairs(lsp_maps) do
+    local binding, cmd = unpack(lsp_maps[i])
+    keymaps.n[binding] = { cmd = cmd }
+end
+require("utils").add_keymaps(keymaps)
+
+local root_files = {
+    ".clangd",
+    ".clang-tidy",
+    ".clang-format",
+    "compile_commands.json",
+    "compile_flags.txt",
+    "configure.ac", -- AutoTools
+}
+
+local default_capabilities = {
+    textDocument = {
+        completion = {
+            editsNearCursor = true,
+        },
+    },
+    offsetEncoding = { "utf-8", "utf-16" },
+}
+
+return {
+    default_config = {
         cmd = {
             "clangd",
-        "--background-index",
+            "--background-index",         -- Enables background indexing
-        "--clang-tidy",
+            "--clang-tidy",               -- Enables clang-tidy diagnostics
-        "--completion-style=bundled",
+            "--completion-style=bundled", -- Simpler completions for faster performance
-        -- "--cross-file-rename", // This has been deprecated
+            "--rename-file-limit=0",      -- No limit on renaming files
-        "--rename-file-limit=0",
+            "--header-insertion=iwyu",    -- Suggest missing includes based on IWYU
-        "--header-insertion=iwyu",
+            "--inlay-hints",              -- Enable inlay hints for parameter and type information
-        "--inlay-hints",
+            "--limit-results=70",         -- Limit autocompletion and symbol results
-        -- "--compile-commands-dir=build/",
+            "--suggest-missing-includes", -- Still show missing includes suggestions
+            "--pch-storage=disk",         -- Stores precompiled headers on disk (fixes the issue where system ran out of memory when indexing large projects, not a huge performance hit on fast m2 ssds)
+            "--log=error",                -- Log only errors
         },
-    commands = {
+        filetypes = { "c", "cpp", "objc", "objcpp", "cuda", "proto" },
-        ClangdSwitchSourceHeader = {
+        root_dir = function(fname)
-            function()
+            return util.root_pattern(unpack(root_files))(fname) or util.find_git_ancestor(fname)
-                switch_between_header_and_source(0)
         end,
-            description = "Switch between source/header",
+        single_file_support = true,
+        capabilities = default_capabilities,
+    },
+    docs = {
+        description = [[
+https://clangd.llvm.org/installation.html
+
+- **NOTE:** Clang >= 11 is recommended! See [#23](https://github.com/neovim/nvim-lsp/issues/23).
+- If `compile_commands.json` lives in a build directory, you should
+  symlink it to the root of your source tree.
+    ln -s /path/to/myproject/build/compile_commands.json /path/to/myproject/
+- clangd relies on a [JSON compilation database](https://clang.llvm.org/docs/JSONCompilationDatabase.html)
+specified as compile_commands.json, see https://clangd.llvm.org/installation#compile_commandsjson
+]],
+        default_config = {
+            root_dir =
+            [[      root_pattern(        ".clangd",        ".clang-tidy",        ".clang-format",        "compile_commands.json",        "compile_flags.txt",        "configure.ac",        ".git"      )    ]],
+            capabilities = [[default capabilities, with offsetEncoding utf-8]],
         },
     },
 }
-
-function M.post_setup()
-    require("utils").add_keymaps({
-        n = {
-            ["<leader>ko"] = { cmd = ":ClangdSwitchSourceHeader<CR>" }
-        },
-    })
-end
-
-return M