Emacs Project Configuration

Emacs can be configured with lsp-mode and clangd to work well.

clangd

The official clangd extension can be used for C++ comprehension.

Run cmake (Meta/ladybird.py run ladybird or similar) at least once for clangd to work, as doing so will generate the Build/release/compile_commands.json that is needed by clangd.

lsp-mode

lisp

(use-package lsp-mode
  :hook ((c++-mode) . lsp-deferred)
  :commands lsp
  :config
  (setq lsp-clients-clangd-args '("-j=4" "-background-index" "--log=error" "--clang-tidy" "--enable-config"))
  ;; Optionally, set the location of clangd -- See notes below for options.
  (setq lsp-clangd-binary-path "/usr/bin/clangd"))

clangd

There are a few different ways to specify which clangd to use:

By default, without configuration lsp-mode will try to find and use your system clangd. This is the easiest solution, but your system clangd might be out of date.
You can manually specify any clangd binary with lsp-clangd-binary-path, as shown in the use-package example above.
You can have lsp-mode manage your clangd installation with emacs' lsp-install-server. This will install a clangd binary for you.
You can build the LLVM toolchain, including clangd, from Ladybird's repository. This is an advanced option that is not currently documented.

clang-format

There are multiple packages to handle auto formatting with clang-format, within emacs. Choose what works best for your setup:

Alternatively, this can be done without additional packages, using lsp-mode. You can use the following .dir-locals.el file placed in the project root:

lisp

((c++-mode
  (eval add-hook 'before-save-hook #'lsp-format-buffer nil t)))