serenity/Documentation/EmacsConfiguration.md

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. You can use the following .clangd file placed in the project root:

CompileFlags:
  CompilationDatabase: Build/i686
  Add:
    - "-D__serenity__"
    - "-UNO_TLS"
    - "-I/path/to/serenity/Toolchain/Local/i686/i686-pc-serenity/include/c++/11.2.0"
    - "-I/path/to/serenity/Toolchain/Local/i686/i686-pc-serenity/include/c++/11.2.0/i686-pc-serenity"

You will need to change /path/to/serenity and change 11.2.0 to whatever your GCC toolchain version at the time is.

Run cmake (Meta/serenity.sh run or similar) at least once for this to work, as it will generate the Build/i686/compile_commands.json that is needed by clangd.

lsp-mode

(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 This is the easiest solution, but your system clangd might be out of date.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 Serenity'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:

• format-all-mode
• clang-format-plus