Clangd

Introduction

clangd is a clang-based language server. It brings IDE features (e.g. diagnostics, code completion, code navigations) to your editor.

Getting clangd

See instructions.

Googlers: clangd has been installed on your glinux by default, just use /usr/bin/clangd.

Alternative: use the following command to build clangd from LLVM source, and you will get the binary at out/Release/tools/clang/third_party/llvm/build/bin/clangd.

tools/clang/scripts/build_clang_tools_extra.py --fetch out/Release clangd

Setting Up

Make sure generated ninja files are up-to-date.

gn gen out/Release

Generate the compilation database, clangd needs it to know how to build a source file.

tools/clang/scripts/generate_compdb.py -p out/Release > compile_commands.json

Note: the compilation database is not re-generated automatically, you'd need to regenerate it manually when you have new files checked in.

Optional: build chrome normally. This ensures generated headers exist and are up-to-date. clangd will still work without this step, but it may give errors or inaccurate results for files which depend on generated headers.

ninja -C out/Release chrome

Use clangd in your favourite editor, see detailed instructions.

Index

By default, clangd only knows the files you are currently editing. To provide project-wide code navigations (e.g. find references), clangd neesds a project-wide index.

You can pass an experimental --background-index command line argument to clangd, clangd will incrementally build an index of Chromium in the background. Note: the first index time may take hours (for reference, it took 2~3 hours on a 48-core, 64GB machine).

A full index of Chromium (including v8, blink) takes ~550 MB disk space and ~2.7 GB memory in clangd.

Questions

If you have any questions, reach out to clangd-dev@lists.llvm.org.