rust-analyzer is an LSP server for the Rust language. It allows editors like vim, emacs, or VS Code to provide IDE-like features for Rust.
This program, rust-analyzer-chromiumos-wrapper, is a wrapper around rust-analyzer. It exists to translate paths between an instance of rust-analyzer running inside the chromiumos chroot and a client running outside the chroot.
It is of course possible to simply run rust-analyzer outside the chroot, but version mismatch issues may lead to a suboptimal experience.
It should run outside the chroot. If invoked in a chromiumos repo in a subdirectory of either chromiumos/src or chromiumos/chroot, it will attempt to invoke rust-analyzer inside the chroot and translate paths. Otherwise, it will attempt to invoke a rust-analyzer outside the chroot and will not translate paths.
It supports none of rust-analyzer‘s command line options, which aren’t necessary for acting as a LSP server anyway.
Outside the chroot, install the rust-analyzer-chromiumos-wrapper binary:
cargo install --path /path-to-a-chromiumos-checkout/src/third_party/toolchain-utils/rust-analyzer-chromiumos-wrapper
Make sure ~/.cargo/bin' is in your PATH, or move/symlink ~/.cargo/bin/rust-analyzer-chromiumos-wrapper` to a location in your PATH.
Configure your editor to use the binary rust-analyzer-chromiumos-wrapper as rust-analyzer. In Neovim, if you're using nvim-lspconfig, this can be done by putting the following in your init.lua:
require('lspconfig')['rust_analyzer'].setup {
cmd = {'rust-analyzer-chromiumos-wrapper'},
}
This configuration is specific to your editor, but see the Rust analyzer manual for more about several different editors.
Once the above general configuration is set up, you'll need to install rust-analyzer inside each chroot where you want to edit code:
sudo emerge rust-analyzer
A wrapper isn't necessary for clangd, because clangd supports the option --path-mappings to translate paths. In principle a similar option could be added to rust-analyzer, obviating the need for this wrapper. See this issue on github.