Rust analyzer does not work in nix flake based development #6105
Description
When I use nix develop and then head into neovim, most tokens have a red squiggly underline and LSP actions, like go to definition, are not completely working.
https://asciinema.org/a/XzG8hoWcLV5NLPSkIgKGSo80i
I googled a bit and found this https://vi.stackexchange.com/questions/45071/rust-analyser-in-neovim-is-underlining-almost-all-words-red-in-working-code. Seems like rust-src is involved.
Using https://zero-to-nix.com/start/init-flake/ on a Rust project, I get
# This flake was initially generated by fh, the CLI for FlakeHub (version 0.1.22)
{
# Flake inputs
inputs = {
flake-schemas.url = "https://flakehub.com/f/DeterminateSystems/flake-schemas/*";
nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*";
rust-overlay = {
url = "https://flakehub.com/f/oxalica/rust-overlay/0.1.*";
inputs.nixpkgs.follows = "nixpkgs";
};
};
# Flake outputs that other flakes can use
outputs = { self, flake-schemas, nixpkgs, rust-overlay }:
let
# Nixpkgs overlays
overlays = [
rust-overlay.overlays.default
(final: prev: {
rustToolchain = final.rust-bin.stable.latest.default.override { extensions = [ "rust-src"]; };
})
];
# Helpers for producing system-specific outputs
supportedSystems = [ "aarch64-darwin" ];
forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
pkgs = import nixpkgs { inherit overlays system; };
});
in {
# Schemas tell Nix about the structure of your flake's outputs
schemas = flake-schemas.schemas;
# Development environments
devShells = forEachSupportedSystem ({ pkgs }: {
default = pkgs.mkShell {
# Pinned packages available in the environment
packages = with pkgs; [
rustToolchain
cargo-edit
cargo-outdated
cargo-watch
rust-analyzer
curl
git
jq
nixpkgs-fmt
];
# Environment variables
env = {
RUST_BACKTRACE = "1";
RUST_SRC_PATH = "${pkgs.rustToolchain}/lib/rustlib/src/rust/library";
};
};
});
};
}And my developmenet environment works well.
So maybe we want to adopt that overlay in the above flake and add it to our flake.nix.
...
overlays = [
rust-overlay.overlays.default
(final: prev: {
rustToolchain = final.rust-bin.stable.latest.default.override { extensions = [ "rust-src"]; };
})
];Line 18 in 838a46d
Here is the salient extract from the LspLog
[ERROR][2025-03-26 10:42:05] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.nix-profile/bin/nixd" "stderr" "I[10:42:05.762] 92884: <-- shutdown(17)\nI[10:42:05.762] 92884: --> reply:shutdown(17)\n"
[START][2025-03-26 10:43:12] LSP logging initiated
[ERROR][2025-03-26 10:43:12] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:43:12.435527-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:43:20] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:43:20.045001-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:43:20] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:43:20.315771-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:43:42] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:43:42.168023-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[START][2025-03-26 10:51:18] LSP logging initiated
[ERROR][2025-03-26 10:51:18] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:51:18.291206-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:51:18] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:51:18.599051-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:51:18] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:51:18.842555-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[ERROR][2025-03-26 10:51:19] ...p/_transport.lua:36 "rpc" "/Users/michaelfortunato/.local/share/nvim/mason/bin/rust-analyzer" "stderr" "2025-03-26T10:51:19.400147-05:00 ERROR can't load standard library, try installing `rust-src` sysroot_path=/nix/store/w351i7f68y33knpn5134zjnnnzr815ki-rust-with-components-2025-02-20\n"
[START][2025-03-26 12:59:13] LSP logging initiated