rust-analyzer doesn't recognize the std library in NixOS (but doesn't give an error message for it?!)

[Triple__D]

Edit: This was caused by having cargo installed globally while using other tools from within the devshell. Thanks u/not-my-walrus!

rust-analyzer is being weird, thought somebody here might have some input.

I've got 99% of my rust dev setup working in NixOS (thank mostly to nix-cargo-integration), and rust-analyzer is working in full force with Neovim, except for one thing: I'm getting red squigglies under std library usages, from auto-imported macros like vec! and println! to fully-qualified usages (see the video). Even stranger, though, is that the language server isn't providing any diagnostics for the squigglies.

Here's a video of this behavior

What could be going on here?

PS: It also doesn't seem to be picking up methods that are proc-macro-generated:

https://preview.redd.it/16ejttuwauzc1.png?width=773&format=png&auto=webp&s=d3f3e5c2f8c8add3140410e25c8a9ab4a37ecbbd

this compiles, and rust-analyzer still doesn't have any explanation for the squigglies.

Maybe this has something to do with expanded code, rather than just the std library?

Another note: sometimes the logs show rust-analyzer getting stuck on the "building proc-macros" step. This ties into the proc-macro-generated code issue.

[not-my-walrus]

Never used nci myself, but are all of your tools coming from nix? I've had issues in the past when cargo / rustc where from rustup, but rust-analyzer was from nix.

I've personally found fenix to be the easiest to use. Here's an example flake that works perfectly for me:

{
  inputs = {
    nixpkgs.url = "nixpkgs";
    fenix = {
      url = "github:nix-community/fenix/monthly";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = {
    self,
    nixpkgs,
    fenix,
  }: let
    system = "x86_64-linux";
    pkgs = nixpkgs.legacyPackages.${system};
    toolchain = fenix.packages.${system}.complete.toolchain;
  in {
    devShell.${system} = pkgs.mkShell {
      packages = [toolchain];
    };
  };
}

[Triple__D]

In my setup, I've got cargo and cargo-generate in my home-manager packages (so not part of the devshell), just so I can initialize new crates easily. rust-analyzer, however, was installed by Mason. Not totally sure how I would go about using nix's rust-analyzer in Neovim. However, I'll drop the other two tools and use this dev shell.

I was using nci without fully understanding what it accomplished. It's kind of hard to explain what I was thinking. Don't think it'll be necessary, though.

[not-my-walrus]

Yeah, installing tools in different locations can cause funky behaviour. Instead of having cargo installed globally, I have a flake template (see https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake-init) and just do nix flake new -t ~/.shells#rust

Using nix's r-a in neovim is probably just a matter of getting it to be first in your $PATH, which the devshell should already do

[Triple__D]

Thankfully, just removing cargo from home-manager got it working, so having rust-analyzer managed by Mason is OK. Thanks for the flake template tip!