libc crate fails to build when using fromToolchainFile

[mediocregopher]

Cargo.toml:

[package]
name = "repro"
version = "0.1.0"
edition = "2021"

[dependencies]
libc = "0.2.150"

flake.nix:

{
  inputs = {
    fenix.url = "github:nix-community/fenix";
    naersk.url = "github:nix-community/naersk/master";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11";
  };

  outputs = { self, nixpkgs, naersk, fenix }: {

    packages.x86_64-linux.default = let
      buildSystem = "x86_64-linux";
      pkgs = import nixpkgs { system = buildSystem; };
      fenixPkgs = fenix.packages.${buildSystem};

      naersk-lib = let
        toolchain = fenixPkgs.fromToolchainFile {
          file = ./rust-toolchain.toml;
          sha256 = "sha256-LU4C/i+maIOqBZagUaXpFyWZyOVfQ3Ah5/JTz7v6CG4=";
        };
      in
        pkgs.callPackage naersk {
          cargo = toolchain;
          rustc = toolchain;
        };

    in
      naersk-lib.buildPackage {
        src = ./.;
      };
  };
}

rust-toolchain.toml:

[toolchain]
channel = "nightly-2023-07-23"
components = [ "rustfmt", "rustc-dev", "clippy", "cargo" ]
targets = [
    "x86_64-unknown-linux-musl",
]

This results in an error when building the libc crate:

repro-deps>    Compiling libc v0.2.150
repro-deps> error: failed to run custom build command for `libc v0.2.150`
repro-deps> Caused by:
repro-deps>   process didn't exit successfully: `/build/dummy-src/target/release/build/libc-d79941b6d8ccf44d/build-script-build` (exit status: 101)
repro-deps>   --- stdout
repro-deps>   cargo:rerun-if-changed=build.rs
repro-deps>   --- stderr
repro-deps>   thread 'main' panicked at 'failed to run rustc: /nix/store/0w7x51qky8wf0y4qmvca5l9asd9sl415-rust-nightly-2023-07-23/bin/rustc: error while loading shared libraries: libLLVM-16-rust-1.73.0-nightly.so: cannot open shared object file: No such file or directory
repro-deps>   ', /sources/libc-0.2.150-89d92a4743f9a61002fae18374ed11e7973f530cb3a3255fb354818118b2203c/build.rs:204:9
repro-deps>   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
repro-deps> [naersk] cargo returned with exit code 101, exiting

However if you replace the naersk-lib definition with another using fromToolchainName instead:

      naersk-lib = let
        toolchain = fenixPkgs.fromToolchainName {
          name = "nightly-2023-07-23";
          sha256 = "sha256-LU4C/i+maIOqBZagUaXpFyWZyOVfQ3Ah5/JTz7v6CG4=";
        };
      in
        pkgs.callPackage naersk {
          cargo = toolchain.cargo;
          rustc = toolchain.rustc;
        };

then the project compiles without issue.

I've confirmed that there is indeed a libLLVM-16-rust-1.73.0-nightly.so file in the rust-nightly-2023-07-23 derivation:

 /tmp/repro :: ls -l /nix/store/0w7x51qky8wf0y4qmvca5l9asd9sl415-rust-nightly-2023-07-23/lib/libLLVM-16-rust-1.73.0-nightly.so
lrwxrwxrwx 1 root root 106 Jan  1  1970 /nix/store/0w7x51qky8wf0y4qmvca5l9asd9sl415-rust-nightly-2023-07-23/lib/libLLVM-16-rust-1.73.0-nightly.so -> /nix/store/wih7jgpwmz1sxf00qdzlsg2r1dmvh44m-rustc-nightly-2023-07-23/lib/libLLVM-16-rust-1.73.0-nightly.so

Any help would be much appreciated 🙏

[evanjs]

Encountered this as well and also curious if I'm just doing something wrong.

Working around it for now, but this approach only considers the toolchain version/channel/name:

# rust-toolchain.toml
[toolchain]
channel = "1.82.0"
components = [ "rustfmt", "rustc-dev" ]
targets = [ "x86_64-unknown-linux-gnu" ]
profile = "minimal"

# flake.nix
{
  toolchain =
    let
      toolchainRaw = (builtins.fromTOML (builtins.readFile ./rust-toolchain.toml)).toolchain;
    in
    fenix.packages.${system}.fromToolchainName {
      name = toolchainRaw.channel;
      sha256 = "sha256-yMuSb5eQPO/bHv+Bcf/US8LVMbf/G/0MSfiPwBhiPpk=";
    };

  naersk' = naersk.lib.${system}.override {
    cargo = toolchain.cargo;
    rustc = toolchain.rustc;
  };
}