`unresolved extern crate` on Nixos

rust-analyzer version: rust-analyzer 1.80.0-nightly (d84b903 2024-05-19)

rustc version: rustc 1.80.0-nightly (d84b90375 2024-05-19)

editor or extension: NeoVim configured with lspconfig

relevant settings:

rust_analyzer = {
  cargo = {
    features = "all",
  },
  rustc = { source = "discover" },
},

repository link (if public, optional): rustc_plugin example

steps to reproduce:
Clone the example from https://github.com/cognitive-engineering-lab/rustc_plugin/ and change the crate:

git clone https://github.com/cognitive-engineering-lab/rustc_plugin/
cd example/print-all-items
sed -i 's;rustc_plugin = { path = "../.." };rustc_plugin = "=0.10.0-nightly-2024-05-20"' Cargo.toml

Create a shell.nix with the following content:

{ nixpkgs ? import <nixpkgs> { }}:

let
  rustOverlay = builtins.fetchTarball "https://github.com/oxalica/rust-overlay/archive/master.tar.gz";
  pinnedPkgs = nixpkgs.fetchFromGitHub {
    owner  = "NixOS";
    repo   = "nixpkgs";
    rev    = "b3fcfcfabd01b947a1e4f36622bbffa3985bdac6";
    sha256 = "0va68ddkrqb6j349rsbkjhdq7m243kg9njcqhnx9p2sbrcl2g5l8";
  };
  pkgs = import pinnedPkgs {
    overlays = [ (import rustOverlay) ];
  };
  rust_pkg = pkgs.rust-bin.nightly."2024-05-20".default.override {
    extensions = ["rust-src" "rustc" "rustc-dev" "llvm-tools" "rust-analyzer" "cargo"];
  };
in
  pkgs.mkShell {
    buildInputs = with pkgs; [
      (
        rust_pkg
      )
      openssl
      pkg-config
      eza
      fd
    ];

    RUST_BACKTRACE = 1;
    RUST_SRC_PATH = "${rust_pkg}/lib/rustlib/src/rust/library";
  }

Enter the shell:

nix-shell

Launch RA:

rust-analyzer diagnostics .

You will have the following errors:

processing crate: print_all_items_driver, module: /print-all-items/src/bin/print-all-items-driver.rs
processing crate: cargo_print_all_items, module: /print-all-items/src/bin/cargo-print-all-items.rs
processing crate: print_all_items, module: /print-all-items/src/lib.rs
Diagnostic { code: RustcHardError("unresolved-extern-crate"), message: "unresolved extern crate", range: FileRange { file_id: FileId(11), range: 98..124 }, severity: Error, unused: false, experimental: false, fixes: None, main_node: Some(InFileWrapper { file_id: FileId(11), value: SyntaxNodePtr { kind: EXTERN_CRATE, range: 98..124 } }) }
Diagnostic { code: RustcHardError("unresolved-extern-crate"), message: "unresolved extern crate", range: FileRange { file_id: FileId(11), range: 125..154 }, severity: Error, unused: false, experimental: false, fixes: None, main_node: Some(InFileWrapper { file_id: FileId(11), value: SyntaxNodePtr { kind: EXTERN_CRATE, range: 125..154 } }) }
Diagnostic { code: RustcHardError("unresolved-extern-crate"), message: "unresolved extern crate", range: FileRange { file_id: FileId(11), range: 155..181 }, severity: Error, unused: false, experimental: false, fixes: None, main_node: Some(InFileWrapper { file_id: FileId(11), value: SyntaxNodePtr { kind: EXTERN_CRATE, range: 155..181 } }) }
Diagnostic { code: RustcHardError("unresolved-extern-crate"), message: "unresolved extern crate", range: FileRange { file_id: FileId(11), range: 182..209 }, severity: Error, unused: false, experimental: false, fixes: None, main_node: Some(InFileWrapper { file_id: FileId(11), value: SyntaxNodePtr { kind: EXTERN_CRATE, range: 182..209 } }) }

diagnostic scan complete

Error: diagnostic error detected

Stack backtrace:
   0: <anyhow::Error>::msg::<&str>
   1: std::sys_common::backtrace::__rust_begin_short_backtrace::<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>
   2: <<std::thread::Builder>::spawn_unchecked_<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#2} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
   3: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/d84b9037541f45dc2c52a41d723265af211c0497/library/alloc/src/boxed.rs:2022:9
   4: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/d84b9037541f45dc2c52a41d723265af211c0497/library/alloc/src/boxed.rs:2022:9
   5: std::sys::pal::unix::thread::Thread::new::thread_start
             at /rustc/d84b9037541f45dc2c52a41d723265af211c0497/library/std/src/sys/pal/unix/thread.rs:108:17
   6: start_thread
   7: __GI___clone3

See https://github.com/cognitive-engineering-lab/rustc_plugin/issues/26 for additional information.

Reproduce the report in the rustc_plugin example, using shell.nix and the print-all-items Cargo.toml and src/bin files. Start with the rust-analyzer diagnostics entry point and compare its handling of the nightly toolchain and extern crates on NixOS. Done means the example no longer reports false unresolved-extern-crate diagnostics and the diagnostics scan completes successfully.