" can't find crate for 'wasmtime-component-macro' " Error while trying to build a crate with wasmtime

help
1

I'm not sure what's causing this, and I have noticed that this happens with other unrelated crates as well where it will not be able to find a macro-related crate even though that crate does show up in the build log. I've also tried adding said crate as a dependency in my Cargo.toml, but still no dice.

Is there something I don't know about cargo that is causing this? I'm also using NixOS, could the non-standard filesystem hierarchy be causing some issues? I'd love to solve this problem on my own but I really don't know where to begin. Any and all guidance would be appreciated

EDIT: Below is the output of cargo build -p wasmtime on my machine:

   Compiling wasmtime v30.0.2
error[E0463]: can't find crate for `wasmtime_component_macro`
   --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/mod.rs:408:9
    |
408 | pub use wasmtime_component_macro::bindgen;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error[E0463]: can't find crate for `wasmtime_component_macro`
   --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/mod.rs:550:9
    |
550 | pub use wasmtime_component_macro::ComponentType;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error[E0463]: can't find crate for `wasmtime_component_macro`
   --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/mod.rs:578:9
    |
578 | pub use wasmtime_component_macro::Lift;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error[E0463]: can't find crate for `wasmtime_component_macro`
   --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/mod.rs:606:9
    |
606 | pub use wasmtime_component_macro::Lower;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error[E0463]: can't find crate for `wasmtime_component_macro`
   --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/mod.rs:665:9
    |
665 | pub use wasmtime_component_macro::flags;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error[E0432]: unresolved imports `crate::component::ComponentType`, `crate::component::Lift`, `crate::component::Lower`, `crate::component::Lift`, `crate::component::Lower`, `crate::component::Lift`, `crate::component::Lower`, `crate::component::ComponentType`, `crate::component::Lift`, `crate::component::Lower`
 --> /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/func/host.rs:4:44
  |
4 | use crate::component::{ComponentNamedList, ComponentType, Lift, Lower, Val};
  |                                            ^^^^^^^^^^^^^  ^^^^  ^^^^^
  |
 ::: /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/instance.rs:4:64
  |
4 |     Component, ComponentExportIndex, ComponentNamedList, Func, Lift, Lower, ResourceType, TypedFunc,
  |                                                                ^^^^  ^^^^^
  |
 ::: /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/linker.rs:6:59
  |
6 |     Component, ComponentNamedList, Instance, InstancePre, Lift, Lower, ResourceType, Val,
  |                                                           ^^^^  ^^^^^
  |
 ::: /home/bailor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-30.0.2/src/runtime/component/resources.rs:3:24
  |
3 | use crate::component::{ComponentType, Lift, Lower};
  |                        ^^^^^^^^^^^^^  ^^^^  ^^^^^

Some errors have detailed explanations: E0432, E0463.
For more information about an error, try `rustc --explain E0432`.
error: could not compile `wasmtime` (lib) due to 6 previous errors
2

What are the exact steps you took that lead to the error message you posted?

3

Here is a minimal reproducible example. Firstly, I am using NixOS 23.11 but my flake for the project uses nixpkgs-unstable. I elected to use a flake because the project I'm building has some C-library dependencies and since I'm on NixOS that's the preferred way of managing C dependencies. Below is a minimal flake I used to reproduce the issue.

{
	description = "Minimal Reproducible Example Flake";
	inputs = {
		nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
	};
	outputs = { self, nixpkgs }:  
    let 
        pkgs = nixpkgs.legacyPackages.x86_64-linux;
    in
    {
        devShell.x86_64-linux = pkgs.mkShell {
            shellHook = "$SHELL; exit"; # I use zsh, nix-shell won't use zsh by default
            nativeBuildInputs = with pkgs; [
                rustup
            ];
        };
	};
}

In the directory where that flake was created I run nix develop to add rustup to my path, then cargo init . to create a new crate. cargo add wasmtime and then cargo build. The output of the build is the same as the output in my original post. Changing toolchains doesn't make a difference.

4

I'm sorry I can't help you much. I can only say that wasmtime 30.0.2 and 31 both compile linux, so I think it's related to the nix config.

5

I've fixed the issue, and it was related to nix. The way nix patches binaries doesn't jive well with rustup. For what reason I'm not sure, and sadly I don't really have time to track down that reason. However the simple way I fixed this while still using nix to manage everything is to just use a different version of rustup than the one provided by nixpkgs. I've tried and succeeded in compiling wasmtime with both a version from devenv and one from a rust overlay created a nix user. (https://github.com/oxalica/rust-overlay)