Unresolved import for a crate on crates.io

help
1

I have published a crate (serial_traits), and I want to use it for my other projects.
However, if I do use serial_traits, I get red underlines with this hover popup:

unresolved import `serial_traits`
if you wanted to use a crate named `serial_traits`, use `cargo add serial_traits` to add it to your `Cargo.toml`

The problem is that this error message is contradicting Cargo.toml:

[package]
name = "common"
version = "0.1.0"
edition = "2024"

[dependencies]
glam = "0.30.4"
serial_traits = "1.1.0"

This is a workplace, and the common crate with its dependencies was initialized with the following commands:

cargo new common --lib
cargo add glam
cargo add serial_traits

An extra thing I have done is that I added net_structs.rs (where I am trying to use serial_traits in), which I have let VSCode know the existence of by putting pub mod net_structs; in lib.rs.

I saw that others have had the same or similar problem and solved it (like this one) and I tried their solutions.
Their suggestions did not work.

Something I have noticed is that occasionally, after changing edition (trying other editions), rust-analyzer would temporarily accept that serial_traits exists.
And yet, cargo test and cargo build would still give this output:

error[E0432]: unresolved import `serial_traits`
>cargo test
   Compiling glam v0.30.4
   Compiling serial_traits v1.1.0
   Compiling common v0.1.0 (C:\Users\[me]\Projects\Git Repos\wasm_2dtestmpgame\common)
error[E0432]: unresolved import `serial_traits`
 --> common\src\net_structs.rs:2:5
  |
2 | use serial_traits::Serializable;
  |     ^^^^^^^^^^^^^ use of unresolved module or unlinked crate `serial_traits`
  |
  = help: if you wanted to use a crate named `serial_traits`, use `cargo add serial_traits` to add it to your `Cargo.toml`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `common` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...

The cargo build and cargo test commands were ran after cargo cleaning, and it shows that serial_traits successfully compiles.

Other things I have tried out, repeatedly, in arbitrary orders:

  • Restarting VSCode
  • Closing and reopening Command Prompt
  • cargo clean
  • Removing and readding serial_traits
  • rustup update
  • Directly copy and pasting the crate name from and to several places in case I wrote it wrong

Is there something I am missing? Maybe during the publishing process?
I have no idea what other options even exist, and I don't want to clone copies of my crate into each project I want to use it in.

2

when you do that and run cargo build you should also get a warning:

warning: The package `serial_traits` provides no linkable target. The compiler might raise an error while compiling `common`. Consider adding 'dylib' or 'rlib' to key `crate-type` in `serial_traits`'s Cargo.toml. This warning might turn into a hard error in the future.

That's because in your code you defined it as a crate-type = ["cdylib"]:

I don't know why you did that, but you probably just want ["lib"] there. Or leave it off completely.

1 Like
3

The published source code for your library contains:

[lib]
crate-type = ["cdylib"]

This makes it ineligible for use as a Rust dependency, and only usable as a dynamically-loaded library for non-Rust programs. You should probably remove this line. (Why did you add it?)

I recommend that you should always test a library is usable as a dependency before publishing it — the easiest way to do it is with Cargo “integration tests” which are placed in the tests/ directory:

Cargo.toml
src/
    lib.rs
tests/
    my-test.rs

In tests/my-test.rs, write #[test] functions that make use of your library. (I see you have some test functions already; it may be wise to move them to tests/ to get more coverage, presuming they don't use any private items.) Then run cargo test to run those tests. This will prove that the library is in fact usable from a dependent crate.

You can also use documentation tests for the same purpose, providing examples in your library documentation that are proven to work by running them.

4

"cdylib" was the problem and it works after I changed it! thank you very much!
Though, I have no idea why I made it a cdylib ¯\_(ツ)_/¯