Rust submission timing out, perhaps because of compilation time?

I’m trying to submit a solution to the Poker exercise in Rust. My solution uses some external crates. I’ve verified they’re allowed in the test runners. Locally, everything compiles and the tests pass. On Exercism, the tests time out. Can it be because my crates make the compilation time too long?

Here are my dependencies:

derivative = "~2"
strum = "~0.24"
strum_macros = "~0.24"
thiserror = "~1"

(I had to use tilde requirements and not submit Cargo.lock to make it accept the solution, because apparently some of the latest versions of the crates are not present on test runners.)

Without further investigation: Yes, I think your guess is spot on.

The dependencies you’re using provide proc macros relying on syn, which is known for increasing compile times significantly.

Some exercises on the Rust track suggest to use such dependencies in the exercise description and they have the online tests disabled, because basically everyone’s tests were timing out.

If the tests pass locally, I usually suggest to just mark the exercise as completed. If you want to make the online tests pass, I’m afraid you might have to drop the dependencies.