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Feature to declare that a crate never can be "unused" when mentioned in extern crate #44827
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I agree. Currently I think you should be able to simulate this by using an allocator, but well it's destructive.
Sorry no I don't.
I only know one particular kind of false positive: usage of -sys crates just for linkage, such as
git2->openssh.I haven't dig into your case, but I'm not sure why you need to put it in all the tests. What's your linkage model?
@ishitatsuyuki My use case has some components, including the tests, written in C, while others are written in Rust. For the tests, I took the original C tests and integrated them as cargo tests, so that I can run them using the superior cargo tooling (multiple threads, better output, etc.).
For the -sys crate, I don't really run bindgen, and in fact the C component calls into the Rust component. I try to avoid calling the other way round where possible.
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on Oct 19, 2018
Recently we got the
unused_extern_cratelint (#42588). It still has an issue though with false positives around crates that contain natively linkable stuff, like-syscrates for example. The issue has been discussed in PR #42588 already, however it has been dismissed, because its a similar situation to thebad_stylelint. There is a difference though, which is that you disable the lint at the declaration site, not the use site.The difference became a very visible in my
werkcrate. I was having a bunch of integration tests each only linking to my werk crate to get the native API it offers, and I had to add#![allow(unused_extern_crate)]to every single integration test, while I had to allow the bad_style lint only in once place. That's not nice!It would be cool if the false positive doesn't get fixed, there at least was a feature where I could do something with the werk crate so that the "unused"
extern crate werkdoesn't become a warning. This is not just interesting for my particular use case which is probably a bit niche compared to mainstream. Its also interesting if you look into the future (#44660), where#[allow(unused_extern_crate)] extern crate foo;becomes legacy, and you'd probably have to think about either having to add a way to disable the lint in Cargo.toml, or the only way to disable the lint will be globally for all dependencies by doing#![allow(unused_extern_crate)]in {lib,main}.rs. I think what I suggest is better than those two alternatives.cc @aturon
cc @ishitatsuyuki