Loom should be dev dependency

[JordiPolo]

Bytes brings as dependency loom which itself brings a lot of stuff. This is very surprising because loom is a testing utility.

[seanmonstar]

It's listed only for cfg(loom).

[Ralith]

Does that actually work?

[JordiPolo]

I'm getting bytes via reqwest and tokio, no extra configuration or anything and I do get loom

[jplatte]

@JordiPolo Can't reproduce. Creating a dummy project and adding tokio with features = ["full"] + reqwest, then running cargo tree, does not turn up loom.

[JordiPolo]

Maybe is my ignorance of how Cargo works then.
Indeed cargo tree does not show loom but it is in the Cargo.lock file as dependency of bytes. I thought that was enough for the project to compile it.

[[package]]
name = "bytes"
version = "0.5.5"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "loom 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
]

[jplatte]

With my dummy project it also wasn't compiled. I'm pretty sure the lockfile is target-independent, so compiling the same project for different targets doesn't change the lockfile back and forth (if it would that would be very annoying for applications that keep the lockfile in source control).

[jplatte]

crates.io could really use some UI for target-specific dependencies though...

[JordiPolo]

Yeah, just looking at the files in my repo I do not have enough information to know if I am going to compile this into my production application which can be scary.
Anyways, this turned out to not be an issue, thank you for looking into it!

[benma]

Please reopen this issue. It is also a problem when using cargo vendor, which pulls in a ton of crates that should not be there.

[jplatte]

Seems like something that should be handled as an option in cargo vendor, like cargo metadatas --filter-platform or cargo trees --target.

[benma]

Seems like something that should be handled as an option in cargo vendor, like cargo metadatas --filter-platform or cargo trees --target.

Would be nice, but I don't think it exists? See also https://www.reddit.com/r/rust/comments/8plauq/dont_vendor_deps_i_dont_need/

[jplatte]

Doesn't look like it but still, if the extra stuff being downloaded is an issue for you, you should probably try to get cargo fixed rather than having bytes work around it. The main issue seems to be rust-lang/cargo#4544.

[benma]

I agree in principle, but in practice it could take years to fix it in cargo. Maybe there is a simple workaround in bytes that could help in the meantime.

In any case, the solution I went for in the end is to fork bytes, remove the loom dep, and patch it in with a [patch] section in my Cargo.toml. It's not great, especially as I need to maintain the fork and keep it in sync with new releases.

[carllerche]

Switching it to a dev-dependency should be a trivial PR. Anyone here should feel free to submit it.