Unneeded dependency compiled

help
1

I have a workspace with several packages.
The root Cargo.toml lists rustls under [workspace.dependencies]

Only one of the packages in the codebase is directly dependent on rustls.
It uses this to set up a default crypto provider: rustls::crypto::aws_lc_rs::default_provider()

What I can't explain (and this is causing me problems whilst cross-compiling), is that when I use "cargo build --bin" for a binary in another package, which, according to "cargo tree", has no dependency on aws-lc-rs or rustls whatsoever, it will still compile the aws crates!
In particular, it is the file cc_builder.rs in the source code of aws-lc-rs that is failing during cross compilation.

I know how to fork from aws-lc-rs and use "[patch]" in the root Cargo.toml to prevent running into the cross-compilation error, but I'd rather have an explanation as to why aws-lc-rs is compiled for a binary that doesn't depend on it?

I'm using cargo 1.91.1

2

Does this package that directly depends on rustls (or any other package that directly or indirectly depends on rustls) also get compiled?

3

No, the package that actually depends on rustls doesn't get compiled when using "cargo build --bin "

4

Do you have a reproducer that you can share?

5

My bad, after some searching I found the answers I was looking for!

First of all, I have found that there really is a dependency, I just couldn't see it with cargo tree. What I needed was cargo tree --workspace --all-features --no-dedupe.

Secondly, I found a way to get the rustls compiled without the need for aws-lc-rs.

So all is well, I guess the only question that remains is: could I alternatively have included rustls in our source code twice, once with aws-lc-rs and once without?