When building a workspace, cargo will report that multiple packages link to a native library when it should not.

[0xc0deface]

Problem

Steps
See test repo here for example.
https://github.com/0xc0deface/cargo_workspace_issue

1. Make a project with two libs, one (lib1) should depend on the other (lib2)
2. Make lib1 link a native library. i did this by adding the the diesel crate with the sqlite feature.
3. Make lib2 link the same native library, but only in its dev-dependencies. i did this using the sqlite crate with default-features off, then on for the dev-dependencies.

This will result in cargo build and cargo test not working due to

error: multiple packages link to native library `sqlite3`, but a native library can be linked only once

however if you build and test the libs seperately you will not get any errors suggesting there is actually no problem, and the error message is incorrect.

Possible Solution(s)

Notes

Output of cargo version: cargo 1.45.0 (744bd1fbb 2020-06-15)

[0xc0deface]

Cargo should be able to work this out itself, however a workaround for this issue is to put this build.rs file in lib2:

fn main()
{
	pkg_config::Config::new().probe("sqlite3").unwrap();
	println!("cargo:rerun-if-changed=build.rs");
}

and to comment out these lines from Cargo.toml in lib2:

[dev-dependencies]
sqlite = { version="0.25.3", default-features = true }

[ehuss]

Thanks for the report! In this particular case, this is a consequence of feature unification. Running with -Zfeatures=all breaks the restriction (#8088), though this is only because it is a post-resolver "links" check.

I'm consolidating links collisions in workspaces in #7880, so I am going to close in favor of that.