Build error because of different clang-sys/bindgen requirements

[5jqk2ymwqd]

When I tried to build a project depending on this crate I get the following error:

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

package clang-sys v0.21.2
... which is depended on by bindgen v0.31.3
... which is depended on by libffi-sys v0.6.0
... which is depended on by libffi v0.6.3
... which is depended on by mpi v0.5.2
... which is depended on by project-using-mpi v0.1.0 (file:///path/to/project-folder)
links to native library clang

package clang-sys v0.22.0
... which is depended on by bindgen v0.33.2
... which is depended on by mpi-sys v0.1.1
... which is depended on by mpi v0.5.2
... which is depended on by project-using-mpi v0.1.0 (file:///path/to/project-folder)
also links to native library clang

The project has only mpi as dependency (Cargo.toml):

[dependencies]
mpi = "*"

Maybe mpi-sys could depend on bindgen v0.31.3 (libffi-sys depends explicitly on bindgen = "0.31.3"), too. Or do you think it is better to wait for libffi-sys to update to the current bindgen?

Thanks a bunch for this crate, I am excited to try it.

[bsteinb]

Hm, that is unfortunate, I will tie down the version of bindgen that mpi-sys uses and publish a new version to crates.io.

However, I suspect that cargo is being too cautious in this situation. bindgen and through it clang-sys is a build dependency of both mpi-sys and libffi-sys, so it will be linked to their build scripts, but not to the resulting libraries, so there will not be a mix of different versions of clang-sys or the native libclang in the resulting mpi library. I will open an issue for cargo and see what the developers think about this.

Thank you for the report and the encouraging words.

Edit: I have opened an issue here: rust-lang/cargo#5237

[bsteinb]

All right, I have just released mpi-0.5.3 which should fix the issue.

[5jqk2ymwqd]

Thank you very much.

[Eh2406]

Oddly I can not reproduce, I built a new project and added

[dependencies]
mpi = "=0.5.2"

And ran cargo +nightly generate-lockfile which ran without trouble.
That error message is from the resolver that is used in generate-lockfile, and was added recently (by me) so this must be on a nightly. I wonder if an outdated lock file is involved?

[bsteinb]

Yes, this is on rustc 1.26.0-nightly (c08480fce 2018-03-23). I can confirm that cargo generate-lockfile works without reporting an error. I only run into the issue I reported when I try to cargo build.

Edit: I also deleted my Cargo.lock and ran cargo build and I am still seeing the issue.

[Eh2406]

I was wrong. This is the older error message, not the one I just added. Sorry for the crossed wires.