pfr I noticed you have RUST_TYPE= src in your mk.conf. What does this do exactly and should I also add it to mine if I intend to build many rust packages?
Yes, I wrote this above. If, you are planning on building rust packages, you should set the option.
There are two rust packages in tree, lang/rust and lang/rust-bin. The former is compiled from the source code and, the later is a way to distribute upstream Rust compiled binaries or, for archs where these are not available, to distribute the binaries he@ kindly provides for those.
Now, this has nothing to do with your build failure. I don't know what is going on, maybe the download of the tarball was corrupted.
pfr What does this do exactly
It tells the system which rust package to use by default when building other packages.
pfr What exactly was the cause of the problem?
See the commit message
When a dependency is not buildlink included, header files will be hidden from the compiler.
