Cargo does in fact support out-of-tree builds, using either build.target-dir or CARGO_TARGET_DIR . See http://doc.crates.io/config.html#configuration-keys and http://doc.crates.io/environment-variables.html#environment-variables-cargo-reads . Maybe it could be made easier to find.
The extended error explanations are available online at https://doc.rust-lang.org/error-index.html , and there’s a link to that page from https://doc.rust-lang.org/ .
Filed https://github.com/rust-lang/rust/issues/35101 about the SIGTRAP.