bertptrs [1] filed a deletion request for rust-src [2]: The files installed by this package are already available under /usr/lib/rustlib/src/rust/src/ when using extra/rust, and are more easily available when using community/rustup. As it stands, this package provides no other use and can safely be deleted.
[1] https://aur.archlinux.org/account/bertptrs/ [2] https://aur.archlinux.org/pkgbase/rust-src/
