Unfortunate, but expected. On that note, would there be any breakage loading multiple Rust .so's with differing compiler/stdlib versions into the same process? This is one of my main concerns about the lack of ABI stability and the static-linking-first design of Rust. With C++ at the very least I know Red Hat isn't going to break the ABI within a major release, but the Rust 1.21 packages are already in epel-testing.