Rust binaries essentially never dynamically link Rust libraries, mostly for the reason Manishearth said in the sibling. The decision to have different default a

Rust binaries essentially never dynamically link Rust libraries, mostly for the reason Manishearth said in the sibling. The decision to have different default allocators is because there were problems linking to Rust from C libraries which used the system allocator, because Rust previously was exclusively using jemalloc. Because Rust libraries being used in Rust projects will be statically linked currently, they will be built using jemalloc. Deploying a pure Rust project is as simple as pushing out a binary (std links to libc, so very few Rust projects are technically pure Rust, but its as good as because the system probably has libc). Also, as a rule, you don't "free" in Rust at all, and code which defines how the memory is deallocated will be defined in the same library it was allocated in. I don't know the details of what it means when two libraries using two different allocators are interacting, but I don't think its as total a conflict as if you were to try to free a pointer with the wrong allocator's free function.