When jemalloc-sys builds the jemalloc native dependency, it first creates a build directory on disk, then runs make and make install, which installs a copy of the built libs into a lib directory, amongst other things. However, after the build finishes, the build directory is still kept on disk. It takes ~220 MiB on my x64 Linux, which is quite a lot! Especially considering that it can exist in multiple copies (debug/release, multiple repos using jemalloc etc.).

I think that the build.rs script should delete the build directory from disk once the compilation (make install) successfully finishes, since it shouldn't be needed anymore, and I don't think that Cargo will ever reuse it (if something relevant changes, Cargo will compile jemalloc from scratch in a different directory, AFAIK).

What do you think?