opt_nosave manage-submodules 1 "let the build manage the git submodules"
opt_nosave clang 0 "prefer clang to gcc for building the runtime"
opt_nosave jemalloc 1 "build liballoc with jemalloc"
-opt elf-tls 1 "elf thread local storage on platforms where supported"
opt full-bootstrap 0 "build three compilers instead of two"
opt extended 0 "build an extended rust tool set"