This crate offers the ability to build a rustc sysroot from source. You can think of it as a very
lightweight version of [xargo] (which was a useful source for information on how to do this), or a
version of [cargo -Zbuild-std
] that builds a sysroot rather than building the standard library for
the current crate.
Building the sysroot from source is useful for tools like [Miri] and [cargo-careful] that need the standard library to be built with different flags. Building a sysroot from different sources is not a goal of this crate.