The old logic flow had the structure
if ( … ) {
if ( … ) {
…
} else {
…
}
} else {
…
}
which is quite hard to follow in Nix. Instead we ensure that no if
expression is inside a then branch.
This change is zero rebuild, as no logic was changed.
- `toRustTarget` and friends pulled out from rust tools into rust
library. Since they don't depend on any packages they can be more
widely useable.
- `build-rust-package` gets its own directory
- `fetch-cargo-tarball` gets its own directory
