According to https://reviews.llvm.org/D96164, aarch64-darwin executables
require at least an ad hoc signature.
The build tool from the racket repo tries to sign $out/bin/racket but
errors out, because that binary already has a signature.
It is not clear yet at which stage the signature was introduced. This
patch removes the existing signature always before calling
add-ad-hoc-signature to circumvent that error.
Technically, racket compiles and packages too, but it doesn't pass all
tests yet, so the build fails.
gcc7Stdenv is GCC 7 with the MacOS-specific adaptations retained.
Building on MacOS with that works, but we should be using clang.
I'm hoping that the next person wanting to override the compiler
version in some other derivation sees that attribute and doesn't
inadvertently break a MacOS build again.
Racket without the bundled packages, such as Mr Racket.
The essential package racket-libs is included, as well as libraries
that live in collections. In particular, raco and the pkg library are
still bundled.
