Package ‘dmd-2.079.0’ in /var/lib/gc-of-borg/nix-test-rs-30/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/grahamc-aarch64-community-30/pkgs/development/compilers/dmd/default.nix:236 is not supported on ‘aarch64-linux’, refusing to evaluate.

a) For `nixos-rebuild` you can set
  { nixpkgs.config.allowBroken = true; }
in configuration.nix to override this.

b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
  { allowBroken = true; }
to ~/.config/nixpkgs/config.nix.

Edit source/app.d to start your project.
installing
post-installation fixup
strip is /nix/store/4sdh09gmvl15cy0zb6i7mbvxh5syz206-cctools-binutils-darwin/bin/strip
patching script interpreter paths in /nix/store/df25k9rb95ww3ac0b38mjpwzx983lvqi-dubUnittests-1.8.0
building '/nix/store/kxkzs4sz7wcmr1658xn3n7qd6bsccr6q-dub-1.8.0.drv'...
installing
/nix/store/8rw80f2ljr0b685f77wg4123lccnn5va-dmd-2.079.0
/nix/store/cq9pvjrbxf03m1x36ir5sbqprzjgll2n-dtools-2.079.0
/nix/store/zbb0jxyi8ka61k0zng2jiszgsx0l5zj2-dub-1.8.0

post-installation fixup
shrinking RPATHs of ELF executables and libraries in /nix/store/863d2yjij6q2vg9s2y9bi3p75xpwhm2b-dubUnittests-1.8.0
strip is /nix/store/b0zlxla7dmy1iwc3g459rjznx59797xy-binutils-2.28.1/bin/strip
patching script interpreter paths in /nix/store/863d2yjij6q2vg9s2y9bi3p75xpwhm2b-dubUnittests-1.8.0
checking for references to /tmp/nix-build-dubUnittests-1.8.0.drv-0 in /nix/store/863d2yjij6q2vg9s2y9bi3p75xpwhm2b-dubUnittests-1.8.0...
building path(s) ‘/nix/store/sapbppdg7l1d4a1s8c2yavzk2zq3hrra-dub-1.8.0’
installing
/nix/store/sbnbpkab14vx6ci37529bqjqq9as3cj4-dmd-2.079.0
/nix/store/9s2xd62i2c8hj73in7kr5byzvj7lr0px-dtools-2.079.0
/nix/store/sapbppdg7l1d4a1s8c2yavzk2zq3hrra-dub-1.8.0