These are my tests for this PR: https://github.com/NixOS/nixpkgs/pull/18386

nixpkgs-pr-test.nix

rec {
  myNixpkgsFunc = import ./nixpkgs;
  myNixpkgs = myNixpkgsFunc {};

  baseNixpkgsFunc = import ((import <nixpkgs> { }).fetchFromGitHub {
    owner = "NixOS";
    repo = "nixpkgs";
    rev = "d4eac0278ca188aa236b6a7f0fbb15f8ee4273d0";
    sha256 = "0mpx6bjvix7dfmgn6a2chmmicamz9v941fki0lgzfk2gw90fqg6w";
  });
  baseNixpkgs = baseNixpkgsFunc {};

  myTestsPass = (import ./nixpkgs/test/cross_system.nix).testsPass;

  gcc6Same = myNixpkgs.gcc6 == baseNixpkgs.gcc6;
  gcc5Same = myNixpkgs.gcc5 == baseNixpkgs.gcc5;
  gcc49Same = myNixpkgs.gcc49 == baseNixpkgs.gcc49;
  gcc48Same = myNixpkgs.gcc48 == baseNixpkgs.gcc48;
  gcc45Same = myNixpkgs.gcc45 == baseNixpkgs.gcc45;
  gccSame = gcc6Same && gcc5Same && gcc49Same && gcc45Same;
  libtoolSame = myNixpkgs.libtool == baseNixpkgs.libtool;
  guileSame = myNixpkgs.guile == baseNixpkgs.guile;

  testsPass = myTestsPass && gccSame && libtoolSame && guileSame;

  derivations = rec {
    recurseForDerivations = assert testsPass; true;

    rpiCrossSystem = {
      config = "armv6l-unknown-linux-gnueabi";
      bigEndian = false;
      arch = "arm";
      float = "hard";
      fpu = "vfp";
      withTLS = true;
      libc = "glibc";
      platform = myNixpkgs.platforms.raspberrypi;
      openssl.system = "linux-generic32";
      gcc = {
        arch = "armv6";
        fpu = "vfp";
        float = "softfp";
        abi = "aapcs-linux";
      };
    };
    rpiPkgs = myNixpkgsFunc { crossSystem = rpiCrossSystem; };
    rpiHello = rpiPkgs.hello.crossDrv;

    rpiPkgsBase = baseNixpkgsFunc { crossSystem = rpiCrossSystem; };
    rpiHelloBase = rpiPkgsBase.hello.crossDrv;

    releaseCross = import ./nixpkgs/pkgs/top-level/release-cross.nix;

    # These are all the jobs from
    # https://hydra.nixos.org/eval/1291742#tabs-still-succeed
    bootstrapTools = {
      recurseForDerivations = true;
      armv5tel = releaseCross.bootstrapTools.armv5tel;
      armv6l = releaseCross.bootstrapTools.armv6l;
      armv7l = releaseCross.bootstrapTools.armv7l;
    };

    crossMingw32 = {
      recurseForDerivations = true;
      boehmgc = releaseCross.crossMingw32.boehmgc.crossDrv {};
      gmp = releaseCross.crossMingw32.gmp.crossDrv {};
      libffi = releaseCross.crossMingw32.libffi.crossDrv {};
      libtool = releaseCross.crossMingw32.libtool.crossDrv {};
      libunistring = releaseCross.crossMingw32.libunistring.crossDrv {};
    };

    crossMingwW64 = {
      recurseForDerivations = true;
      boehmgc = releaseCross.crossMingwW64.boehmgc.crossDrv {};
      gmp = releaseCross.crossMingwW64.gmp.crossDrv {};
      libffi = releaseCross.crossMingwW64.libffi.crossDrv {};
      libtool = releaseCross.crossMingwW64.libtool.crossDrv {};
      libunistring = releaseCross.crossMingwW64.libunistring.crossDrv {};
    };

    crossShevaplugLinux = {
      recurseForDerivations = true;
      bison = releaseCross.crossSheevaplugLinux.bison.crossDrv {};
      busybox = releaseCross.crossSheevaplugLinux.busybox.crossDrv {};
      coreutils = releaseCross.crossSheevaplugLinux.coreutils.crossDrv {};
      dropbear = releaseCross.crossSheevaplugLinux.dropbear.crossDrv {};
      gcc = releaseCross.crossSheevaplugLinux.gccCrossStageFinal {};
    };

    fuloongminipc = {
      recurseForDerivations = true;
      coreutils = releaseCross.fuloongminipc.coreutils.crossDrv {};
      ed = releaseCross.fuloongminipc.ed.crossDrv {};
      patch = releaseCross.fuloongminipc.patch.crossDrv {};
    };

    rpi = {
      recurseForDerivations = true;
      binutils = releaseCross.rpi.binutils.crossDrv {};
      coreutils = releaseCross.rpi.coreutils.crossDrv {};
      ddrescue = releaseCross.rpi.ddrescue.crossDrv {};
      ed = releaseCross.rpi.ed.crossDrv {};
      lynx = releaseCross.rpi.lynx.crossDrv {};
      mpg123 = releaseCross.rpi.mpg123.crossDrv {};
      patch = releaseCross.rpi.patch.crossDrv {};
      patchelf = releaseCross.rpi.patchelf.crossDrv {};
      unzip = releaseCross.rpi.unzip.crossDrv {};
      vim = releaseCross.rpi.vim.crossDrv {};
    };
  };
}