Code change:
<del> { lib, stdenv, fetchFromGitHub, callPackage, makeWrapper , clang, llvm, which, libcgroup }: let afl-qemu = callPackage ./qemu.nix { inherit afl; }; qemu-exe-name = if stdenv.hostPlatform.system == "x86_64-linux" then "qemu-x86_64" else if stdenv.hostPlatform.system == "i686-linux" then "qemu-i386" else throw "afl: no support for ${stdenv.hostPlatform.system}!"; afl = stdenv.mkDerivation rec { pname = "afl"; version = "2.57b"; src = fetchFromGitHub { owner = "google"; repo = pname; rev = "v${version}"; sha256 = "0fqj3g6ds1f21kxz7m9mc1fspi9r4jg9jcmi60inwxijrc5ncvr6"; }; enableParallelBuilding = true; # Note: libcgroup isn't needed for building, just for the afl-cgroup # script. nativeBuildInputs = [ makeWrapper which llvm.dev ]; buildInputs = [ llvm ]; makeFlags = [ "PREFIX=$(out)" ]; postBuild = '' make -C llvm_mode $makeFlags -j$NIX_BUILD_CORES ''; postInstall = '' # Install the custom QEMU emulator for binary blob fuzzing. cp ${afl-qemu}/bin/${qemu-exe-name} $out/bin/afl-qemu-trace # Install the cgroups wrapper for asan-based fuzzing. cp experimental/asan_cgroups/limit_memory.sh $out/bin/afl-cgroup chmod +x $out/bin/afl-cgroup substituteInPlace $out/bin/afl-cgroup  --replace "cgcreate" "${libcgroup}/bin/cgcreate"  --replace "cgexec"   "${libcgroup}/bin/cgexec"  --replace "cgdelete" "${libcgroup}/bin/cgdelete" # Patch shebangs before wrapping patchShebangs $out/bin # Wrap afl-clang-fast(++) with a *different* AFL_PATH, because it # has totally different semantics in that case(?) - and also set a # proper AFL_CC and AFL_CXX so we don't pick up the wrong one out # of $PATH. # first though we need to replace the afl-clang-fast++ symlink with # a real copy to prevent wrapProgram skipping the symlink and confusing # nix's cc wrapper rm $out/bin/afl-clang-fast++ cp $out/bin/afl-clang-fast $out/bin/afl-clang-fast++ for x in $out/bin/afl-clang-fast $out/bin/afl-clang-fast++; do wrapProgram $x  --prefix AFL_PATH : "$out/lib/afl"  --run 'export AFL_CC=''${AFL_CC:-${clang}/bin/clang} AFL_CXX=''${AFL_CXX:-${clang}/bin/clang++}' done ''; passthru.qemu = afl-qemu; meta = { description = "Powerful fuzzer via genetic algorithms and instrumentation"; longDescription = '' American fuzzy lop is a fuzzer that employs a novel type of compile-time instrumentation and genetic algorithms to automatically discover clean, interesting test cases that trigger new internal states in the targeted binary. This substantially improves the functional coverage for the fuzzed code. The compact synthesized corpora produced by the tool are also useful for seeding other, more labor or resource-intensive testing regimes down the road. ''; homepage    = "https://lcamtuf.coredump.cx/afl/"; license     = lib.licenses.asl20; platforms   = ["x86_64-linux" "i686-linux"]; maintainers = with lib.maintainers; [ thoughtpolice ris ]; }; }; in afl </del>

Related discussion:
text: Steps to reproduce the behavior: afl <!-- Please @ people who are in the list of the offending package or module. If in doubt, check for whoever last touched something. -- Please run and paste the result. Add a :+1: [reaction] to [issues you find important]. [reaction]: [issues you find important]:
If you are planing to open a PR, you don't need to create an issue first.
I wasn't sure, thanks for clarification