anchor.diff:    # LTO is done using clang and lld on Linux.
     # Darwin needs to use the default linker as lld is not supported (yet?):
     #   https://bugzilla.mozilla.org/show_bug.cgi?id=1538724
  -  # elf-hack is broken when using clang:
  +  # elf-hack is broken when using clang+lld:
     #   https://bugzilla.mozilla.org/show_bug.cgi?id=1482204
     ++ lib.optionals ltoSupport [
       "--enable-lto"
  
positive.code: 
  assert stdenv.cc.libc or null != null;
  assert pipewireSupport -> !waylandSupport || !webrtcSupport -> throw "pipewireSupport requires both wayland and webrtc support.";
  
  let
    flag = tf: x: [(if tf then "--enable-${x}" else "--disable-${x}")];
  
negative.code:             then "/Applications/${binaryNameCapitalized}.app/Contents/MacOS"
              else "/bin";
  
    # Darwin's stdenv provides the default llvmPackages version, match that since
    # clang LTO on Darwin is broken so the stdenv is not being changed.
    llvmPackages = if stdenv.isDarwin
                   then buildPackages.llvmPackages
                   else buildPackages.llvmPackages_10;
  
    # When LTO for Darwin is fixed, the following will need updating as lld
    # doesn't work on it. For now it is fine since ltoSupport implies no Darwin.
    buildStdenv = if ltoSupport
                  then overrideCC stdenv llvmPackages.lldClang
                  else stdenv;
  