anchor.diff:        "--with-separate-debug-dir=/run/current-system/sw/lib/debug"
       ]
       ++ optional (target != null) "--target=${target.config}"
  +    ++ optional multitarget "--enable-targets=all"
       ++ optional (elem stdenv.system platforms.cygwin) "--without-python";
   
     crossAttrs = {
  
positive.code:     configureFlags = with stdenv.lib;
        [ "--with-gmp=${gmp.crossDrv}" "--with-mpfr=${mpfr.crossDrv}" "--with-system-readline"
          "--with-system-zlib" "--with-expat" "--with-libexpat-prefix=${expat.crossDrv}" "--without-python"
        ] ++ optional (target != null) "--target=${target.config}";
    };
  
    postInstall =
  
negative.code: , python ? null
  , guile ? null
  , target ? null
  # Support all known targets in one gdb binary.
  , multitarget ? false
  # Additional dependencies for GNU/Hurd.
  , mig ? null, hurd ? null
  
  