anchor.diff:    # Work around <http://bugs.gnu.org/14201>.
     SHELL = "/bin/sh";
     CONFIG_SHELL = "/bin/sh";
  -}))
  +})
  
positive.code:       processing.
      '';
    };
  }
  
  //
  
  (stdenv.lib.optionalAttrs stdenv.isSunOS {
    # TODO: Move me above.
    configureFlags =
      [
        # Make sure the right <gmp.h> is found, and not the incompatible
        # /usr/include/mp.h from OpenSolaris.  See
        # <https://lists.gnu.org/archive/html/hydra-users/2012-08/msg00000.html>
        # for details.
        "--with-libgmp-prefix=${gmp.dev}"
  
        # Same for these (?).
        "--with-libreadline-prefix=${readline.dev}"
        "--with-libunistring-prefix=${libunistring}"
  
        # See below.
        "--without-threads"
      ];
  })
  
  //
  
negative.code:   # don't have "libgcc_s.so.1" on darwin
    LDFLAGS = stdenv.lib.optionalString (!stdenv.isDarwin) "-lgcc_s";
  
    configureFlags = [ "--with-libreadline-prefix" ]
      ++ stdenv.lib.optionals stdenv.isSunOS [
        # Make sure the right <gmp.h> is found, and not the incompatible
        # /usr/include/mp.h from OpenSolaris.  See
        # <https://lists.gnu.org/archive/html/hydra-users/2012-08/msg00000.html>
        # for details.
        "--with-libgmp-prefix=${gmp.dev}"
  
        # Same for these (?).
        "--with-libreadline-prefix=${readline.dev}"
        "--with-libunistring-prefix=${libunistring}"
  
        # See below.
        "--without-threads"
      ];
  
    postInstall = ''
      wrapProgram $out/bin/guile-snarf --prefix PATH : "${gawk}/bin"
  