Merge pull request #237858 from tie/rubygems-pg

  };

  pg = attrs: {

    buildFlags = [

      "--with-pg-config=${postgresql}/bin/pg_config"

    ];

    # Force pkg-config lookup for libpq.

    # See https://github.com/ged/ruby-pg/blob/6629dec6656f7ca27619e4675b45225d9e422112/ext/extconf.rb#L34-L55

    #

    # Note that setting --with-pg-config=${postgresql}/bin/pg_config would add

    # an unnecessary reference to the entire postgresql package.

    buildFlags = [ "--with-pg-config=ignore" ];

    nativeBuildInputs = [ pkg-config ];

    buildInputs = [ postgresql ];

  };

  psych = attrs: {