8.3 GNU Programs: how to avoid nana sometimes

Imagine you¹ are building a GNU program. Ideally it should run on systems without any other software including GCC, GDB and even Nana.

To achieve this noble goal you can provide your configure script with a `--without-nana'<sup>2</sup> flag which then `#define's' `WITHOUT_NANA'. You should also use the `VL' macro rather than `L' macro since `L' takes a variable number of arguments and will break non GNU C preprocessors.

     int half(int n) {
       /* Don't use L(...) since it takes a variable number of args! */
       VL(("hello world = %d\n", 10)); /* Note the doubled (( */
       ...;
     }