title: __func__ or __FUNCTION__ or manual const char* id?
body: <p>I'm wondering how widely are <code>__func__</code> (part of C99, but I'm compiling as C89) and <code>__FUNCTION__</code> supported.</p>
  
  <p>I have an old code base that is mostly using manual <code>const char* id;</code> variables that are then passed to various (mostly logging) functions. I would like to get rid of this and move the function name into a macro.</p>