I'm rewriting C source to Ada and on some places there is conditional compilation for handling different platforms, such as windows vs posix, DEBUG, or architecture. For what I can tell neither Ada nor GPR has the notion of conditional compilation.

What's the Ada way of handling it?

Example:

/* Determine if a process is alive. */
#ifndef _WIN32
   if (kill(pid, 0) && errno == ESRCH)
      return 0; /* pid does not exist */
#else
   HANDLE h;
   if ((h = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, (DWORD)pid)) == 0)
      return 0; /* pid does not exist */
   CloseHandle(h);
#endif
   return 1;

Is there a warning option switch that will identify spec-level procedures, functions, or variables that are not called or referenced anywhere? I've tried the switches below without luck.

This is what I'm currently using: -gnatwfilmopuvz -- m turn on warnings for variable assigned but not read -- u turn on warnings for unused entity -- v turn on warnings for unassigned variable

When I move unused variables from the spec to the body, the compiler correctly identifies them as not referenced. I would like to understand why the compiler won't identify unused code in the spec, and if there is a way to get it to do so. An excessive number of warnings isn't a concern, because I use the filter field in gnat studio to only look at a few files at a time, and I can easily filter to ignore library packages.

Any help is very appreciated.