The perversion of defining a macro in the expansion of another macro is orthogonal to the issue of whether or not preprocessor directives can be freely interpolated. The C/C++'s preprocessor could have allowed:

  #define MOO(define) #define x QUACK

…but they've prohibited it from working the way you might expect (and hijacked # inside macros for another purpose, which is why I was sick and used "define" as the macro parameter's name (-8 ).

I'm guessing they decided that macros defining macros was a can of worms best left unopened.

At this point I'm remembering Modula-3's pragma syntax: <* … *> to go with the Wirth (* … *) for comments. (How come everyone's happy using [ … ] for arrays in Pascal instead of (. … .), but still uses (* … *) instead of { … } for comments?) Had C used something similar, we could have avoided all this __attribute__ and __declspec nonsense for starters!

If I ever design a language in the C problem space, knowing what I know now, the pragma syntax will be something like:

void f() {
  #pragma #switch(COMPILER_VERSION) {
      RECENT_GCC:
          diagnostic push;
          diagnostic ignored "-Wuninitialized";
          break;
      MSVC:
          warning(push);
          warning(disable: C4700);
          break;
  }

  // Do some stuff...

  #pragma #switch(COMPILER_VERSION) {
      RECENT_GCC: diagnostic pop; break;
      MSVC: warning(pop); break;
  }
}