__STDC__ defined as zero a problem

[mcdonald at uxe.cso.uiuc.edu]

I have noticed several programs posted to the net, or available
by ftp somewhere that contain lines like

#if __STDC__
  /* usually function prototypes */
#else
  /* old style declarations */
#endif

I find this a bit objectionable, in that this prevents getting the
benefits of new-style declarations using compilers that support them
but, correctly, declare __STDC__ to be zero or don't declare it at all.

It would be nice if they looked something like

#ifdef ANSI_prototypes
#undef ANSI_prototypes
#define ANSI_prototypes 1
#else
#define ANSI_prototypes 0
#endif

#if ((__STDC__) | (ANSI_prototypes))
  /* the rest as above....

Where ANSI_prototypes could be defined on the command line.

I admit that sort of stuff could lead to command-line pollution
by things like defining ANSI_trigraphs, ANSI_this, ANSI_that, etc.

On the other hand, though __STDC__ is supposed to be defined as 1 
for comforming compilers , and not redefinable, (is this correct,
standards gurus?) it might be possible in a not-really ANSI-C
compiler to make __STDC__ be defined as 0, and redefinable. The
standard surely shouldn't object to this, should it?

Your comments and flames are welcome.

Doug McDonald (mcdonald at uxe.cso.uiuc.edu)