[gnu.gcc] Using #ifdef __STDC__

Leisner.Henr@XEROX.COM (marty) (05/08/89)

I've noticed several (slightly brain-damaged) C compilers which define
__STDC__ to 0 internally (for no good reason except they thing it's a good
idea).

These compilers generally have a subset of the ANSI features.

So code which does
#ifdef __STDC__

will pass

and code which does
#ifdef __STDC__ == 1

will fail.

The ANSI May 1988 Dpans defines __STDC__ to the decimal constant 1.

So it seems it may be a good idea to do a #if instead of #ifdef
(I've recently came across code which broke on various C compilers due to
this glitch).

In the world of partial ANSI C compilers, it may be a good idea to use more
directives  (like USE_PROTOTYPES) to allow hand configuration for
incomplete ANSI implementations.

marty
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