headers and reserved symbols

[Karl Heuer]

From: karl at IMA.IMA.ISC.COM (Karl Heuer)

In ANSI C, several symbols are reserved only when their associated header is
included.  For example, if a program does not use <stdlib.h>, then it could
use the symbol EXIT_SUCCESS as a local variable and still be strictly
conforming.  (Hence, the implementation must not have one header include
another.)

Is this also true of POSIX?  I thought 1003.1 used pretty much the same
namespace rules as X3J11, but I can't find an explicit guarantee in the Green
Book.  In particular, given that <sys/types.h> reserves the entire *_t
namespace, is it safe for an application to create such a typedef in a module
that does not require that header?

Karl W. Z. Heuer (karl at haddock.isc.com or ima!haddock!karl), The Walking Lint

Volume-Number: Volume 18, Number 33