RE: Gcc 3.0, printf() and exim-3.30

["bmj2001" <bmj2001 at bellsouth dot net>]

Changes. The standards committee had its reasons.

-----Original Message-----
From: gcc-owner@gcc.gnu.org [mailto:gcc-owner@gcc.gnu.org]On Behalf Of
Russ Allbery
Sent: Thursday, June 21, 2001 3:42 AM
To: Nix
Cc: Vadim Vygonets; gcc@gcc.gnu.org
Subject: Re: Gcc 3.0, printf() and exim-3.30


Nix <nix@esperi.demon.co.uk> writes:

> Nope; printf is not a macro, and GCC does not define printf :)

You're correct that GCC does not define printf, of course, but in recent
versions of glibc, printf is indeed a macro.

/usr/include/stdio.h:

/* If we are compiling with optimizing read this file.  It contains
   several optimizing inline functions and macros.  */
#ifdef __USE_EXTERN_INLINES
# include <bits/stdio.h>
#endif

/usr/include/bits/stdio.h:

#ifdef __USE_EXTERN_INLINES
/* Since version 2.97 GCC knows about `fprintf' and can optimize certain
   cases.  Help gcc to optimize more code by mapping `printf' to the known
   `fprintf' function.  Unfortunately we have to use a macro.  */
# if __GNUC_PREREQ (2,97)
#  define printf(fmt, args...) fprintf (stdout, fmt, ##args)
# endif

You didn't see this before because glibc doesn't enable this optimization
unless the version of gcc is greater than 2.96.

firebird1:/root# rpm -q glibc
glibc-2.2-12

(Out of curiosity, is that little aid to GCC as braindead as it looks?
I'd think that if GCC optimized fprintf, it would pick up printf too....)

-- 
Russ Allbery (rra@stanford.edu)             <http://www.eyrie.org/~eagle/>