gcc strcpy pseudo bug or detail

["Mauricio Labra" <mauricio dot labra at construmart dot cl>]

Hi, sorry for my english...

I have a RH 7.2 and detect this detail (in C example):

# rpm -qi gcc
Name        : gcc                          Relocations: (not relocateable)
Version     : 2.96                              Vendor: Red Hat, Inc.
Release     : 98                            Build Date: mar 04 sep 2001 14:10:42 CLT
Install date: mar 09 jul 2002 07:53:37 CLT      Build Host: stripples.devel.redhat.com
Group       : Development/Languages         Source RPM: gcc-2.96-98.src.rpm
Size        : 8376529                          License: GPL
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
URL         : http://gcc.gnu.org
Summary     : Various compilers (C, C++, Objective-C, Java, ...)
Description :
The gcc package contains the GNU Compiler Collection: cc and gcc. You'll need
this package in order to compile C/C++ code.


Source sample program x.c :

#include <stdio.h>
#include <string.h>

int main()
{
        char tmp[80];

        strcpy(tmp,msg());
        puts(tmp);
        return(0);
}

char *msg()
{
        return("Mensaje de prueba");
}

This sample have a warnings...

# gcc -O3 -Wall x.c
x.c: In function `main':
x.c:9: warning: implicit declaration of function `msg'
x.c:9: warning: passing arg 1 of `strlen' makes pointer from integer without a cast
x.c:9: warning: passing arg 1 of `strlen' makes pointer from integer without a cast
x.c:9: warning: passing arg 1 of `strlen' makes pointer from integer without a cast
x.c:9: warning: passing arg 2 of `memcpy' makes pointer from integer without a cast
x.c:9: warning: passing arg 2 of `strcpy' makes pointer from integer without a cast
x.c: At top level:
x.c:15: warning: type mismatch with previous implicit declaration
x.c:9: warning: previous implicit declaration of `msg'
x.c:15: warning: `msg' was previously implicitly declared to return `int'


Whats are the warnings "makes pointer from integer without a cast" of strlen or memcpy functions?
I don't use this functions !

#gcc -O3 -Wall -E x.c
...
...
...
int main()
{
        char tmp[80];

        (__extension__ (__builtin_constant_p (msg()) ? (((size_t)(const void *)((msg()) + 1) - (size_t)(const
 void *)(msg()) == 1) && strlen (msg()) + 1 <= 8 ? __strcpy_small (tmp, __extension__ (((__const unsigned cha
r *) (__const char *) (msg()))[0 + 1] << 8 | ((__const unsigned char *) (__const char *) (msg()))[0]), __exte
nsion__ (((__const unsigned char *) (__const char *) (msg()))[4 + 1] << 8 | ((__const unsigned char *) (__con
st char *) (msg()))[4]), __extension__ (((((__const unsigned char *) (__const char *) (msg()))[0 + 3] << 8 |
((__const unsigned char *) (__const char *) (msg()))[0 + 2]) << 8 | ((__const unsigned char *) (__const char
*) (msg()))[0 + 1]) << 8 | ((__const unsigned char *) (__const char *) (msg()))[0]), __extension__ (((((__con
st unsigned char *) (__const char *) (msg()))[4 + 3] << 8 | ((__const unsigned char *) (__const char *) (msg(
)))[4 + 2]) << 8 | ((__const unsigned char *) (__const char *) (msg()))[4 + 1]) << 8 | ((__const unsigned cha
r *) (__const char *) (msg()))[4]), strlen (msg()) + 1) : (char *) memcpy (tmp, msg(), strlen (msg()) + 1)) :
 strcpy (tmp, msg())));
        puts(tmp);
        return(0);
}

char *msg()
{
        return("Mensaje de prueba");
}

Aha!!   Why gcc transform a simple strcpy in this macro code ?
The strcpy with function argument are dangerous...!!!
this execute many times the function !!!

Solution :

#include <stdio.h>
#include <string.h>

char *msg()
{
        return("Mensaje de prueba");
}

int main()
{
        char tmp[80];
        char *aux;

        aux=msg();
        strcpy(tmp,aux);
//      Esto es mas simple
//      memcpy(tmp,msg(),strlen(msg())+1);
        puts(tmp);
        return(0);
}

#gcc -O3 -Wall x.c
No warnings.

#gcc -O3 -Wall -E x.c
...
...
char *msg()
{
        return("Mensaje de prueba");
}

int main()
{
        char tmp[80];
        char *aux;

        aux=msg();
        (__extension__ (__builtin_constant_p (aux) ? (((size_t)(const void *)((aux) + 1) - (size_t)(const void *)(aux) == 1) && strlen (aux) + 1 <= 8 ? __strcpy_small (tmp, __extension__ (((__const unsigned char *) (__const char *) (aux))[0 + 1] << 8 | ((__const unsigned char *) (__const char *) (aux))[0]), __extension__ (((__const unsigned char *) (__const char *) (aux))[4 + 1] << 8 | ((__const unsigned char *) (__const char *) (aux))[4]), __extension__ (((((__const unsigned char *) (__const char *) (aux))[0 + 3] << 8 | ((__const unsigned char *) (__const char *) (aux))[0 + 2]) << 8 | ((__const unsigned char *) (__const char *) (aux))[0 + 1]) << 8 | ((__const unsigned char *) (__const char *) (aux))[0]), __extension__ (((((__const unsigned char *) (__const char *) (aux))[4 + 3] << 8 | ((__const unsigned char *) (__const char *) (aux))[4 + 2]) << 8 | ((__const unsigned char *) (__const char *) (aux))[4 + 1]) << 8 | ((__const unsigned char *) (__const char *) (aux))[4]), strlen (aux) + 1) : (char *) memcpy (tmp, aux, strlen (aux) + 1)) : strcpy (tmp, aux)));
        puts(tmp);
        return(0);
}


Please, tell me what is this and/or how to skip this macro...
and what other functions use this kind of macro control ?
I use string functions very well, and don't need extra code.

Thanxz.