Wshadow check

beyond@rules->$ cat global.c
#include<stdio.h>
#include<stdlib.h>

int x=5;

void foo(int x,int y)
{
	x=y;
	printf("%d %d\n",x,y);
}

int main()
{
	foo(2,3);
	return 0;
}
beyond@rules->$ gcc -Wall -W global.c -o global
beyond@rules->$ rm global
beyond@rules->$ gcc -Wshadow -Wall -W global.c -o global
global.c: In function ‘foo’:
global.c:6:14: warning: declaration of ‘x’ shadows a global declaration [-Wshadow]
global.c:4:5: warning: shadowed declaration is here [-Wshadow]
beyond@rules->$ ^C
beyond@rules->$