Re: linux/macros.h(new) and linux/list.h(mod) ...

[Arnaldo Carvalho de Melo]

Em Fri, Jul 06, 2001 at 12:08:55AM +0100, David Woodhouse escreveu:
> 
> #define min(a,b) __magic_minfoo(a,b, __var##__LINE__, __var2##__LINE__)
> 
> #define __magic_minfoo(A,B,C,D) \
> 	({ typeof(A) C = (A); typeof(B) D = (B); C>D?D:C; })
> 
> void main(void)
> {
> 	int __var11=5, __var211=7;
> 
> 	printf("min(%d,%d) = %d (should be 11: %d)\n", __var11, __var211, min(__var11, __var211), __LINE__);
> }

Have you looked at the preprocessor output?

[acme@brinquedo /tmp]$ gcc -E a.c -o -   # or 'cpp < a.c'
# 1 "a.c"
void main(void)
{
        int __var11=5, __var211=7;

        printf("min(%d,%d) = %d (should be 11: %d)\n", __var11, __var211,
+ ({ typeof(  __var11  )   __var__LINE__  = (  __var11  ); typeof(
__var211  )   __var2__LINE__  = (   __var211  );   __var__LINE__ >
__var2__LINE__ ?  __var2__LINE__ :  __var__LINE__ ; })  , 11);
}

I didn't found a way to generate unique variable names using __LINE__

- Arnaldo