scc

 1#include <string.h>
 2
 3#undef strcat
 4
 5char *
 6strcat(char *restrict s1, const char *restrict s2)
 7{
 8	char *ret;
 9
10	for (ret = s1; *s1; ++s1)
11		;
12	while ((*s1++ = *s2++) != 0)
13		;
14
15	return ret;
16}