emulating indirect weak aliases with strong direct aliases for Mach-O

alias.c

#include <stdio.h>

#if HAVE_ALIASES

#define weak_alias(old, new) \
        extern __typeof(old) new __attribute__((weak, alias(#old)))

#else

#define weak_alias(old, new) \
        __asm__(".globl _" #new); \
        __asm__("_" #new " = _" #old); \
        extern __typeof(old) new __attribute__((weak_import))

#endif

void __foo()
{
        printf("foo\n");
}

weak_alias(__foo, foo);

int main()
{
        foo();
}