blockptr.c

#include <stdio.h>
#include <stdlib.h>
#include <Block.h>

typedef void (^vblock)(void);

vblock
f(void)
{
	__block int x = 42;
	__block int *y = &x;

	printf("x=%d, *y=%d, %s\n", x, *y, (y == &x ? "yeah!" : "arg!"));
	return Block_copy(^ {
		printf("x=%d, *y=%d, %s\n", x, *y, (y == &x ? "yeah!" : "arg!"));
	});
}

int
main(int argc, char **argv)
{
	vblock b = f();
	b();
	Block_release(b);
}

%  clang -fblocks blockptr.c -lBlocksRuntime
% ./a.out 
x=42, *y=42, yeah!
x=42, *y=21000256, arg!