Question

I need help with a compile error that I am getting.

The error is:
error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]

on the following line

PRINT_INDENT("Inode2 PTR: %p\n", (void *)ptr);

Context

unsigned int ptr;
memcpy(&ptr, value, sizeof(ptr));
PRINT_INDENT("Inode2 PTR: %p\n", (void *)ptr);

#define PRINT_INDENT(...) ({int __j = indent_level; while (__j-- > 0) printf("  "); printf(__VA_ARGS__);})

Answer 1

Are you using a 64-bit platform with 32-bit ints? If so, the error is self-explanatory. ptr is a 32-bit variable, and you’re casting it to a 64-bit void *. A workaround is to first cast it to an unsigned long long and then cast the result to a void *.

PRINT_INDENT("Inode2 PTR: %p\n", (void *)(unsigned long long)ptr);

But why are you doing this? Why not just print ptr as an unsigned int instead of casting it to a void * as follows:

PRINT_INDENT("Inode2 PTR: %u\n", ptr);