Find holes in C structs due to alignment

Question

Is there a way in gcc or clang (or any other compiler) to spit information about whether a struct has holes (memory alignment - wise) in it ?

Thank you.

ps: If

Answer 1

I Don't know any automatic tool, but this could be helpful example:

#include 

struct test {
  typea a;
  typeb b;
  typec c;
};

int gapB = offsetof(struct test, b) - (offsetof(struct test, a) + sizeof(typea));
int gapC = offsetof(struct test, c) - (offsetof(struct test, b) + sizeof(typeb));

printf("Gap of b:%d/n", gapB);
printf("Gap of c:%d/n", gapC);

*Note: you will have to do so for each two members in your stuck.