SCOPE_EXIT macro in c

scope_exit.c

#ifndef __GNUC__
#error "nope"
#endif

#ifdef __clang__
#include <Block.h>
void __cleanblock(void (^*block)(void)) {
  (*block)();
  Block_release(*block);
}

#define SCOPE_EXIT                                                      \
  void (^__end_of_scope_func)(void)                                     \
  __attribute__((cleanup(__cleanblock))) = ^
#else
#define SCOPE_EXIT                                                      \
  auto void __end_of_scope_func(void *);                                \
  int __end_of_scope_var __attribute__((cleanup(__end_of_scope_func))); \
  void __end_of_scope_func(void *x __attribute__((unused)))
#endif

#include <stdio.h>
int main() {
  SCOPE_EXIT {
    puts("end of main");
  };
  puts("main scope");
  {
    SCOPE_EXIT {
      puts("end of scope 1");
    };
    puts("scope1");
  }
  puts("still main scope");
  {
    SCOPE_EXIT {
      puts("end of scope 2");
    };
    puts("scope2");
  }
  puts("main scope again");
}