C macro for print struct's fields

demo.c

#include <stdio.h>
#include "printstruct.h"

typedef struct
{
  int a;
  char *b;
  char c;
  long int d;
  long long int e;
  unsigned long int f;
  unsigned long long int g;
  short int h;
  unsigned short i;
  float sprec;
  double dprec;
  long double tprec;
  void *ptr;
  struct
  {
    int a;
    int b;
  } sub;
} mytest;

int main(void)
{
  mytest test = {
      .a = 3,
      .b = "test",
      .c = 'x',
      .sprec = 3.141592f,
      .dprec = 81.0,
      .tprec = 625.0,
      .ptr = "any_value",
      .sub = {
          .a = 1,
          .b = 2,
      },
  };

  PRINT_STRUCT(0, test.sub, a, b);
  putchar('\n');
  PRINT_STRUCT(0, test, a, b, c, d, e, f, g, h, i, sprec, dprec, tprec, ptr);
  return 0;
}

printstruct.h

#ifndef _PRINTSTRUCT_H
#define _PRINTSTRUCT_H

#include <stdio.h>

#if __GNUC__ < 8
#define __VA_OPT__(...)
#error "printstruct needs __VA_OPT__ extension to be used. Please compile with GCC 8+."
#endif

#define PRINT_STRUCT(ident, _struct, ...)                    \
  printf("%*c%s {\n", ident + 1, *#_struct, (#_struct) + 1); \
  PRINT_STRUCT_1(ident, _struct, __VA_ARGS__);               \
  printf("%*c\n", ident + 1, '}')

#define PRINT_STRUCT_FIELD(ident, _struct, field)                                  \
  printf("  %*c%s", ident + 1, *#field, (#field) + 1);                             \
  printf(MASKTYPE(_struct.field), (int)(25 - sizeof(#field)), ":", _struct.field); \
  putchar('\n')

#define MASKTYPE(expr)                    \
  _Generic((expr),                        \
           char *                         \
           : "%*s \"%s\"",                \
             char                         \
           : "%*s '%c'",                  \
             int                          \
           : "%2$*1$s %3$d (0x%3$x)",     \
             unsigned int                 \
           : "%2$*1$s %3$u (0x%3$x)",     \
             short int                    \
           : "%2$*1$s %3$hd (0x%3$hx)",   \
             unsigned short int           \
           : "%2$*1$s %3$hd (0x%3$hx)",   \
             long int                     \
           : "%2$*1$s %3$ld (0x%3$lx)",   \
             unsigned long int            \
           : "%2$*1$s %3$ld (0x%3$lx)",   \
             long long int                \
           : "%2$*1$s %3$lld (0x%3$llx)", \
             unsigned long long int       \
           : "%2$*1$s %3$lld (0x%3$llx)", \
             float                        \
           : "%*s %f",                    \
             double                       \
           : "%*s %f",                    \
             long double                  \
           : "%*s %Lf",                   \
             default                      \
           : "%*s %p")

#define PRINT_STRUCT_1(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_2(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_2(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_3(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_3(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_4(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_4(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_5(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_5(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_6(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_6(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_7(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_7(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_8(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_8(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_9(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_9(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);       \
  __VA_OPT__(PRINT_STRUCT_10(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_10(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_11(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_11(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_12(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_12(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_13(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_13(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_14(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_14(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_15(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_15(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1);        \
  __VA_OPT__(PRINT_STRUCT_16(ident, _struct, __VA_ARGS__))

#define PRINT_STRUCT_16(ident, _struct, _1, ...) \
  PRINT_STRUCT_FIELD(ident, _struct, _1)

#endif /* _PRINTSTRUCT_H */