Bitfield width specifiers

bitfield.cxx

#include <cstdio>

int read_value(const char* prompt) {
  puts(prompt);
  int x = 0;
  scanf("%d", &x);
  return x;
}

struct S {
  constexpr S(int value) : value_(value) { }

  constexpr operator int() const {
    return value_;
  }

  int value_;
};

template<typename type_t>
struct X {
  int value1 : S { 13 } { 17 };
  int value2 : (@meta read_value("enter bitfield size:")) { 18 };
};

int main() { 
  X<double> x { };
  printf("value1 = %d value2 = %d\n", x.value1, x.value2);
  return 0;
}

terminal

$ circle bitfield.cxx
enter bitfield size:
11
$ ./bitfield 
value1 = 17 value2 = 18