Code shared from run.dlang.io. Run with '-preview=bitfields'

main.d

import std;

alias bit = bool;
struct integer
{
      bit 
        sign: 1, 
        bit1: 1,
        bit2: 1,
        bit3: 1,
        bit4: 1,
        bit5: 1,
        bit6: 1,
        bit7: 1
      ;
}

void main()
{
    writeln("Structure size: ", integer.sizeof, " byte.");
    
    integer data = {0,1,1,0,0,1,0,0};
    writeln(data);
    
    writeln("Signed integer: ", data.sign);
    writeln("First bit is set: ", data.bit1);
}