dtolnay

  A=0.1000000000000000055511151231257827021181583404541015625
  B=0.100000000000000012490009027033011079765856266021728515625
  C=0.10000000000000001942890293094023945741355419158935546875

  0.1000000000000000124900090270330110797658562660217285156249
  0.1000000000000000124900090270330110797658562660217285156251

  1  if (argc <= 2)
  2    puts("A");
  3  puts("B");
  4  if (argc <= 2)
  5    unreachable();
  6  else
  7    return puts("C");
  8  return puts("D");

    compile_error!("You meant to …");