Implicit fall through not detected (Example from lex.html)

[Andre via Digitalmars-d-learn]

Hi,

I am little bit confused. I am copied the switch example from 
lex.html
and expected that case 6 will lead to a syntax error due to the 
missing
break statement. But the example compiles without error (C:>dmd 
app)

I tried 3 different dmd version, also the newest beta.

Kind regards
André

import std.stdio: writeln;

void main()
{

int number;
string message;

switch (number)
{
  default:    // valid
        throw new Exception("unknown number");

  case 3:     // valid
        message ~= "three ";
        break;

  case 5:     // valid
        message ~= "five ";
        goto case;

  case 6:     // ERROR: implicit fall-through
        message ~= "six ";

  case 1:     // valid
  case 2:     // valid
        message = "one or two";
}

}