I suggest to remove this line from the list of the dmd compiler switches:

-w             warnings as errors (compilation will halt)


(I am not yet suggesting to remove that switch, I am just suggesting to remove it from the list of switches shown to the dmd user. The actual removal is for later).


(My preferred D compiler design is to have "warnings as messages" active on default and have a switch to disable them on request. Because lot of people don't read warnings. Giving "warnings as messages" on default is better.)