deprecated using rdmd and dub build -dw

[Brother Bill]

 From page 375 of Programming in D.
```
import std.stdio;

void main() {
     do_something;
}

deprecated("Please use doSomething() instead.")     // No 
trailing semicolon, please
alias do_something = doSomething;

// void do_something() {
//     writeln("Using Eiffel snake_case, which doesn't pass D 
language style guide");
// }

void doSomething() {
     writeln("Using clean, mother approved camelCase styling which 
passes the D language style guide");
}
```

When running
```
dub build -dw
or
dub build -de
```

I get this error message, which makes no sense.
```
Error Error processing arguments: Can't parse string: bool should 
be case-insensitive 'true' or 'false'
              Run 'dub help' for usage information.
```

Kindly provide some sample code that properly handles deprecated.
I'm running on Windows DMD 2.111.0