chain(const(array of class)) fails

[Marc Schütz via Digitalmars-d-learn]

The constraint that fails is the one with `CommonType`:

     pragma(msg, CommonType!(const(B), const(C))); // void

`CommonType` uses the `?:` operator to derive the common type:

     writeln(true ? b : c);
     // Error: incompatible types for ((b) : (c)): 'const(B[])' 
and 'const(C[])'
     writeln(true ? b[0] : c[0]);
     // Error: incompatible types for ((b[0]) : (c[0])): 
'const(B)' and 'const(C)'

At the moment I can't see a reason why that shouldn't work.