Conditional checking in defaults and add bodies

[pbroadbery]

Currently, the following code compiles. It shouldn't for the reasons indicated.

#include "foamlib"

ZZZ(A: with): Category == 
 with {
  if A has BasicType then
     foo: () -> ();
  default {
     if A has BasicType then {
        foo(): () == never
    }
  }
}
X: with == add;

QQQ(T: with): ZZZ X == add;

zzz(): () == {
   import from QQQ X;
   foo() -- this should be an error, as X is not a BasicType
}

zzz();

MMM(T: with): Category == with { if T has BasicType then { x: () -> () } }

--- PPP does not export 'x' in all cases where T has BasicType.  Thus it 
-- should fail
PPP(T: with): MMM T with == add { if T has Logic then { x(): () == never; }}

[pippijn]

@pbroadbery using "fix" with the ticket number anywhere in the commit text closes the ticket, even if it says "doesn't fix #ticket". So, I reopened it.