Support class objects as function return values

There is nothing special to do for return class objects from a function.
They can be handled the same as other objects such as dynamic arrays and
queues.

But there currently is an assert in the code that handles function calls
assigned to objects that will trigger if the target type is not an queue or
dynamic array.

This is because Icarus allows dynamic arrays to be initialized with a
single value and for that the element with of the dynamic array needs to be
known, so the single value expression can be evaluated correctly.

Since classes can not be initialized from vector expressions the width does
not matter in that case.

Update the code to only query the element width if the target type is an
dynamic array or queue and pass a placeholder value of 1 for the width
otherwise.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

elab_expr.cc

@@ -2783,10 +2783,14 @@ NetExpr* PECallFunction::elaborate_expr_(Design*des, NetScope*scope,
 NetExpr* PECallFunction::elaborate_expr(Design*des, NetScope*scope,
 					ivl_type_t type, unsigned flags) const
 {
-//cerr << "HERE: " << scope->basename() << ", " << *type << endl;
       const netdarray_t*darray = dynamic_cast<const netdarray_t*>(type);
-      assert(darray);
+      unsigned int width = 1;
-      return elaborate_expr(des, scope, darray->element_type()->packed_width(), flags);
+        // Icarus allows a dynamic array to be initialised with a single
+        // elementary value, in that case the expression needs to be evaluated
+        // with the rigth width.
+      if (darray)
+	    width = darray->element_type()->packed_width();
+      return elaborate_expr(des, scope, width, flags);
 }
 
 NetExpr* PECallFunction::elaborate_base_(Design*des, NetScope*scope, NetScope*dscope,