+ # Generate type checks in the C code to check covariant parameters
+ fun parameter_check(node: ANode, mpropdef: MMethodDef, args: Array[Instance])
+ do
+ var msignature = mpropdef.msignature
+ for i in [0..msignature.arity[ do
+ # skip test for vararg since the array is instantiated with the correct polymorphic type
+ if msignature.vararg_rank == i then continue
+
+ # skip if the cast is not required
+ var origmtype = mpropdef.mproperty.intro.msignature.mparameters[i].mtype
+ if not origmtype.need_anchor then continue
+
+ # get the parameter type
+ var mtype = msignature.mparameters[i].mtype
+ var anchor = args.first.mtype.as(MClassType)
+ mtype = mtype.anchor_to(self.mainmodule, anchor)
+ if not args[i+1].mtype.is_subtype(self.mainmodule, anchor, mtype) then
+ node.fatal(self, "Cast failed")
+ end
+ end
+ end
+