var variable = self.n_expr.its_variable
if variable != null then
- #var orig = self.n_expr.mtype
+ var orig = self.n_expr.mtype
#var from = if orig != null then orig.to_s else "invalid"
#var to = if mtype != null then mtype.to_s else "invalid"
#debug("adapt {variable}: {from} -> {to}")
- self.after_flow_context.when_true.set_var(v, variable, mtype)
+
+ # Do not adapt if there is no information gain (i.e. adapt to a supertype)
+ if mtype == null or orig == null or not v.is_subtype(orig, mtype) then
+ self.after_flow_context.when_true.set_var(v, variable, mtype)
+ end
end
self.mtype = v.type_bool(self)