solutions may have not yet been computed in annotation

stcheck.py

@@ -367,9 +367,10 @@
                             continue
             # shared references
             newvar.stinfo['constnode'] = var.stinfo['constnode']
-            newvar.stinfo['possibletypes'] = var.stinfo['possibletypes']
-            for sol in newvar.stmt.solutions:
-                sol[newvar.name] = sol[var.name]
+            if newvar.stmt.solutions: # solutions already computed
+                newvar.stinfo['possibletypes'] = var.stinfo['possibletypes']
+                for sol in newvar.stmt.solutions:
+                    sol[newvar.name] = sol[var.name]
             rel = exists.add_relation(var, 'identity', newvar)
             # we have to force visit of the introduced relation
             self.visit_relation(rel, exists)