Python: add debug predicates for unmapped steps

Author: yoff

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -520,6 +520,13 @@ module VariableCapture {
       Flow::storeStep(closureNodeFrom, v, closureNodeTo)
     }
 
+    predicate unmappedFlowStoreStep(
+      Flow::ClosureNode closureNodeFrom, CapturedVariable v, Flow::ClosureNode closureNodeTo
+    ) {
+      Flow::storeStep(closureNodeFrom, v, closureNodeTo) and
+      not flowStoreStep(_, closureNodeFrom, v, closureNodeTo, _)
+    }
+
     predicate flowReadStep(
       Node nodeFrom, Flow::ClosureNode closureNodeFrom, CapturedVariable v,
       Flow::ClosureNode closureNodeTo, Node nodeTo
@@ -529,13 +536,26 @@ module VariableCapture {
       Flow::readStep(closureNodeFrom, v, closureNodeTo)
     }
 
+    predicate unmappedFlowReadStep(
+      Flow::ClosureNode closureNodeFrom, CapturedVariable v, Flow::ClosureNode closureNodeTo
+    ) {
+      Flow::readStep(closureNodeFrom, v, closureNodeTo) and
+      not flowReadStep(_, closureNodeFrom, v, closureNodeTo, _)
+    }
+
     predicate flowValueStep(
       Node nodeFrom, Flow::ClosureNode closureNodeFrom, Flow::ClosureNode closureNodeTo, Node nodeTo
     ) {
       closureNodeFrom = asClosureNode(nodeFrom) and
       closureNodeTo = asClosureNode(nodeTo) and
       Flow::localFlowStep(closureNodeFrom, closureNodeTo)
     }
+
+    predicate unmappedFlowValueStep(
+      Flow::ClosureNode closureNodeFrom, Flow::ClosureNode closureNodeTo
+    ) {
+      Flow::localFlowStep(closureNodeFrom, closureNodeTo) and
+      not flowValueStep(_, closureNodeFrom, closureNodeTo, _)
   }
 }