Debug predicates for missing def/use nodes

Author: asgerf

javascript/ql/lib/semmle/javascript/ApiGraphs.qll

@@ -795,7 +795,7 @@ module API {
        * Holds if `rhs` is the right-hand side of a definition of a node that should have an
        * incoming edge from `base` labeled `lbl` in the API graph.
        */
-      private predicate rhs(TApiNode base, Label::ApiLabel lbl, DataFlow::Node rhs) {
+      predicate rhs(TApiNode base, Label::ApiLabel lbl, DataFlow::Node rhs) {
         hasSemantics(rhs) and
         (
           base = MkRoot() and
@@ -1031,7 +1031,7 @@ module API {
        * Holds if `ref` is a use of a node that should have an incoming edge from `base` labeled
        * `lbl` in the API graph.
        */
-      private predicate use(TApiNode base, Label::ApiLabel lbl, DataFlow::Node ref) {
+      predicate use(TApiNode base, Label::ApiLabel lbl, DataFlow::Node ref) {
         hasSemantics(ref) and
         (
           base = MkRoot() and
@@ -1638,6 +1638,16 @@ module API {
     import Cached
 
     private module Debug {
+      query predicate missingDefNode(DataFlow::Node node) {
+        Stage1::rhs(_, _, node) and
+        not exists(MkDef(node))
+      }
+
+      query predicate missingUseNode(DataFlow::Node node) {
+        Stage1::use(_, _, node) and
+        not exists(MkUse(node))
+      }
+
       query predicate lostEdge(Node pred, Label::ApiLabel lbl, Node succ) {
         Stage1::edge(pred, lbl, succ) and
         not Cached::edge(pred, lbl, succ)