JS: Convert boolean to a newtype

Author: asgerf

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

@@ -1043,7 +1043,7 @@ module API {
         // property reads
         exists(DataFlow::SourceNode src, DataFlow::SourceNode pred, string propDesc |
           use(base, src) and
-          pred = trackUseNode(src, false, 0, propDesc) and
+          pred = trackUseNode(src, Promisification::notPromisified(), 0, propDesc) and
           propertyRead(pred, propDesc, lbl, ref) and
           // `module.exports` is special: it is a use of a def-node, not a use-node,
           // so we want to exclude it here
@@ -1253,6 +1253,26 @@ module API {
 
     private import semmle.javascript.dataflow.TypeTracking
 
+    private module Promisification {
+      private newtype TState =
+        /** Default statue; the tracked value has not been through any steps related to promisification. */
+        TNotPromisified() or
+        /** The tracked value is a function that has been through promisification. */
+        TPromisifiedFunction()
+
+      class State extends TState {
+        string toString() {
+          this = TNotPromisified() and result = "not-promisified"
+          or
+          this = TPromisifiedFunction() and result = "promisified-function"
+        }
+      }
+
+      State notPromisified() { result = TNotPromisified() }
+
+      State promisifiedFunction() { result = TPromisifiedFunction() }
+    }
+
     /**
      * Gets a data-flow node to which `nd`, which is a use of an API-graph node, flows.
      *
@@ -1267,19 +1287,20 @@ module API {
      *     and not necessarily the entire object.
      */
     private DataFlow::SourceNode trackUseNode(
-      DataFlow::SourceNode nd, boolean promisified, int boundArgs, string prop,
+      DataFlow::SourceNode nd, Promisification::State promisified, int boundArgs, string prop,
       DataFlow::TypeTracker t
     ) {
       t.start() and
       use(_, nd) and
       result = nd and
-      promisified = false and
+      promisified = Promisification::notPromisified() and
       boundArgs = 0 and
       prop = ""
       or
       exists(Promisify::PromisifyCall promisify |
-        trackUseNode(nd, false, boundArgs, prop, t.continue()).flowsTo(promisify.getArgument(0)) and
-        promisified = true and
+        trackUseNode(nd, Promisification::notPromisified(), boundArgs, prop, t.continue())
+            .flowsTo(promisify.getArgument(0)) and
+        promisified = Promisification::promisifiedFunction() and
         prop = "" and
         result = promisify
       )
@@ -1298,7 +1319,7 @@ module API {
       or
       exists(DataFlow::Node pred, string preprop |
         trackUseNode(nd, promisified, boundArgs, preprop, t.continue()).flowsTo(pred) and
-        promisified = false and
+        promisified = Promisification::notPromisified() and
         boundArgs = 0 and
         SharedTypeTrackingStep::loadStoreStep(pred, result, prop)
       |
@@ -1319,7 +1340,8 @@ module API {
      */
     pragma[noopt]
     private DataFlow::TypeTracker useStep(
-      DataFlow::Node nd, boolean promisified, int boundArgs, string prop, DataFlow::Node res
+      DataFlow::Node nd, Promisification::State promisified, int boundArgs, string prop,
+      DataFlow::Node res
     ) {
       exists(DataFlow::TypeTracker t, StepSummary summary, DataFlow::SourceNode prev |
         prev = trackUseNode(nd, promisified, boundArgs, prop, t) and
@@ -1331,7 +1353,7 @@ module API {
     }
 
     private DataFlow::SourceNode trackUseNode(
-      DataFlow::SourceNode nd, boolean promisified, int boundArgs, string prop
+      DataFlow::SourceNode nd, Promisification::State promisified, int boundArgs, string prop
     ) {
       result = trackUseNode(nd, promisified, boundArgs, prop, DataFlow::TypeTracker::end())
     }
@@ -1341,7 +1363,7 @@ module API {
      */
     cached
     DataFlow::SourceNode trackUseNode(DataFlow::SourceNode nd) {
-      result = trackUseNode(nd, false, 0, "")
+      result = trackUseNode(nd, Promisification::notPromisified(), 0, "")
     }
 
     private DataFlow::SourceNode trackDefNode(DataFlow::Node nd, DataFlow::TypeBackTracker t) {