revert the Taint stage, as it caused an alert for ql/abstract-class-import

Author: erik-krogh

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

@@ -3,7 +3,6 @@ private import semmle.python.dataflow.new.DataFlow
 private import semmle.python.dataflow.new.internal.DataFlowPrivate as DataFlowPrivate
 private import semmle.python.dataflow.new.internal.TaintTrackingPublic
 private import semmle.python.ApiGraphs
-private import semmle.python.internal.CachedStages
 
 /**
  * Holds if `node` should be a sanitizer in all global taint flow configurations
@@ -31,7 +30,6 @@ private module Cached {
    */
   cached
   predicate defaultAdditionalTaintStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
-    Stages::Taint::ref() and
     localAdditionalTaintStep(nodeFrom, nodeTo)
     or
     any(AdditionalTaintStep a).step(nodeFrom, nodeTo)
@@ -44,7 +42,6 @@ private module Cached {
    */
   cached
   predicate localAdditionalTaintStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
-    Stages::Taint::ref() and
     concatStep(nodeFrom, nodeTo)
     or
     subscriptStep(nodeFrom, nodeTo)

python/ql/lib/semmle/python/internal/CachedStages.qll

@@ -176,32 +176,4 @@ module Stages {
       PointsTo::AttributePointsTo::variableAttributePointsTo(_, _, _, _, _)
     }
   }
-
-  /**
-   * The `taint` stage.
-   */
-  cached
-  module Taint {
-    /**
-     * Always holds.
-     * Ensures that a predicate is evaluated as part of the DataFlow stage.
-     */
-    cached
-    predicate ref() { 1 = 1 }
-
-    private import semmle.python.dataflow.new.internal.TaintTrackingPrivate as TaintTrackingPrivate
-
-    /**
-     * DONT USE!
-     * Contains references to each predicate that use the above `ref` predicate.
-     */
-    cached
-    predicate backref() {
-      1 = 1
-      or
-      TaintTrackingPrivate::localAdditionalTaintStep(_, _)
-      or
-      TaintTrackingPrivate::defaultAdditionalTaintStep(_, _)
-    }
-  }
 }