python: Do not remove ChainedConfigs12.qll

since it was clearly already used.
Add deprecation message instead.

Author: yoff

python/ql/lib/semmle/python/security/dataflow/ChainedConfigs12.qll

@@ -0,0 +1,85 @@
+/**
+ * DEPRECATED -- use flow state instead
+ *
+ * This defines a `PathGraph` where sinks from `TaintTracking::Configuration`s are identified with
+ * sources from `TaintTracking2::Configuration`s if they represent the same `ControlFlowNode`.
+ *
+ * Paths are then connected appropriately.
+ */
+
+import python
+import semmle.python.dataflow.new.DataFlow
+import semmle.python.dataflow.new.DataFlow2
+import semmle.python.dataflow.new.TaintTracking
+import semmle.python.dataflow.new.TaintTracking2
+
+/**
+ * A `DataFlow::Node` that appears as a sink in Config1 and a source in Config2.
+ */
+private predicate crossoverNode(DataFlow::Node n) {
+  any(TaintTracking::Configuration t1).isSink(n) and
+  any(TaintTracking2::Configuration t2).isSource(n)
+}
+
+/**
+ * A new type which represents the union of the two sets of nodes.
+ */
+private newtype TCustomPathNode =
+  Config1Node(DataFlow::PathNode node1) { not crossoverNode(node1.getNode()) } or
+  Config2Node(DataFlow2::PathNode node2) { not crossoverNode(node2.getNode()) } or
+  CrossoverNode(DataFlow::Node node) { crossoverNode(node) }
+
+/**
+ * A class representing the set of all the path nodes in either config.
+ */
+class CustomPathNode extends TCustomPathNode {
+  /** Gets the PathNode if it is in Config1. */
+  DataFlow::PathNode asNode1() {
+    this = Config1Node(result) or this = CrossoverNode(result.getNode())
+  }
+
+  /** Gets the PathNode if it is in Config2. */
+  DataFlow2::PathNode asNode2() {
+    this = Config2Node(result) or this = CrossoverNode(result.getNode())
+  }
+
+  /**
+   * Holds if this element is at the specified location.
+   * The location spans column `startcolumn` of line `startline` to
+   * column `endcolumn` of line `endline` in file `filepath`.
+   * For more information, see
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
+   */
+  predicate hasLocationInfo(
+    string filepath, int startline, int startcolumn, int endline, int endcolumn
+  ) {
+    asNode1().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
+    or
+    asNode2().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
+  }
+
+  /** Gets a textual representation of this element. */
+  string toString() {
+    result = asNode1().toString()
+    or
+    result = asNode2().toString()
+  }
+}
+
+/** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
+query predicate edges(CustomPathNode a, CustomPathNode b) {
+  // Edge is in Config1 graph
+  DataFlow::PathGraph::edges(a.asNode1(), b.asNode1())
+  or
+  // Edge is in Config2 graph
+  DataFlow2::PathGraph::edges(a.asNode2(), b.asNode2())
+}
+
+/** Holds if `n` is a node in the graph of data flow path explanations. */
+query predicate nodes(CustomPathNode n, string key, string val) {
+  // Node is in Config1 graph
+  DataFlow::PathGraph::nodes(n.asNode1(), key, val)
+  or
+  // Node is in Config2 graph
+  DataFlow2::PathGraph::nodes(n.asNode2(), key, val)
+}