Ruby: make PostUpdateNode public

Author: nickrolfe

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

@@ -820,24 +820,15 @@ string ppReprType(DataFlowType t) { result = t.toString() }
 pragma[inline]
 predicate compatibleTypes(DataFlowType t1, DataFlowType t2) { any() }
 
-/**
- * A node associated with an object after an operation that might have
- * changed its state.
- *
- * This can be either the argument to a callable after the callable returns
- * (which might have mutated the argument), or the qualifier of a field after
- * an update to the field.
- *
- * Nodes corresponding to AST elements, for example `ExprNode`, usually refer
- * to the value before the update.
- */
-abstract class PostUpdateNode extends Node {
-  /** Gets the node before the state update. */
-  abstract Node getPreUpdateNode();
+module PostUpdateNode {
+  abstract class Range extends Node {
+    /** Gets the node before the state update. */
+    abstract Node getPreUpdateNode();
+  }
 }
 
 private module PostUpdateNodes {
-  class ExprPostUpdateNode extends PostUpdateNode, NodeImpl, TExprPostUpdateNode {
+  class ExprPostUpdateNode extends PostUpdateNode::Range, NodeImpl, TExprPostUpdateNode {
     private CfgNodes::ExprCfgNode e;
 
     ExprPostUpdateNode() { this = TExprPostUpdateNode(e) }
@@ -851,7 +842,7 @@ private module PostUpdateNodes {
     override string toStringImpl() { result = "[post] " + e.toString() }
   }
 
-  private class SummaryPostUpdateNode extends SummaryNode, PostUpdateNode {
+  private class SummaryPostUpdateNode extends SummaryNode, PostUpdateNode::Range {
     private Node pre;
 
     SummaryPostUpdateNode() { FlowSummaryImpl::Private::summaryPostUpdateNode(this, pre) }

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPublic.qll

@@ -121,6 +121,22 @@ class LocalSourceNode extends Node {
   LocalSourceNode backtrack(TypeBackTracker t2, TypeBackTracker t) { t2 = t.step(result, this) }
 }
 
+/**
+ * A node associated with an object after an operation that might have
+ * changed its state.
+ *
+ * This can be either the argument to a callable after the callable returns
+ * (which might have mutated the argument), or the qualifier of a field after
+ * an update to the field.
+ *
+ * Nodes corresponding to AST elements, for example `ExprNode`, usually refer
+ * to the value before the update.
+ */
+class PostUpdateNode extends Node instanceof PostUpdateNode::Range {
+  /** Gets the node before the state update. */
+  Node getPreUpdateNode() { result = super.getPreUpdateNode() }
+}
+
 cached
 private predicate hasLocalSource(Node sink, Node source) {
   // Declaring `source` to be a `SourceNode` currently causes a redundant check in the

ruby/ql/lib/codeql/ruby/typetracking/TypeTrackerSpecific.qll

@@ -147,7 +147,7 @@ predicate basicStoreStep(Node nodeFrom, Node nodeTo, string content) {
   // TODO: support SetterMethodCall inside TuplePattern
   exists(ExprNodes::MethodCallCfgNode call |
     content = getSetterCallAttributeName(call.getExpr()) and
-    nodeTo.(DataFlowPrivate::PostUpdateNode).getPreUpdateNode().asExpr() = call.getReceiver() and
+    nodeTo.(DataFlowPublic::PostUpdateNode).getPreUpdateNode().asExpr() = call.getReceiver() and
     call.getExpr() instanceof AST::SetterMethodCall and
     call.getArgument(call.getNumberOfArguments() - 1) =
       nodeFrom.(DataFlowPublic::ExprNode).getExprNode()