Merge ConditionBlock and BarrierGuard

Author: hmac

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

@@ -160,31 +160,26 @@ class Content extends TContent {
 }
 
 /**
- * A node that controls whether other nodes are evaluated.
+ * A guard that validates some expression.
+ *
+ * To use this in a configuration, extend the class and provide a
+ * characteristic predicate precisely specifying the guard, and override
+ * `checks` to specify what is being validated and in which branch.
+ *
+ * It is important that all extending classes in scope are disjoint.
  */
-class GuardNode extends CfgNodes::ExprCfgNode {
-  ConditionBlock conditionBlock;
+abstract class BarrierGuard extends CfgNodes::ExprCfgNode {
+  private ConditionBlock conditionBlock;
 
-  GuardNode() { this = conditionBlock.getLastNode() }
+  BarrierGuard() { this = conditionBlock.getLastNode() }
 
   /** Holds if this guard controls block `b` upon evaluating to `branch`. */
-  predicate controlsBlock(BasicBlock bb, boolean branch) {
+  private predicate controlsBlock(BasicBlock bb, boolean branch) {
     exists(SuccessorTypes::BooleanSuccessor s | s.getValue() = branch |
       conditionBlock.controls(bb, s)
     )
   }
-}
 
-/**
- * A guard that validates some expression.
- *
- * To use this in a configuration, extend the class and provide a
- * characteristic predicate precisely specifying the guard, and override
- * `checks` to specify what is being validated and in which branch.
- *
- * It is important that all extending classes in scope are disjoint.
- */
-abstract class BarrierGuard extends GuardNode {
   /**
    * Holds if this guard validates `expr` upon evaluating to `branch`.
    * For example, the following code validates `foo` when the condition

ql/test/library-tests/dataflow/barrier-guards/barrier-guards.rb

@@ -26,6 +26,8 @@
 
 unless foo != "foo"
     foo
+else
+    foo
 end
 
 foo