Ruby: Add regex consistency queries

Author: hvitved

ruby/ql/consistency-queries/RegExpConsistency.ql

@@ -0,0 +1,8 @@
+import codeql.ruby.security.performance.RegExpTreeView
+
+query predicate nonUniqueChild(RegExpParent parent, int i, RegExpTerm child) {
+  child = parent.getChild(i) and
+  strictcount(parent.getChild(i)) > 1
+}
+
+query predicate cyclic(RegExpParent parent) { parent = parent.getAChild+() }

ruby/ql/lib/codeql/ruby/security/performance/RegExpTreeView.qll

@@ -69,7 +69,7 @@ class RegExpParent extends TRegExpParent {
 
   RegExpTerm getChild(int i) { none() }
 
-  RegExpTerm getAChild() { result = this.getChild(_) }
+  final RegExpTerm getAChild() { result = this.getChild(_) }
 
   int getNumChild() { result = count(this.getAChild()) }