CPP: Fix AV Rule 95 performance issue.

Author: geoffw0

cpp/ql/src/jsf/4.10 Classes/AV Rule 95.ql

@@ -11,16 +11,19 @@
  */
 import cpp
 
-from Parameter p, Parameter superP, MemberFunction subF, MemberFunction superF, int i, string subValue, string superValue
-where p.hasInitializer()
-  and subF.getParameter(i) = p
-   and superP.hasInitializer()
+predicate parameterWithDefault(MemberFunction f, int ix, Parameter p, Expr initExpr, string initValue) {
+  f.getParameter(ix) = p and
+  p.hasInitializer() and
+  initExpr = p.getInitializer().getExpr() and
+  initValue = initExpr.getValue()
+}
+
+from Parameter p, Parameter superP, MemberFunction subF, MemberFunction superF, int i, Expr subExpr, string subValue, string superValue
+where parameterWithDefault(subF, i, p, subExpr, subValue)
    and subF.overrides(superF)
-   and superF.getParameter(i) = superP
-   and subValue = p.getInitializer().getExpr().getValue()
-   and superValue = superP.getInitializer().getExpr().getValue()
+   and parameterWithDefault(superF, i, superP, _, superValue)
    and subValue != superValue
-select p.getInitializer().getExpr(),
+select subExpr,
    "Parameter " + p.getName() +
    " redefines its default value to " + subValue +
    " from the inherited default value " + superValue +