C++: Add false positive.

Author: MathiasVP

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BadAdditionOverflowCheck/PointlessSelfComparison.expected

@@ -1,4 +1,5 @@
 | templates.cpp:17:5:17:25 | ... < ... | Self comparison. |
+| templates.cpp:31:20:31:41 | ... <= ... | Self comparison. |
 | test.cpp:13:11:13:21 | ... == ... | Self comparison. |
 | test.cpp:79:11:79:32 | ... == ... | Self comparison. |
 | test.cpp:83:10:83:15 | ... == ... | Self comparison. |

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BadAdditionOverflowCheck/templates.cpp

@@ -20,3 +20,22 @@ bool compareValues() {
 bool callCompareValues() {
   return compareValues<C1, C2> || compareValues<C1, C1>();
 }
+
+template <bool C, typename T = void>
+struct enable_if {};
+
+template <typename T>
+struct enable_if<true, T> { typedef T type; };
+
+template<typename T1, typename T2>
+typename enable_if<T1::value <= T2::value, bool>::type constant_comparison() {
+  return true;
+}
+
+struct Value0 {
+  const static int value = 0;
+};
+
+void instantiation_with_pointless_comparison() {
+  constant_comparison<Value0, Value0>();
+}