Fix subtle typing issue with std::makr_pair

Dave Bartolomeo · Dave Bartolomeo · commit 7da4eef90d58 · 2020-10-17T08:53:20.000-04:00
diff --git a/cpp/ql/test/library-tests/dataflow/taint-tests/stl.h b/cpp/ql/test/library-tests/dataflow/taint-tests/stl.h
@@ -1,28 +1,28 @@
 
 typedef unsigned long size_t;
 
-template<class T>
-struct remove_const { typedef T type; };
 
-template<class T>
-struct remove_const<const T> { typedef T type; };
 
-// `remove_const_t<T>` removes any `const` specifier from `T`
-template<class T>
-using remove_const_t = typename remove_const<T>::type;
 
-template<class T>
-struct remove_reference { typedef T type; };
 
-template<class T>
-struct remove_reference<T &> { typedef T type; };
 
-template<class T>
-struct remove_reference<T &&> { typedef T type; };
 
-// `remove_reference_t<T>` removes any `&` from `T`
-template<class T>
-using remove_reference_t = typename remove_reference<T>::type;
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+#include "type_traits.h"
 
 namespace std
 {
@@ -344,8 +344,8 @@ namespace std {
 		void swap(pair& p) /*noexcept(...)*/;
 	};
 
-	template<class T1, class T2> constexpr pair<remove_reference_t<T1>, remove_reference_t<T2>> make_pair(T1&& x, T2&& y) {
-		return pair<T1, T2>(std::forward<T1>(x), std::forward<T2>(y));
+	template<class T1, class T2> constexpr pair<decay_t<T1>, decay_t<T2>> make_pair(T1&& x, T2&& y) {
+		return pair<decay_t<T1>, decay_t<T2>>(std::forward<T1>(x), std::forward<T2>(y));
 	}
 }
 
diff --git a/cpp/ql/test/library-tests/dataflow/taint-tests/type_traits.h b/cpp/ql/test/library-tests/dataflow/taint-tests/type_traits.h
@@ -0,0 +1,35 @@
+template<class T>
+struct remove_const { typedef T type; };
+
+template<class T>
+struct remove_const<const T> { typedef T type; };
+
+// `remove_const_t<T>` removes any `const` specifier from `T`
+template<class T>
+using remove_const_t = typename remove_const<T>::type;
+
+template<class T>
+struct remove_reference { typedef T type; };
+
+template<class T>
+struct remove_reference<T &> { typedef T type; };
+
+template<class T>
+struct remove_reference<T &&> { typedef T type; };
+
+// `remove_reference_t<T>` removes any `&` from `T`
+template<class T>
+using remove_reference_t = typename remove_reference<T>::type;
+
+template<class T>
+struct decay_impl {
+    typedef T type;
+};
+
+template<class T, size_t t_size>
+struct decay_impl<T[t_size]> {
+    typedef T* type;
+};
+
+template<class T>
+using decay_t = typename decay_impl<remove_reference_t<T>>::type;
