Add test

Author: DimitrijeDobrota

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/missing-std-forward-custom-function.cpp

@@ -0,0 +1,42 @@
+// RUN: %check_clang_tidy -std=c++14 %s cppcoreguidelines-missing-std-forward %t -- \
+// RUN: -config="{CheckOptions: {cppcoreguidelines-missing-std-forward.ForwardFunction: custom_forward}}" -- -fno-delayed-template-parsing
+
+// NOLINTBEGIN
+namespace std {
+
+template <typename T> struct remove_reference      { using type = T; };
+template <typename T> struct remove_reference<T&>  { using type = T; };
+template <typename T> struct remove_reference<T&&> { using type = T; };
+
+template <typename T> using remove_reference_t = typename remove_reference<T>::type;
+
+template <typename T> constexpr T &&forward(remove_reference_t<T> &t) noexcept;
+template <typename T> constexpr T &&forward(remove_reference_t<T> &&t) noexcept;
+template <typename T> constexpr remove_reference_t<T> &&move(T &&x);
+
+} // namespace std
+// NOLINTEND
+
+template<class T>
+constexpr decltype(auto) custom_forward(std::remove_reference_t<T>& tmp) noexcept
+{
+  return static_cast<T&&>(tmp);
+}
+
+template<class T>
+constexpr decltype(auto) custom_forward(std::remove_reference_t<T>&& tmp) noexcept
+{
+  return static_cast<T&&>(tmp);
+}
+
+template<class T>
+void forward_with_std(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+
+  T other{std::forward<T>(t)};
+}
+
+template<class T>
+void move_with_custom(T&& t) {
+  T other{custom_forward<T>(t)};
+}