gmock: improve SFINAE for actions involving arguments.

Avoid instantiating functions like std::get<index> for an out of range index
when doing SFINAE on the invocability of the action itself.

PiperOrigin-RevId: 439415110
Change-Id: Ifc20285a6d526c34830870cd1910c2b2b92e1e81

Author: Abseil Team

googlemock/include/gmock/gmock-actions.h

@@ -1077,7 +1077,8 @@ struct ReturnNewAction {
 
 template <size_t k>
 struct ReturnArgAction {
-  template <typename... Args>
+  template <typename... Args,
+            typename = typename std::enable_if<(k < sizeof...(Args))>::type>
   auto operator()(Args&&... args) const -> decltype(std::get<k>(
       std::forward_as_tuple(std::forward<Args>(args)...))) {
     return std::get<k>(std::forward_as_tuple(std::forward<Args>(args)...));

googlemock/include/gmock/gmock-more-actions.h

@@ -600,7 +600,8 @@ auto InvokeArgument(F f, Args... args) -> decltype(f(args...)) {
 
 template <std::size_t index, typename... Params>
 struct InvokeArgumentAction {
-  template <typename... Args>
+  template <typename... Args,
+            typename = typename std::enable_if<(index < sizeof...(Args))>::type>
   auto operator()(Args&&... args) const -> decltype(internal::InvokeArgument(
       std::get<index>(std::forward_as_tuple(std::forward<Args>(args)...)),
       std::declval<const Params&>()...)) {