Googletest export

Addressing https://github.com/google/googletest/issues/2502

Add MOCK_METHOD support for returning function pointers.

PiperOrigin-RevId: 275323671

googlemock/include/gmock/gmock-function-mocker.h

@@ -39,6 +39,13 @@
 #include "gmock/gmock-generated-function-mockers.h"  // NOLINT
 #include "gmock/internal/gmock-pp.h"
 
+namespace testing {
+namespace internal {
+template <typename T>
+using identity_t = T;
+}  // namespace internal
+}  // namespace testing
+
 #define MOCK_METHOD(...) \
   GMOCK_PP_VARIADIC_CALL(GMOCK_INTERNAL_MOCK_METHOD_ARG_, __VA_ARGS__)
 
@@ -207,10 +214,24 @@
 
 #define GMOCK_INTERNAL_IS_CALLTYPE_HELPER_Calltype
 
-#define GMOCK_INTERNAL_SIGNATURE(_Ret, _Args)                         \
-  GMOCK_PP_IF(GMOCK_PP_IS_BEGIN_PARENS(_Ret), GMOCK_PP_REMOVE_PARENS, \
-              GMOCK_PP_IDENTITY)                                      \
-  (_Ret)(GMOCK_PP_FOR_EACH(GMOCK_INTERNAL_GET_TYPE, _, _Args))
+// Note: The use of `identity_t` here allows _Ret to represent return types that
+// would normally need to be specified in a different way. For example, a method
+// returning a function pointer must be written as
+//
+// fn_ptr_return_t (*method(method_args_t...))(fn_ptr_args_t...)
+//
+// But we only support placing the return type at the beginning. To handle this,
+// we wrap all calls in identity_t, so that a declaration will be expanded to
+//
+// identity_t<fn_ptr_return_t (*)(fn_ptr_args_t...)> method(method_args_t...)
+//
+// This allows us to work around the syntactic oddities of function/method
+// types.
+#define GMOCK_INTERNAL_SIGNATURE(_Ret, _Args)                                 \
+  ::testing::internal::identity_t<GMOCK_PP_IF(GMOCK_PP_IS_BEGIN_PARENS(_Ret), \
+                                              GMOCK_PP_REMOVE_PARENS,         \
+                                              GMOCK_PP_IDENTITY)(_Ret)>(      \
+      GMOCK_PP_FOR_EACH(GMOCK_INTERNAL_GET_TYPE, _, _Args))
 
 #define GMOCK_INTERNAL_GET_TYPE(_i, _, _elem)                          \
   GMOCK_PP_COMMA_IF(_i)                                                \