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Addressing #2502 Add MOCK_METHOD support for returning function pointers. PiperOrigin-RevId: 275323671
google · Oct 18, 2019 · 1f9edcd · 1f9edcd
1 parent bbe4b73
commit 1f9edcd
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Showing 2 changed files with 32 additions and 4 deletions.
diff --git a/googlemock/include/gmock/gmock-function-mocker.h b/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)                                                \

diff --git a/googlemock/test/gmock-function-mocker_test.cc b/googlemock/test/gmock-function-mocker_test.cc
@@ -101,6 +101,10 @@ class FooInterface {
   virtual int TypeWithComma(const std::map<int, std::string>& a_map) = 0;
   virtual int TypeWithTemplatedCopyCtor(const TemplatedCopyable<int>&) = 0;
 
+  virtual int (*ReturnsFunctionPointer1(int))(bool) = 0;
+  using fn_ptr = int (*)(bool);
+  virtual fn_ptr ReturnsFunctionPointer2(int) = 0;
+
 #if GTEST_OS_WINDOWS
   STDMETHOD_(int, CTNullary)() = 0;
   STDMETHOD_(bool, CTUnary)(int x) = 0;
@@ -159,6 +163,9 @@ class MockFoo : public FooInterface {
   MOCK_METHOD(int, TypeWithTemplatedCopyCtor,
               (const TemplatedCopyable<int>&));  // NOLINT
 
+  MOCK_METHOD(int (*)(bool), ReturnsFunctionPointer1, (int), ());
+  MOCK_METHOD(fn_ptr, ReturnsFunctionPointer2, (int), ());
+
 #if GTEST_OS_WINDOWS
   MOCK_METHOD(int, CTNullary, (), (Calltype(STDMETHODCALLTYPE)));
   MOCK_METHOD(bool, CTUnary, (int), (Calltype(STDMETHODCALLTYPE)));