3 files changed, 65 insertions, 22 deletions
diff --git a/googlemock/docs/cook_book.md b/googlemock/docs/cook_book.md
index a493521..7209ea0 100644
--- a/googlemock/docs/cook_book.md
+++ b/googlemock/docs/cook_book.md
@@ -2174,7 +2174,7 @@ own precedence order distinct from the `ON_CALL` precedence order.
 ### Using Functions/Methods/Functors/Lambdas as Actions {#FunctionsAsActions}
 
 If the built-in actions don't suit you, you can use an existing callable
-(function, `std::function`, method, functor, lambda as an action.
+(function, `std::function`, method, functor, lambda) as an action.
 
 <!-- GOOGLETEST_CM0024 DO NOT DELETE -->
 
@@ -2203,6 +2203,7 @@ class Helper {
       .WillRepeatedly(Invoke(NewPermanentCallback(Sum3, 1)));
   EXPECT_CALL(foo, ComplexJob(_))
       .WillOnce(Invoke(&helper, &Helper::ComplexJob))
+      .WillOnce([] { return true; })
       .WillRepeatedly([](int x) { return x > 0; });
 
   foo.Sum(5, 6);         // Invokes CalculateSum(5, 6).
@@ -2212,11 +2213,11 @@ class Helper {
 ```
 
 The only requirement is that the type of the function, etc must be *compatible*
-with the signature of the mock function, meaning that the latter's arguments can
-be implicitly converted to the corresponding arguments of the former, and the
-former's return type can be implicitly converted to that of the latter. So, you
-can invoke something whose type is *not* exactly the same as the mock function,
-as long as it's safe to do so - nice, huh?
+with the signature of the mock function, meaning that the latter's arguments (if
+it takes any) can be implicitly converted to the corresponding arguments of the
+former, and the former's return type can be implicitly converted to that of the
+latter. So, you can invoke something whose type is *not* exactly the same as the
+mock function, as long as it's safe to do so - nice, huh?
 
 **`Note:`{.escaped}**
 
@@ -2267,19 +2268,20 @@ TEST_F(FooTest, Test) {
 
 ### Invoking a Function/Method/Functor/Lambda/Callback Without Arguments
 
-`Invoke()` is very useful for doing actions that are more complex. It passes the
-mock function's arguments to the function, etc being invoked such that the
-callee has the full context of the call to work with. If the invoked function is
-not interested in some or all of the arguments, it can simply ignore them.
+`Invoke()` passes the mock function's arguments to the function, etc being
+invoked such that the callee has the full context of the call to work with. If
+the invoked function is not interested in some or all of the arguments, it can
+simply ignore them.
 
 Yet, a common pattern is that a test author wants to invoke a function without
-the arguments of the mock function. `Invoke()` allows her to do that using a
-wrapper function that throws away the arguments before invoking an underlining
-nullary function. Needless to say, this can be tedious and obscures the intent
-of the test.
+the arguments of the mock function. She could do that using a wrapper function
+that throws away the arguments before invoking an underlining nullary function.
+Needless to say, this can be tedious and obscures the intent of the test.
 
-`InvokeWithoutArgs()` solves this problem. It's like `Invoke()` except that it
-doesn't pass the mock function's arguments to the callee. Here's an example:
+There are two solutions to this problem. First, you can pass any callable of
+zero args as an action. Alternatively, use `InvokeWithoutArgs()`, which is like
+`Invoke()` except that it doesn't pass the mock function's arguments to the
+callee. Here's an example of each:
 
 ```cpp
 using ::testing::_;
@@ -2296,7 +2298,7 @@ bool Job2(int n, char c) { ... }
 ...
   MockFoo foo;
   EXPECT_CALL(foo, ComplexJob(_))
-      .WillOnce(InvokeWithoutArgs(Job1))
+      .WillOnce([] { Job1(); });
       .WillOnce(InvokeWithoutArgs(NewPermanentCallback(Job2, 5, 'a')));
 
   foo.ComplexJob(10);  // Invokes Job1().
diff --git a/googlemock/include/gmock/gmock-actions.h b/googlemock/include/gmock/gmock-actions.h
index e46bcaa..b4127e9 100644
--- a/googlemock/include/gmock/gmock-actions.h
+++ b/googlemock/include/gmock/gmock-actions.h
@@ -263,6 +263,10 @@ GMOCK_DEFINE_DEFAULT_ACTION_FOR_RETURN_TYPE_(double, 0);
 
 #undef GMOCK_DEFINE_DEFAULT_ACTION_FOR_RETURN_TYPE_
 
+// Simple two-arg form of std::disjunction.
+template <typename P, typename Q>
+using disjunction = typename ::std::conditional<P::value, P, Q>::type;
+
 }  // namespace internal
 
 // When an unexpected function call is encountered, Google Mock will
@@ -456,9 +460,15 @@ class Action {
   // This cannot take std::function directly, because then Action would not be
   // directly constructible from lambda (it would require two conversions).
   template <typename G,
-            typename = typename ::std::enable_if<
-                ::std::is_constructible<::std::function<F>, G>::value>::type>
-  Action(G&& fun) : fun_(::std::forward<G>(fun)) {}  // NOLINT
+            typename IsCompatibleFunctor =
+                ::std::is_constructible<::std::function<F>, G>,
+            typename IsNoArgsFunctor =
+                ::std::is_constructible<::std::function<Result()>, G>,
+            typename = typename ::std::enable_if<internal::disjunction<
+                IsCompatibleFunctor, IsNoArgsFunctor>::value>::type>
+  Action(G&& fun) {  // NOLINT
+    Init(::std::forward<G>(fun), IsCompatibleFunctor());
+  }
 
   // Constructs an Action from its implementation.
   explicit Action(ActionInterface<F>* impl)
@@ -490,6 +500,26 @@ class Action {
   template <typename G>
   friend class Action;
 
+  template <typename G>
+  void Init(G&& g, ::std::true_type) {
+    fun_ = ::std::forward<G>(g);
+  }
+
+  template <typename G>
+  void Init(G&& g, ::std::false_type) {
+    fun_ = IgnoreArgs<typename ::std::decay<G>::type>{::std::forward<G>(g)};
+  }
+
+  template <typename FunctionImpl>
+  struct IgnoreArgs {
+    template <typename... Args>
+    Result operator()(const Args&...) const {
+      return function_impl();
+    }
+
+    FunctionImpl function_impl;
+  };
+
   // fun_ is an empty function if and only if this is the DoDefault() action.
   ::std::function<F> fun_;
 };
diff --git a/googlemock/test/gmock-actions_test.cc b/googlemock/test/gmock-actions_test.cc
index 58a2d35..d1229ac 100644
--- a/googlemock/test/gmock-actions_test.cc
+++ b/googlemock/test/gmock-actions_test.cc
@@ -1470,8 +1470,19 @@ TEST(FunctorActionTest, TypeConversion) {
   EXPECT_EQ(1, s2.Perform(std::make_tuple("hello")));
 
   // Also between the lambda and the action itself.
-  const Action<bool(std::string)> x = [](Unused) { return 42; };
-  EXPECT_TRUE(x.Perform(std::make_tuple("hello")));
+  const Action<bool(std::string)> x1 = [](Unused) { return 42; };
+  const Action<bool(std::string)> x2 = [] { return 42; };
+  EXPECT_TRUE(x1.Perform(std::make_tuple("hello")));
+  EXPECT_TRUE(x2.Perform(std::make_tuple("hello")));
+
+  // Ensure decay occurs where required.
+  std::function<int()> f = [] { return 7; };
+  Action<int(int)> d = f;
+  f = nullptr;
+  EXPECT_EQ(7, d.Perform(std::make_tuple(1)));
+
+  // Ensure creation of an empty action succeeds.
+  Action<void(int)>(nullptr);
 }
 
 TEST(FunctorActionTest, UnusedArguments) {