From 2bee266adf5b35c3c80b1e5b7224c0e3bdd8f2a8 Mon Sep 17 00:00:00 2001
From: Esteve Fernandez <esteve@apache.org>
Date: Fri, 14 Jun 2019 22:09:47 +0200
Subject: [PATCH] Added support for const member functions (#763)

* Added support for const member functions

Signed-off-by: Esteve Fernandez <esteve@apache.org>

* Added signature for Windows

Signed-off-by: Esteve Fernandez <esteve@apache.org>

* Fix style

Signed-off-by: Esteve Fernandez <esteve@apache.org>

* Attempt at fixing function_traits for macOS

Signed-off-by: Esteve Fernandez <esteve@apache.org>
---
 rclcpp/include/rclcpp/function_traits.hpp | 18 +++++++++++++++++
 rclcpp/test/test_function_traits.cpp      | 24 +++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/rclcpp/include/rclcpp/function_traits.hpp b/rclcpp/include/rclcpp/function_traits.hpp
index 4ccfc75..3599df5 100644
--- a/rclcpp/include/rclcpp/function_traits.hpp
+++ b/rclcpp/include/rclcpp/function_traits.hpp
@@ -96,6 +96,24 @@ struct function_traits<
   : function_traits<ReturnTypeT(Args ...)>
 {};
 
+// std::bind for object const methods
+template<typename ClassT, typename ReturnTypeT, typename ... Args, typename ... FArgs>
+#if defined _LIBCPP_VERSION  // libc++ (Clang)
+struct function_traits<std::__bind<ReturnTypeT (ClassT::*)(Args ...) const, FArgs ...>>
+#elif defined _GLIBCXX_RELEASE  // glibc++ (GNU C++ >= 7.1)
+struct function_traits<std::_Bind<ReturnTypeT(ClassT::*(FArgs ...))(Args ...) const>>
+#elif defined __GLIBCXX__  // glibc++ (GNU C++)
+struct function_traits<std::_Bind<std::_Mem_fn<ReturnTypeT (ClassT::*)(Args ...) const>(FArgs ...)>>
+#elif defined _MSC_VER  // MS Visual Studio
+struct function_traits<
+  std::_Binder<std::_Unforced, ReturnTypeT(__cdecl ClassT::*)(Args ...) const, FArgs ...>
+>
+#else
+#error "Unsupported C++ compiler / standard library"
+#endif
+  : function_traits<ReturnTypeT(Args ...)>
+{};
+
 // std::bind for free functions
 template<typename ReturnTypeT, typename ... Args, typename ... FArgs>
 #if defined _LIBCPP_VERSION  // libc++ (Clang)
diff --git a/rclcpp/test/test_function_traits.cpp b/rclcpp/test/test_function_traits.cpp
index 4e09b08..d166ed2 100644
--- a/rclcpp/test/test_function_traits.cpp
+++ b/rclcpp/test/test_function_traits.cpp
@@ -80,6 +80,12 @@ struct ObjectMember
     return 7;
   }
 
+  int callback_one_bool_const(bool a) const
+  {
+    (void)a;
+    return 7;
+  }
+
   int callback_two_bools(bool a, bool b)
   {
     (void)a;
@@ -394,6 +400,16 @@ TEST(TestFunctionTraits, argument_types) {
       rclcpp::function_traits::function_traits<decltype(bind_one_bool)>::template argument_type<0>
     >::value, "Functor accepts a bool as first argument");
 
+  auto bind_one_bool_const = std::bind(
+    &ObjectMember::callback_one_bool_const, &object_member, std::placeholders::_1);
+
+  static_assert(
+    std::is_same<
+      bool,
+      rclcpp::function_traits::function_traits<decltype(bind_one_bool_const)>::template
+      argument_type<0>
+    >::value, "Functor accepts a bool as first argument");
+
   auto bind_two_bools = std::bind(
     &ObjectMember::callback_two_bools, &object_member, std::placeholders::_1,
     std::placeholders::_2);
@@ -561,6 +577,14 @@ TEST(TestFunctionTraits, check_arguments) {
   static_assert(
     rclcpp::function_traits::check_arguments<decltype(bind_one_bool), bool>::value,
     "Functor accepts a single bool as arguments");
+
+  auto bind_one_bool_const = std::bind(
+    &ObjectMember::callback_one_bool_const, &object_member, std::placeholders::_1);
+
+  // Test std::bind functions
+  static_assert(
+    rclcpp::function_traits::check_arguments<decltype(bind_one_bool_const), bool>::value,
+    "Functor accepts a single bool as arguments");
 }
 
 /*