Support const callables

Fixes #2

Author: TartanLlama

CMakeLists.txt

@@ -11,6 +11,7 @@ target_include_directories(Catch INTERFACE ${CATCH_INCLUDE_DIR})
 set(TEST_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/tests/main.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/tests/constructors.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/tests/call.cpp  
+  ${CMAKE_CURRENT_SOURCE_DIR}/tests/issues.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/tests/assignment.cpp)
 
 add_executable(tests ${TEST_SOURCES})

function_ref.hpp

@@ -15,7 +15,7 @@
 #define TL_FUNCTION_REF_HPP
 
 #define TL_FUNCTION_REF_VERSION_MAJOR 0
-#define TL_FUNCTION_REF_VERSION_MINOR 1
+#define TL_FUNCTION_REF_VERSION_MINOR 2
 
 #if (defined(_MSC_VER) && _MSC_VER == 1900)
 /// \exclude
@@ -151,7 +151,7 @@ template <class R, class... Args> class function_ref<R(Args...)> {
                 !std::is_same<detail::decay_t<F>, function_ref>::value &&
                 detail::is_invocable_r<R, F &&, Args...>::value> * = nullptr>
   TL_FUNCTION_REF_11_CONSTEXPR function_ref(F &&f) noexcept
-      : obj_(reinterpret_cast<void *>(std::addressof(f))) {
+      : obj_(const_cast<void*>(reinterpret_cast<const void *>(std::addressof(f)))) {
     callback_ = [](void *obj, Args... args) {
       return detail::invoke(
           *reinterpret_cast<typename std::add_pointer<F>::type>(obj),

tests/issues.cpp

@@ -0,0 +1,7 @@
+#include "catch.hpp"
+#include "function_ref.hpp"
+
+TEST_CASE("Issue #2") {
+	const auto lam = [](int x) {};
+	tl::function_ref<void(int)> ref = lam;
+}