diff --git a/include/boost/unordered/detail/foa/takes_arg_as_const_reference.hpp b/include/boost/unordered/detail/foa/takes_arg_as_const_reference.hpp
index 3a5c69d5..26cc7a57 100644
--- a/include/boost/unordered/detail/foa/takes_arg_as_const_reference.hpp
+++ b/include/boost/unordered/detail/foa/takes_arg_as_const_reference.hpp
@@ -18,75 +18,37 @@ namespace unordered{
 namespace detail{
 namespace foa{
 
-static constexpr bool noexcept_is_part_of_signature=
-  !std::is_same<void(*)(),void(*)()noexcept>::value;
-
-template<typename Arg,typename Sig>
-static std::false_type has_1st_arg(Sig);
+template<typename Arg,typename R,typename... Args>
+void check_function_1st_arg(R(*)(Arg,Args...));
 
 template<typename Arg,typename R,typename... Args>
-static std::true_type has_1st_arg(R(*)(Arg,Args...));
+void check_function_1st_arg(R(*)(Arg,Args...,...));
 
-template<
-  typename Arg,typename R,typename... Args,
-  bool dependent_value=false,
-  typename std::enable_if<
-    noexcept_is_part_of_signature||dependent_value>::type* =nullptr
->
-static std::true_type has_1st_arg(R(*)(Arg,Args...)noexcept);
-
-template<typename Arg,typename R,typename... Args>
-static std::true_type has_1st_arg(R(*)(Arg,Args...,...));
-
-template<
-  typename Arg,typename R,typename... Args,
-  bool dependent_value=false,
-  typename std::enable_if<
-    noexcept_is_part_of_signature||dependent_value>::type* =nullptr
->
-std::true_type has_1st_arg(R(*)(Arg,Args...,...)noexcept);
-
-#define BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(qualifier)             \
-template<typename Arg,typename R,typename C,typename... Args>                 \
-static std::true_type has_1st_arg(R(C::*)(Arg,Args...)qualifier);             \
-                                                                              \
-template<                                                                     \
-  typename Arg,typename R,typename C,typename... Args,                        \
-  bool dependent_value=false,                                                 \
-  typename std::enable_if<                                                    \
-    noexcept_is_part_of_signature||dependent_value>::type* =nullptr           \
->                                                                             \
-static std::true_type has_1st_arg(R(C::*)(Arg,Args...)qualifier noexcept);    \
-                                                                              \
-template<typename Arg,typename R,typename C,typename... Args>                 \
-static std::true_type has_1st_arg(R(C::*)(Arg,Args...,...)qualifier);         \
-                                                                              \
-template<                                                                     \
-  typename Arg,typename R,typename C,typename... Args,                        \
-  bool dependent_value=false,                                                 \
-  typename std::enable_if<                                                    \
-    noexcept_is_part_of_signature||dependent_value>::type* =nullptr           \
->                                                                             \
-static std::true_type has_1st_arg(R(C::*)(Arg,Args...,...)qualifier noexcept);
+#define BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(qualifier)       \
+template<typename Arg,typename R,typename C,typename... Args> \
+void check_memfun_1st_arg(R(C::*)(Arg,Args...)qualifier);     \
+                                                              \
+template<typename Arg,typename R,typename C,typename... Args> \
+void check_memfun_1st_arg(R(C::*)(Arg,Args...,...)qualifier);
 
 /* VS warns when a pp function is directly called with an empty arg */
 #define BOOST_UNORDERED_EMPTY_PP_ARG()
 
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(BOOST_UNORDERED_EMPTY_PP_ARG())
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(volatile)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const volatile)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(volatile&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const volatile&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(&&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const&&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(volatile&&)
-BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const volatile&&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(BOOST_UNORDERED_EMPTY_PP_ARG())
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(volatile)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const volatile)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(volatile&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const volatile&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(&&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const&&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(volatile&&)
+BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG(const volatile&&)
 
 #undef BOOST_UNORDERED_EMPTY_PP_ARG
-#undef BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN
+#undef BOOST_UNORDERED_CHECK_MEMFUN_1ST_ARG
 
 /* Detects if f(x) takes x as a const reference. From an implementation
  * technique by Kenneth Gorking.
@@ -94,29 +56,41 @@ BOOST_UNORDERED_HAS_CONST_REFERENCE_ARG_MEMFUN(const volatile&&)
  */
 
 template<typename F,typename Arg,typename=void>
-struct takes_arg_as_const_reference0:
-decltype(has_1st_arg<const Arg&>(std::declval<F>())){};
+struct takes_arg_as_const_reference0:std::false_type{};
 
 template<typename F,typename Arg>
 struct takes_arg_as_const_reference0<
   F,Arg,
   boost::void_t<
-    decltype(has_1st_arg<const Arg&>(&F::template operator()<Arg>))
+    decltype(check_function_1st_arg<const Arg&>(std::declval<F>()))
   >
->:
-decltype(has_1st_arg<const Arg&>(&F::template operator()<Arg>)){};
+>:std::true_type{};
+
+template<typename F,typename Arg>
+struct takes_arg_as_const_reference0<
+  F,Arg,
+  boost::void_t<
+    decltype(std::declval<F>().operator()(std::declval<Arg&>()))
+  >
+>:std::true_type{};
 
 template<typename F,typename Arg,typename=void>
 struct takes_arg_as_const_reference:takes_arg_as_const_reference0<F,Arg>{};
 
+template<
+  typename F,typename Arg,
+  typename R=decltype(std::declval<F>()(std::declval<Arg&>())),
+  typename RawF=
+    typename std::remove_cv<typename std::remove_reference<F>::type>::type
+>
+using check_operator_call_takes_arg_as_reference=
+  decltype(check_memfun_1st_arg<Arg&,R,RawF>(&RawF::operator()));
+
 template<typename F,typename Arg>
 struct takes_arg_as_const_reference<
   F,Arg,
-  boost::void_t<
-    decltype(has_1st_arg<const Arg&>(&F::operator()))
-  >
->:
-decltype(has_1st_arg<const Arg&>(&F::operator())){};
+  boost::void_t<check_operator_call_takes_arg_as_reference<F,Arg>>
+>:std::false_type{};
 
 } /* namespace foa */
 } /* namespace detail */
diff --git a/test/cfoa/takes_arg_as_cref_tests.cpp b/test/cfoa/takes_arg_as_cref_tests.cpp
index 2cfa1b05..2d7500f0 100644
--- a/test/cfoa/takes_arg_as_cref_tests.cpp
+++ b/test/cfoa/takes_arg_as_cref_tests.cpp
@@ -78,9 +78,9 @@ int main()
     int   retrieved=0;
     auto  lambda54 = [&]( const int& x ) mutable { retrieved = x; };
     using f54=decltype(lambda54);
-    auto  lambda55 = []( int& ){};
+    auto  lambda55 = []( int& x ){ x = 0; };
     using f55=decltype(lambda55);
-    auto  lambda56 = [&]( int& x ) mutable { retrieved = x; };
+    auto  lambda56 = [&]( int& x ) mutable { retrieved = x; x = 0; };
     using f56=decltype(lambda56);
 
 #if !defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
@@ -88,90 +88,90 @@ int main()
     using f57=decltype(lambda57);
     auto  lambda58 = [&]( const auto& x ) mutable { retrieved = x; };
     using f58=decltype(lambda58);
-    auto  lambda59 = []( auto& ){};
+    auto  lambda59 = []( auto& x ){ x = 0; };
     using f59=decltype(lambda59);
-    auto  lambda60 = [&]( auto& x ) mutable { retrieved = x; };
+    auto  lambda60 = [&]( auto& x ) mutable { retrieved = x; x = 0; };
     using f60=decltype(lambda60);
 #endif
 
-    BOOST_TEST((  takes_arg_as_const_reference<f1,  int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f2,  int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f3,  int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f4,  int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f5,  int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f6,  int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f7,  int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f8,  int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f1*, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f2*, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f3*, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f4*, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f5*, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f6*, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f7*, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f8*, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f1&, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f2&, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f3&, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f4&, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f5&, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f6&, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f7&, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f8&, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f9,  int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f10, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f11, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f12, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f13, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f14, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f15, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f16, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f17, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f18, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f19, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f20, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f21, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f22, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f23, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f24, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f25, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f26, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f27, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f28, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f29, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f30, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f31, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f32, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f33, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f34, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f35, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f36, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f37, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f38, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f39, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f40, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f41, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f42, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f43, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f44, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f45, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f46, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f47, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f48, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f49, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f50, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f51, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f52, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f53, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f54, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f55, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f56, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f1,    int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f2,    int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f3,    int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f4,    int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f5,    int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f6,    int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f7,    int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f8,    int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f1*,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f2*,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f3*,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f4*,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f5*,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f6*,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f7*,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f8*,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f1&,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f2&,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f3&,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f4&,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f5&,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f6&,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f7&,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f8&,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f9,    int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f10,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f11,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f12,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f13&,  int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f14&,  int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f15&,  int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f16&,  int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f17&&, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f18&&, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f19&&, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f20&&, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f21,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f22,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f23,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f24,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f25,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f26,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f27,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f28,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f29&,  int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f30&,  int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f31&,  int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f32&,  int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f33&&, int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f34&&, int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f35&&, int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f36&&, int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f37,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f38,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f39,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f40,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f41,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f42,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f43,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f44,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f45,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f46,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f47,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f48,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f49,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f50,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f51,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f52,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f53,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f54,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f55,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f56,   int>::value ));
 
 #if !defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
-    BOOST_TEST((  takes_arg_as_const_reference<f57, int>::value ));
-    BOOST_TEST((  takes_arg_as_const_reference<f58, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f59, int>::value ));
-    BOOST_TEST(( !takes_arg_as_const_reference<f60, int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f57,   int>::value ));
+    BOOST_TEST((  takes_arg_as_const_reference<f58,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f59,   int>::value ));
+    BOOST_TEST(( !takes_arg_as_const_reference<f60,   int>::value ));
 #endif
 
     return boost::report_errors();