Remove a pre-C++17 workaround for std::is_invocable_r

Builds/CMake/RippledCore.cmake

@@ -278,10 +278,6 @@ install (
     src/ripple/beast/crypto/ripemd.h
     src/ripple/beast/crypto/sha2.h
   DESTINATION include/ripple/beast/crypto)
-install (
-  FILES
-    src/ripple/beast/cxx17/type_traits.h
-  DESTINATION include/ripple/beast/cxx17)
 install (
   FILES
     src/ripple/beast/hash/endian.h

src/ripple/basics/XRPAmount.h

@@ -22,7 +22,6 @@
 
 #include <ripple/basics/contract.h>
 #include <ripple/basics/safe_cast.h>
-#include <ripple/beast/cxx17/type_traits.h>
 #include <ripple/beast/utility/Zero.h>
 #include <ripple/json/json_value.h>
 
@@ -32,6 +31,7 @@
 
 #include <cstdint>
 #include <string>
+#include <type_traits>
 
 namespace ripple {
 

src/ripple/basics/base_uint.h

@@ -27,7 +27,6 @@
 
 #include <ripple/basics/hardened_hash.h>
 #include <ripple/basics/strHex.h>
-#include <ripple/beast/cxx17/type_traits.h>
 #include <ripple/beast/utility/Zero.h>
 #include <boost/endian/conversion.hpp>
 #include <boost/functional/hash.hpp>

src/ripple/basics/random.h

@@ -20,7 +20,6 @@
 #ifndef RIPPLE_BASICS_RANDOM_H_INCLUDED
 #define RIPPLE_BASICS_RANDOM_H_INCLUDED
 
-#include <ripple/beast/cxx17/type_traits.h>  // <type_traits>
 #include <ripple/beast/xor_shift_engine.h>
 #include <cassert>
 #include <cstddef>
@@ -29,6 +28,7 @@
 #include <limits>
 #include <mutex>
 #include <random>
+#include <type_traits>
 
 namespace ripple {
 

src/ripple/basics/safe_cast.h

@@ -20,7 +20,6 @@
 #ifndef RIPPLE_BASICS_SAFE_CAST_H_INCLUDED
 #define RIPPLE_BASICS_SAFE_CAST_H_INCLUDED
 
-#include <ripple/beast/cxx17/type_traits.h>
 #include <type_traits>
 
 namespace ripple {

src/ripple/beast/container/detail/aged_ordered_container.h

@@ -25,7 +25,6 @@
 #include <ripple/beast/container/detail/aged_associative_container.h>
 #include <ripple/beast/container/detail/aged_container_iterator.h>
 #include <ripple/beast/container/detail/empty_base_optimization.h>
-#include <ripple/beast/cxx17/type_traits.h>  // <type_traits>
 #include <boost/intrusive/list.hpp>
 #include <boost/intrusive/set.hpp>
 #include <boost/version.hpp>
@@ -34,6 +33,7 @@
 #include <initializer_list>
 #include <iterator>
 #include <memory>
+#include <type_traits>
 #include <utility>
 
 namespace beast {

src/ripple/beast/cxx17/type_traits.h

@@ -1,41 +0,0 @@
-//------------------------------------------------------------------------------
-/*
-    This file is part of Beast: https://github.com/vinniefalco/Beast
-    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
-
-    Permission to use, copy, modify, and/or distribute this software for any
-    purpose  with  or without fee is hereby granted, provided that the above
-    copyright notice and this permission notice appear in all copies.
-
-    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
-    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
-    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-*/
-//==============================================================================
-
-#ifndef BEAST_CXX17_TYPE_TRAITS_H_INCLUDED
-#define BEAST_CXX17_TYPE_TRAITS_H_INCLUDED
-
-#include <tuple>
-#include <type_traits>
-#include <utility>
-
-#if defined(_LIBCPP_VERSION) && _LIBCPP_VERSION < 6000
-
-namespace std {
-
-template <class _Ret, class _Fn, class... _Args>
-struct _LIBCPP_TEMPLATE_VIS is_invocable_r
-    : integral_constant<bool, __invokable_r<_Ret, _Fn, _Args...>::value>
-{
-};
-
-}  // namespace std
-
-#endif
-
-#endif

src/test/jtx/Env.h

@@ -26,7 +26,6 @@
 #include <ripple/app/paths/Pathfinder.h>
 #include <ripple/basics/Log.h>
 #include <ripple/basics/chrono.h>
-#include <ripple/beast/cxx17/type_traits.h>  // <type_traits>
 #include <ripple/beast/utility/Journal.h>
 #include <ripple/core/Config.h>
 #include <ripple/json/json_value.h>
@@ -50,6 +49,7 @@
 #include <test/jtx/tags.h>
 #include <test/unit_test/SuiteJournal.h>
 #include <tuple>
+#include <type_traits>
 #include <unordered_map>
 #include <utility>
 #include <vector>