Make mp_rename, mp_apply, mp_apply_q SFINAE-friendly

test/Jamfile

@@ -41,6 +41,7 @@ run mp_replace_front.cpp ;
 run mp_replace_second.cpp ;
 run mp_replace_third.cpp ;
 run mp_apply_q.cpp ;
+run mp_apply_q_sf.cpp ;
 run mp_is_list.cpp ;
 run mp_list_c.cpp ;
 run mp_transform_front.cpp ;

test/mp_apply_q_sf.cpp

@@ -0,0 +1,49 @@
+// Copyright 2015, 2017, 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+#include <boost/mp11/detail/config.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+
+using boost::mp11::mp_apply_q;
+using boost::mp11::mp_list;
+using boost::mp11::mp_quote;
+using boost::mp11::mp_quote_trait;
+using boost::mp11::mp_valid;
+using boost::mp11::mp_identity;
+using boost::mp11::mp_identity_t;
+
+int main()
+{
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, void>));
+
+#if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )
+
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, void, void>));
+
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, void, mp_list<>>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, void, mp_list<void>>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, void, mp_list<void, void>>));
+
+#endif
+
+    using Qi = mp_quote<mp_identity_t>;
+
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, Qi, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((mp_valid<mp_apply_q, Qi, mp_list<void>>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, Qi, mp_list<void, void>>));
+
+    using Qt = mp_quote_trait<mp_identity>;
+
+#if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, Qt, mp_list<>>));
+#endif
+    BOOST_TEST_TRAIT_TRUE((mp_valid<mp_apply_q, Qt, mp_list<void>>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_apply_q, Qt, mp_list<void, void>>));
+
+    return boost::report_errors();
+}