From 8615aed8e8605038ab94406810eb34c11c0470c4 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Mon, 15 May 2023 17:30:09 +0300
Subject: [PATCH] Add support for value lists to mp_push_back. Refs #53.

---
 include/boost/mp11/list.hpp |  9 ++++++++
 test/Jamfile                |  1 +
 test/mp_push_back_2.cpp     | 46 +++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 test/mp_push_back_2.cpp

diff --git a/include/boost/mp11/list.hpp b/include/boost/mp11/list.hpp
index a003ee5..90d5e7d 100644
--- a/include/boost/mp11/list.hpp
+++ b/include/boost/mp11/list.hpp
@@ -239,6 +239,15 @@ template<template<class...> class L, class... U, class... T> struct mp_push_back
     using type = L<U..., T...>;
 };
 
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+template<template<auto...> class L, auto... A, class... T> struct mp_push_back_impl<L<A...>, T...>
+{
+    using type = L<A..., T::value...>;
+};
+
+#endif
+
 } // namespace detail
 
 template<class L, class... T> using mp_push_back = typename detail::mp_push_back_impl<L, T...>::type;
diff --git a/test/Jamfile b/test/Jamfile
index cf3100d..c307048 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -44,6 +44,7 @@ run mp_third_2.cpp ;
 run mp_push_front.cpp ;
 run mp_push_front_2.cpp ;
 run mp_push_back.cpp ;
+run mp_push_back_2.cpp ;
 run mp_rename.cpp ;
 run mp_rename_2.cpp ;
 run mp_append.cpp ;
diff --git a/test/mp_push_back_2.cpp b/test/mp_push_back_2.cpp
new file mode 100644
index 0000000..2a7a3c1
--- /dev/null
+++ b/test/mp_push_back_2.cpp
@@ -0,0 +1,46 @@
+// Copyright 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>
+
+#if !defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+#pragma message("Test skipped because BOOST_MP11_HAS_TEMPLATE_AUTO is not defined")
+int main() {}
+
+#else
+
+#include <boost/mp11/integral.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+
+template<auto... A> struct L1 {};
+template<int... I> struct L2 {};
+
+int main()
+{
+    using boost::mp11::mp_push_back;
+    using boost::mp11::mp_true;
+    using boost::mp11::mp_false;
+    using boost::mp11::mp_int;
+
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<>>, L1<>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<>, mp_false>, L1<false>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<>, mp_false, mp_true>, L1<false, true>);
+
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<-1, -2>>, L1<-1, -2>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<-1, -2>, mp_false>, L1<-1, -2, false>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L1<-1, -2>, mp_false, mp_true>, L1<-1, -2, false, true>);
+
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<>>, L2<>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<>, mp_int<0>>, L2<0>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<>, mp_int<0>, mp_int<1>>, L2<0, 1>);
+
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<-1, -2>>, L2<-1, -2>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<-1, -2>, mp_int<0>>, L2<-1, -2, 0>);
+    BOOST_TEST_TRAIT_SAME(mp_push_back<L2<-1, -2>, mp_int<0>, mp_int<1>>, L2<-1, -2, 0, 1>);
+
+    return boost::report_errors();
+}
+
+#endif