From f14309e92ddc5fd7f3263b25875cd62be2bb2711 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sun, 8 Dec 2019 02:07:17 +0200
Subject: [PATCH] Fix ambiguity in mp_similar<Y<>, Y<>>

---
 include/boost/mp11/function.hpp | 5 +++++
 test/mp_similar.cpp             | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/include/boost/mp11/function.hpp b/include/boost/mp11/function.hpp
index 8e1114a..1aeccac 100644
--- a/include/boost/mp11/function.hpp
+++ b/include/boost/mp11/function.hpp
@@ -188,6 +188,11 @@ template<template<class...> class L, class... T1, class... T2> struct mp_similar
     using type = mp_true;
 };
 
+template<template<class...> class L, class... T> struct mp_similar_impl<L<T...>, L<T...>>
+{
+    using type = mp_true;
+};
+
 template<class T1, class T2, class T3, class... T> struct mp_similar_impl<T1, T2, T3, T...>
 {
     using type = mp_all< typename mp_similar_impl<T1, T2>::type, typename mp_similar_impl<T1, T3>::type, typename mp_similar_impl<T1, T>::type... >;
diff --git a/test/mp_similar.cpp b/test/mp_similar.cpp
index 5fb538f..140c4ed 100644
--- a/test/mp_similar.cpp
+++ b/test/mp_similar.cpp
@@ -33,12 +33,17 @@ int main()
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<void, void, void, void, int>, mp_false>));
 
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<X<void>>, mp_true>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<X<void>, X<void>>, mp_true>));
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<X<void>, X<int>>, mp_true>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<X<void>, X<void>, X<void>>, mp_true>));
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<X<void>, X<int>, X<float>>, mp_true>));
 
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>>, mp_true>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<>>, mp_true>));
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<void>>, mp_true>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<>, Y<>>, mp_true>));
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<void>, Y<void, void>>, mp_true>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<>, Y<>, Y<>>, mp_true>));
     BOOST_TEST_TRAIT_TRUE((std::is_same<mp_similar<Y<>, Y<void>, Y<void, void>, Y<void, void, void>>, mp_true>));
 
     return boost::report_errors();