From cf3ea64b455e22009446f0d7cf6ca61683ee69e4 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Thu, 21 Feb 2019 21:57:39 +0200
Subject: [PATCH] Add reference specializations to variant_size

---
 include/boost/variant2/variant.hpp |  8 ++++++
 test/variant_size.cpp              | 40 ++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/include/boost/variant2/variant.hpp b/include/boost/variant2/variant.hpp
index 7050f98..2d41583 100644
--- a/include/boost/variant2/variant.hpp
+++ b/include/boost/variant2/variant.hpp
@@ -83,6 +83,14 @@ template<class T> struct variant_size<T const volatile>: variant_size<T>
 {
 };
 
+template<class T> struct variant_size<T&>: variant_size<T>
+{
+};
+
+template<class T> struct variant_size<T&&>: variant_size<T>
+{
+};
+
 #if !defined(BOOST_NO_CXX14_VARIABLE_TEMPLATES)
 
 template <class T> /*inline*/ constexpr std::size_t variant_size_v = variant_size<T>::value;
diff --git a/test/variant_size.cpp b/test/variant_size.cpp
index b348418..81e63ac 100644
--- a/test/variant_size.cpp
+++ b/test/variant_size.cpp
@@ -25,40 +25,80 @@ int main()
     BOOST_TEST_EQ( (variant_size<variant<> volatile>::value), 0 );
     BOOST_TEST_EQ( (variant_size<variant<> const volatile>::value), 0 );
 
+    BOOST_TEST_EQ( (variant_size<variant<>&>::value), 0 );
+    BOOST_TEST_EQ( (variant_size<variant<> const&>::value), 0 );
+    BOOST_TEST_EQ( (variant_size<variant<>&&>::value), 0 );
+    BOOST_TEST_EQ( (variant_size<variant<> const&&>::value), 0 );
+
     BOOST_TEST_EQ( (variant_size<variant<void>>::value), 1 );
     BOOST_TEST_EQ( (variant_size<variant<void> const>::value), 1 );
     BOOST_TEST_EQ( (variant_size<variant<void> volatile>::value), 1 );
     BOOST_TEST_EQ( (variant_size<variant<void> const volatile>::value), 1 );
 
+    BOOST_TEST_EQ( (variant_size<variant<void>&>::value), 1 );
+    BOOST_TEST_EQ( (variant_size<variant<void> const&>::value), 1 );
+    BOOST_TEST_EQ( (variant_size<variant<void>&&>::value), 1 );
+    BOOST_TEST_EQ( (variant_size<variant<void> const&&>::value), 1 );
+
     BOOST_TEST_EQ( (variant_size<variant<void, void>>::value), 2 );
     BOOST_TEST_EQ( (variant_size<variant<void, void> const>::value), 2 );
     BOOST_TEST_EQ( (variant_size<variant<void, void> volatile>::value), 2 );
     BOOST_TEST_EQ( (variant_size<variant<void, void> const volatile>::value), 2 );
 
+    BOOST_TEST_EQ( (variant_size<variant<void, void>&>::value), 2 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void> const&>::value), 2 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void>&&>::value), 2 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void> const&&>::value), 2 );
+
     BOOST_TEST_EQ( (variant_size<variant<void, void, void>>::value), 3 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void> const>::value), 3 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void> volatile>::value), 3 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void> const volatile>::value), 3 );
 
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void>&>::value), 3 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void> const&>::value), 3 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void>&&>::value), 3 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void> const&&>::value), 3 );
+
     BOOST_TEST_EQ( (variant_size<variant<void, void, void, void>>::value), 4 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void, void> const>::value), 4 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void, void> volatile>::value), 4 );
     BOOST_TEST_EQ( (variant_size<variant<void, void, void, void> const volatile>::value), 4 );
 
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void, void>&>::value), 4 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void, void> const&>::value), 4 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void, void>&&>::value), 4 );
+    BOOST_TEST_EQ( (variant_size<variant<void, void, void, void> const&&>::value), 4 );
+
     variant_size<void>();
     variant_size<void const>();
     variant_size<void volatile>();
     variant_size<void const volatile>();
 
+    variant_size<int&>();
+    variant_size<int const&>();
+    variant_size<int&&>();
+    variant_size<int const&&>();
+
     BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, void>));
     BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, void const>));
     BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, void volatile>));
     BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, void const volatile>));
 
+    BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, int&>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, int const&>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, int&&>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<var_size_t, int const&&>));
+
     BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<>>));
     BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<> const>));
     BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<> volatile>));
     BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<> const volatile>));
 
+    BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<>&>));
+    BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<> const&>));
+    BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<>&&>));
+    BOOST_TEST_TRAIT_TRUE((mp_valid<var_size_t, variant<> const&&>));
+
     return boost::report_errors();
 }