From fe653d0a9ae5f27fb8eca77d944aa44a5cc637b0 Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Sat, 20 Aug 2011 16:03:58 +0000
Subject: [PATCH] Change call_traits to pass enum's by value. Fixes #5790.

[SVN r73953]
---
 call_traits_test.cpp                 |  8 +++++++-
 include/boost/detail/call_traits.hpp | 20 ++++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/call_traits_test.cpp b/call_traits_test.cpp
index 72852c4..9e49b68 100644
--- a/call_traits_test.cpp
+++ b/call_traits_test.cpp
@@ -210,8 +210,10 @@ int main()
    comparible_UDT u;
    c1(u);
    call_traits_checker<int> c2;
+   call_traits_checker<enum_UDT> c2b;
    int i = 2;
    c2(i);
+   c2b(one);
    int* pi = &i;
    int a[2] = {1,2};
 #if defined(BOOST_MSVC6_MEMBER_TEMPLATES) && !defined(__ICL)
@@ -292,7 +294,11 @@ int main()
    BOOST_CHECK_TYPE(incomplete_type&, boost::call_traits<incomplete_type>::reference);
    BOOST_CHECK_TYPE(const incomplete_type&, boost::call_traits<incomplete_type>::const_reference);
    BOOST_CHECK_TYPE(const incomplete_type&, boost::call_traits<incomplete_type>::param_type);
-
+   // test enum:
+   BOOST_CHECK_TYPE(enum_UDT, boost::call_traits<enum_UDT>::value_type);
+   BOOST_CHECK_TYPE(enum_UDT&, boost::call_traits<enum_UDT>::reference);
+   BOOST_CHECK_TYPE(const enum_UDT&, boost::call_traits<enum_UDT>::const_reference);
+   BOOST_CHECK_TYPE(const enum_UDT, boost::call_traits<enum_UDT>::param_type);
    return 0;
 }
 
diff --git a/include/boost/detail/call_traits.hpp b/include/boost/detail/call_traits.hpp
index 6ad646e..36dea00 100644
--- a/include/boost/detail/call_traits.hpp
+++ b/include/boost/detail/call_traits.hpp
@@ -24,6 +24,7 @@
 #include <cstddef>
 
 #include <boost/type_traits/is_arithmetic.hpp>
+#include <boost/type_traits/is_enum.hpp>
 #include <boost/type_traits/is_pointer.hpp>
 #include <boost/detail/workaround.hpp>
 
@@ -43,20 +44,26 @@ struct ct_imp2<T, true>
    typedef const T param_type;
 };
 
-template <typename T, bool isp, bool b1>
+template <typename T, bool isp, bool b1, bool b2>
 struct ct_imp
 {
    typedef const T& param_type;
 };
 
-template <typename T, bool isp>
-struct ct_imp<T, isp, true>
+template <typename T, bool isp, bool b2>
+struct ct_imp<T, isp, true, b2>
 {
    typedef typename ct_imp2<T, sizeof(T) <= sizeof(void*)>::param_type param_type;
 };
 
-template <typename T, bool b1>
-struct ct_imp<T, true, b1>
+template <typename T, bool isp, bool b1>
+struct ct_imp<T, isp, b1, true>
+{
+   typedef typename ct_imp2<T, sizeof(T) <= sizeof(void*)>::param_type param_type;
+};
+
+template <typename T, bool b1, bool b2>
+struct ct_imp<T, true, b1, b2>
 {
    typedef const T param_type;
 };
@@ -79,7 +86,8 @@ public:
    typedef typename boost::detail::ct_imp<
       T,
       ::boost::is_pointer<T>::value,
-      ::boost::is_arithmetic<T>::value
+      ::boost::is_arithmetic<T>::value,
+      ::boost::is_enum<T>::value
    >::param_type param_type;
 };