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Added decaying to common_type in accordance with defect LWG2141

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This commit is contained in:
AntonBikineev
2015-05-20 10:29:22 -05:00
parent ba1588ebc1
commit 34fe226814
2 changed files with 22 additions and 5 deletions
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21
include/boost/type_traits/common_type.hpp
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@ -42,6 +42,9 @@
#include <boost/type_traits/add_rvalue_reference.hpp>
#endif
#include <boost/type_traits/remove_cv.hpp>
#include <boost/type_traits/decay.hpp>
//----------------------------------------------------------------------------//
// //
// C++03 implementation of //
@ -53,6 +56,14 @@
namespace boost {
namespace type_traits_detail {
template <class T>
struct std_decay: boost::remove_cv<
typename boost::decay<T>::type> {};
}
// prototype
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
template<typename... T>
@ -78,7 +89,7 @@ namespace boost {
{
BOOST_STATIC_ASSERT_MSG(sizeof(T) > 0, "The template arguments to common_type must be complete types");
public:
typedef T type;
typedef typename type_traits_detail::std_decay<T>::type type;
};
// 2 args
@ -93,13 +104,13 @@ namespace type_traits_detail {
#if !defined(BOOST_NO_CXX11_DECLTYPE)
public:
typedef decltype(declval<bool>() ? declval<T>() : declval<U>()) type;
typedef typename std_decay<decltype(declval<bool>() ? declval<T>() : declval<U>())>::type type;
#elif defined(BOOST_COMMON_TYPE_USE_TYPEOF)
static typename add_rvalue_reference<T>::type declval_T(); // workaround gcc bug; not required by std
static typename add_rvalue_reference<U>::type declval_U(); // workaround gcc bug; not required by std
static typename add_rvalue_reference<bool>::type declval_b();
public:
typedef __typeof__(declval_b() ? declval_T() : declval_U()) type;
typedef typename std_decay<__typeof__(declval_b() ? declval_T() : declval_U())>::type type;
#elif defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF)
public:
typedef typename detail_type_traits_common_type::common_type_impl<
@ -111,7 +122,7 @@ namespace type_traits_detail {
static typename add_rvalue_reference<U>::type declval_U(); // workaround gcc bug; not required by std
static typename add_rvalue_reference<bool>::type declval_b();
public:
typedef BOOST_TYPEOF_TPL(declval_b() ? declval_T() : declval_U()) type;
typedef typename std_decay<BOOST_TYPEOF_TPL(declval_b() ? declval_T() : declval_U())>::type type;
#endif
#if defined(__GNUC__) && __GNUC__ == 3 && __GNUC_MINOR__ == 3
@ -123,7 +134,7 @@ namespace type_traits_detail {
template <class T>
struct common_type_2<T, T>
{
typedef T type;
typedef typename type_traits_detail::std_decay<T>::type type;
};
}

6
test/common_type_test.cpp
View File

@ -211,5 +211,11 @@ TT_TEST_BEGIN(common_type)
#ifndef BOOST_NO_LONG_LONG
BOOST_CHECK_TYPE4(tt::common_type<unsigned, char, boost::long_long_type>::type, boost::long_long_type);
#endif
//changes related to defect LWG2141
BOOST_CHECK_TYPE(tt::common_type<int&>::type, int);
BOOST_CHECK_TYPE(tt::common_type<const int>::type, int);
BOOST_CHECK_TYPE3(tt::common_type<const int, const int>::type, int);
BOOST_CHECK_TYPE3(tt::common_type<const int, const long>::type, long);
}
TT_TEST_END