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Unify behavior of is_copy_constructible triat when dealing with rvalues + add comments for some tests (refs #8802):

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[SVN r85104]
This commit is contained in:
Antony Polukhin
2013-07-22 12:51:09 +00:00
parent adfe8642af
commit 2429f259cc
2 changed files with 24 additions and 5 deletions
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9
include/boost/type_traits/is_copy_constructible.hpp
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@@ -13,6 +13,7 @@
#include <boost/type_traits/detail/yes_no_type.hpp>
#include <boost/type_traits/is_base_and_derived.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/type_traits/is_rvalue_reference.hpp>
#include <boost/utility/declval.hpp>
#include <boost/noncopyable.hpp>
@@ -67,9 +68,11 @@ struct is_copy_constructible_impl2 {
// ...
// };
BOOST_STATIC_CONSTANT(bool, value = (
sizeof(test(
boost::declval<BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type>()
)) == sizeof(boost::type_traits::yes_type)
sizeof(test(
boost::declval<BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type>()
)) == sizeof(boost::type_traits::yes_type)
||
boost::is_rvalue_reference<T>::value
));
};

20
test/is_copy_constructible_test.cpp
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@@ -259,11 +259,27 @@ BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_copy_constructible<enum_UDT>::value, true
BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int&>::value, true);
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int&&>::value, false);
// Code like `int&& a = 10;` or
// struct nonc {
// nonc() = default;
// nonc(const nonc&) = delete;
// nonc(nonc&&) = delete;
// nonc& operator=(const nonc&) = delete;
// nonc& operator=(nonc&&) = delete;
// };
//
// nonc && a = nonc();
// is legal in C++11. so this trait MUST return true.
BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int&&>::value, true);
#endif
BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_copy_constructible<const int&>::value, true);
// Following three tests may give different results because of copiler and C++03/C++11
// Following three tests may give different results because of compiler and C++03/C++11.
// On C++11 compiler following code:
// int c[2][4][5][6][3];
// int b[2][4][5][6][3] = std::move(c);
// does not compile, so we expect `false` to be the result of those three tests.
BOOST_CHECK_SOFT_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int[2]>::value, false, true);
BOOST_CHECK_SOFT_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int[3][2]>::value, false, true);
BOOST_CHECK_SOFT_INTEGRAL_CONSTANT(::tt::is_copy_constructible<int[2][4][5][6][3]>::value, false, true);