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Add a converting constructor to result<void>

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This commit is contained in:
Peter Dimov
2023-09-12 04:48:45 +03:00
parent 951b3fe7b4
commit c360ff1b1c
2 changed files with 81 additions and 0 deletions
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17
include/boost/system/result.hpp
View File

@@ -538,6 +538,23 @@ public:
{
}
// converting
template<class E2, class En = typename std::enable_if<
std::is_convertible<E2, E>::value
>::type>
BOOST_CXX14_CONSTEXPR result( result<void, E2> const& r2 )
noexcept(
std::is_nothrow_constructible<E, E2>::value &&
std::is_nothrow_default_constructible<E2>::value &&
std::is_nothrow_copy_constructible<E2>::value )
: v_( in_place_error, r2.error() )
{
if( r2 )
{
this->emplace();
}
}
// queries
constexpr bool has_value() const noexcept

64
test/result_convert_construct.cpp
View File

@@ -183,6 +183,67 @@ int main()
//
{
result<void, int> r;
result<void, X> r2 = r;
BOOST_TEST( r2 );
BOOST_TEST_EQ( X::instances, 0 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<void, int> const r;
result<void, X> r2 = r;
BOOST_TEST( r2 );
BOOST_TEST_EQ( X::instances, 0 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<void, X> r2 = result<void, int>();
BOOST_TEST( r2 );
BOOST_TEST_EQ( X::instances, 0 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<void, int> r( 5 );
result<void, X> r2 = r;
BOOST_TEST( !r2 );
BOOST_TEST_EQ( r2.error(), X(5) );
BOOST_TEST_EQ( X::instances, 1 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<void, int> const r( 6 );
result<void, X> r2 = r;
BOOST_TEST( !r2 );
BOOST_TEST_EQ( r2.error(), X(6) );
BOOST_TEST_EQ( X::instances, 1 );
}
{
result<void, X> r2 = result<void, int>( 7 );
BOOST_TEST( !r2 );
BOOST_TEST_EQ( r2.error(), X(7) );
BOOST_TEST_EQ( X::instances, 1 );
}
BOOST_TEST_EQ( X::instances, 0 );
//
{
int x = 5;
@@ -225,6 +286,9 @@ int main()
BOOST_TEST_TRAIT_FALSE((std::is_constructible<result<int, void*>, result<int, int>>));
BOOST_TEST_TRAIT_FALSE((std::is_convertible<result<int, int>, result<int, void*>>));
BOOST_TEST_TRAIT_FALSE((std::is_constructible<result<void, void*>, result<void, int>>));
BOOST_TEST_TRAIT_FALSE((std::is_convertible<result<void, int>, result<void, void*>>));
BOOST_TEST_TRAIT_TRUE((std::is_constructible<result<int const&>, result<int&>>));
BOOST_TEST_TRAIT_TRUE((std::is_convertible<result<int&>, result<int const&>>));