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Define protect(f)::result_type only when F::result_type is defined

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This commit is contained in:
Peter Dimov
2020-06-30 21:58:58 +03:00
parent 1aac698358
commit 9ce9a7ce99
2 changed files with 35 additions and 3 deletions
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18
include/boost/bind/protect.hpp
View File

@ -24,7 +24,21 @@ namespace _bi
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_NO_CXX11_DECLTYPE)
template<class F> class protected_bind_t
template<class T> struct protect_make_void
{
typedef void type;
};
template<class F, class E = void> struct protect_result_type
{
};
template<class F> struct protect_result_type< F, typename protect_make_void<typename F::result_type>::type >
{
typedef typename F::result_type result_type;
};
template<class F> class protected_bind_t: public protect_result_type<F>
{
private:
@ -32,8 +46,6 @@ private:
public:
typedef typename F::result_type result_type;
explicit protected_bind_t( F f ): f_( f )
{
}

20
test/protect_test2.cpp
View File

@ -18,9 +18,29 @@ struct X
struct result_type {};
};
struct Y
{
};
template<class T, class U> struct inherit: T, U
{
};
template<class F> void test2( F )
{
// test that F doesn't have ::result_type
BOOST_TEST_TRAIT_TRUE((boost::core::is_same<typename inherit<F, X>::result_type, typename X::result_type>));
}
int main()
{
test<X>( boost::protect( X() ) );
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_NO_CXX11_DECLTYPE)
test2( boost::protect( Y() ) );
#endif
return boost::report_errors();
}