2016-10-13 Jonathan Wakely <jwakely@redhat.com>
+ * include/std/functional (_Not_fn): Make exception specifications
+ depend on whether negating the result can throw.
+ * testsuite/20_util/not_fn/1.cc: Move to ...
+ * testsuite/20_util/function_objects/not_fn/1.cc: ... here. Add tests
+ for types that can throw when negated and that cannot be negated.
+
* include/bits/invoke.h (__invoke): Fix exception-specification.
* include/std/functional (invoke): Likewise.
* testsuite/20_util/function_objects/invoke/1.cc: New test.
template<typename _Fn>
class _Not_fn
{
+ template<typename _Tp>
+ using __is_nothrow_negatable
+ = __bool_constant<noexcept(!std::declval<_Tp>())>;
+
+ template<typename _Fn2, typename... _Args>
+ using __noexcept_cond = __and_<
+ __is_nothrow_callable<_Fn2(_Args&&...)>,
+ __is_nothrow_negatable<result_of_t<_Fn2(_Args&&...)>>
+ >;
+
public:
template<typename _Fn2>
_Not_fn(_Fn2&& __fn, int)
template<typename... _Args>
auto
operator()(_Args&&... __args) &
- noexcept(__is_nothrow_callable<_Fn&(_Args&&...)>::value)
+ noexcept(__noexcept_cond<_Fn&, _Args&&...>::value)
-> decltype(!std::declval<result_of_t<_Fn&(_Args&&...)>>())
{ return !std::__invoke(_M_fn, std::forward<_Args>(__args)...); }
template<typename... _Args>
auto
operator()(_Args&&... __args) const &
- noexcept(__is_nothrow_callable<const _Fn&(_Args&&...)>::value)
+ noexcept(__noexcept_cond<const _Fn&, _Args&&...>::value)
-> decltype(!std::declval<result_of_t<const _Fn&(_Args&&...)>>())
{ return !std::__invoke(_M_fn, std::forward<_Args>(__args)...); }
template<typename... _Args>
auto
operator()(_Args&&... __args) &&
- noexcept(__is_nothrow_callable<_Fn&&(_Args&&...)>::value)
+ noexcept(__noexcept_cond<_Fn&&, _Args&&...>::value)
-> decltype(!std::declval<result_of_t<_Fn&&(_Args&&...)>>())
{
return !std::__invoke(std::move(_M_fn),
template<typename... _Args>
auto
operator()(_Args&&... __args) const &&
- noexcept(__is_nothrow_callable<const _Fn&&(_Args&&...)>::value)
+ noexcept(__noexcept_cond<const _Fn&&, _Args&&...>::value)
-> decltype(!std::declval<result_of_t<const _Fn&&(_Args&&...)>>())
{
return !std::__invoke(std::move(_M_fn),
auto copy(nf); // PR libstdc++/70564
}
+void
+test06()
+{
+ struct Boolean {
+ Boolean operator!() noexcept(false) { return *this; }
+ };
+ struct F {
+ Boolean operator()() { return {}; }
+ };
+ F f;
+ auto notf = std::not_fn(f);
+ using NotF = decltype(notf);
+ static_assert( std::is_callable<NotF()>::value, "cannot negate" );
+ static_assert( !noexcept(notf()), "conversion to bool affects noexcept" );
+}
+
+void
+test07()
+{
+ struct NonNegatable { };
+ struct F {
+ NonNegatable operator()() { return {}; }
+ };
+ F f;
+ auto notf = std::not_fn(f);
+ using NotF = decltype(notf);
+ static_assert( !std::is_callable<NotF()>::value, "cannot negate" );
+}
+
int
main()
{
test03();
test04();
test05();
+ test06();
+ test07();
}