--- /dev/null
+// PR c++/66067
+// { dg-do compile { target c++11 } }
+
+namespace std
+{
+ typedef int size_t;
+ template < typename _Tp, _Tp > struct integral_constant
+ {
+ static constexpr _Tp value = 0;
+ typedef integral_constant type;
+ };
+ typedef integral_constant < int, 0 > true_type;
+ typedef integral_constant < int, 0 > false_type;
+ template < typename _Tp > struct enable_if
+ {
+ typedef _Tp type;
+ };
+}
+namespace meta
+{
+ inline namespace v1
+ {
+ template < template < typename ... >class, typename ... >struct defer;
+ template < typename T > T * _nullptr_v ( );
+ template < int N > using size_t = std::integral_constant < int, N >;
+ template < int B > using bool_ = std::integral_constant < int, B >;
+ template < typename T > using dec =
+ std::integral_constant < decltype ( T::value ), 0 >;
+ template < typename T > using eval = typename T::type;
+ template < typename F, typename ... Args > using apply =
+ typename F::template apply < Args ... >;
+ namespace detail
+ {
+ template < typename > struct has_type_;
+ }
+ template < typename T > using has_type = eval < detail::has_type_ < T >>;
+ template < typename T > struct id
+ {
+ using type = T;
+ };
+ template < template < typename ... >class > struct quote;
+ template < typename > struct Trans_NS_extension_apply_list;
+ template < typename, typename List > using apply_list =
+ eval < Trans_NS_extension_apply_list < List >>;
+ namespace detail
+ {
+ template < typename ... >struct _if_;
+ template < typename If, typename Then > struct _if_ <If,
+ Then >:std::enable_if < Then >
+ {
+ };
+ }
+ template < typename ... Args > using if_ =
+ eval < detail::_if_ < Args ... >>;
+ template < int If, typename ... Args > using if_c =
+ eval < detail::_if_ < bool_ < If >, Args ... >>;
+ namespace detail
+ {
+ template < typename ... >struct _and_:std::true_type
+ {
+ };
+ template < typename ... >struct _or_:std::false_type
+ {
+ };
+ }
+ template < int >using not_c = bool_ < 0 >;
+ template < typename Bool > using not_ = not_c < Bool::value >;
+ template < typename ... >using and_ = eval < detail::_and_ <>>;
+ template < typename > using or_ = eval < detail::_or_ <>>;
+ namespace lazy
+ {
+ template < typename ... Bools > using and_ = defer < and_, Bools ... >;
+ }
+ template < typename ... Ts > struct list
+ {
+ static constexpr std::size_t size ( )
+ {
+ return sizeof ... ( Ts );
+ }
+ };
+ template < typename List > using size = size_t < List::size ( ) >;
+ namespace detail
+ {
+ template < typename > struct concat_;
+ }
+ template < typename ... Lists > using concat =
+ eval < detail::concat_ < Lists ... >>;
+ template < typename ListOfLists > using join =
+ apply_list < quote < concat >, ListOfLists >;
+ namespace detail
+ {
+ template < int >struct repeat_n_c_
+ {
+ using type = list <>;
+ };
+ }
+ template < typename > using repeat_n = eval < detail::repeat_n_c_ < 0 >>;
+ template < std::size_t N > using repeat_n_c =
+ eval < detail::repeat_n_c_ < N >>;
+ namespace detail
+ {
+ template < typename > struct at_impl_
+ {
+ template < typename T > static T eval ( T * );
+ };
+ template < typename, typename > struct at_;
+ template < typename ... Ts, typename N > struct at_ <list < Ts ... >,
+ N >:decltype ( at_impl_ < repeat_n <
+ N >>::eval ( _nullptr_v < id < Ts >> ( )... ) )
+ {
+ };
+ }
+ template < typename List, typename N > using at =
+ eval < detail::at_ < List, N >>;
+ template < typename List, std::size_t > using at_c =
+ at < List, size_t < 0 >>;
+ namespace detail
+ {
+ template < typename > struct back_;
+ template < typename Head,
+ typename ... List > struct back_ <list < Head, List ... >>
+ {
+ using type = at_c < list < Head >, sizeof ... ( List ) >;
+ };
+ }
+ template < typename List > using back = eval < detail::back_ < List >>;
+ namespace detail
+ {
+ template < typename, typename > struct push_front_;
+ template < typename ... List,
+ typename T > struct push_front_ <list < List ... >, T >
+ {
+ using type = list < T >;
+ };
+ }
+ template < typename List, typename T > using push_front =
+ eval < detail::push_front_ < List, T >>;
+ namespace detail
+ {
+ template < typename > struct push_back_;
+ }
+ template < typename, typename T > using push_back =
+ eval < detail::push_back_ < T >>;
+ namespace detail
+ {
+ template < typename > struct transform_;
+ }
+ template < typename ... Args > using transform =
+ eval < detail::transform_ < Args ... >>;
+ namespace detail
+ {
+ template < typename > struct is_valid_;
+ template < typename As, typename Ts > using substitutions_ =
+ push_back < join < transform < concat < repeat_n_c < size < Ts >
+ {
+ }
+ >>>>, list < back < As >>>;
+ template < typename Ts > using substitutions =
+ apply < if_c < size < Ts >
+ {
+ }
+ , quote < substitutions_ >>>;
+ template < typename > struct is_vararg_:std::false_type
+ {
+ };
+ template < typename Tags > using is_variadic_ =
+ is_vararg_ < at < push_front < Tags, void >, dec < size < Tags >>>>;
+ template < typename Tags, int =
+ is_variadic_ < Tags >::value > struct lambda_;
+ template < typename ... As > struct lambda_ <list < As ... >, false >
+ {
+ using Tags = list < As ... >;
+ using F = back < Tags >;
+ template < typename, typename > struct impl;
+ template < typename, typename > struct subst_;
+ template < template < typename ... >class C, typename ... Ts,
+ typename Args > struct subst_ <defer < C, Ts ... >, Args >
+ {
+ using type = C < eval < impl < Ts, Args >> ... >;
+ };
+ template < template < typename ... >class C, typename ... Ts,
+ typename Args > struct impl <defer < C, Ts ... >,
+ Args >:subst_ < defer < C >, Args >
+ {
+ };
+ template < typename ... Ts > using apply =
+ eval < if_c < sizeof ... ( Ts ), impl < F, list <>>>>;
+ };
+ }
+ template < typename ... Ts > using lambda =
+ if_c < sizeof ... ( Ts ), detail::lambda_ < list < Ts ... >>>;
+ template < typename T > using is_valid = detail::is_valid_ < T >;
+ namespace detail
+ {
+ template < typename ... >struct let_;
+ template < typename Fn > struct let_ <Fn >
+ {
+ using type = apply < lambda < Fn >>;
+ };
+ }
+ template < typename ... As > using let = eval < detail::let_ < As ... >>;
+ template < typename > struct common_reference_base;
+ template < typename ... >struct common_reference;
+ namespace detail
+ {
+ template < typename > struct builtin_common_impl;
+ template < typename U > using builtin_common_t =
+ meta::apply < builtin_common_impl < U >>;
+ template < typename, typename > using lazy_builtin_common_t =
+ meta::defer < builtin_common_t >;
+ template < typename > struct transform_reference;
+ template < typename, typename U > using common_reference_base_ =
+ common_reference_base < meta::eval < transform_reference < U >>>;
+ }
+ template < typename T, typename U > struct common_reference <T,
+ U >:meta::if_ < meta::let < meta::lazy::and_ < meta::is_valid <
+ detail::lazy_builtin_common_t < T, U >>,
+ meta::or_ < meta::not_ < meta::has_type <
+ detail::common_reference_base_ < T, U >>>>>>,
+ detail::lazy_builtin_common_t < T, U >,
+ detail::common_reference_base_ < T, U >>
+ {
+ };
+ }
+}