| 1 | // RUN: %clang_cc1 -std=c++17 %s -verify |
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| 2 | // expected-no-diagnostics |
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| 3 | |
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| 4 | // This test attempts to ensure that the below template parameter pack |
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| 5 | // splitting technique executes in linear time in the number of template |
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| 6 | // parameters. The size of the list below is selected so as to execute |
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| 7 | // relatively quickly on a "good" compiler and to time out otherwise. |
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| 8 | |
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| 9 | template<typename...> struct TypeList; |
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| 10 | |
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| 11 | namespace detail { |
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| 12 | template<unsigned> using Unsigned = unsigned; |
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| 13 | template<typename T, T ...N> using ListOfNUnsignedsImpl = TypeList<Unsigned<N>...>; |
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| 14 | template<unsigned N> using ListOfNUnsigneds = |
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| 15 | __make_integer_seq<ListOfNUnsignedsImpl, unsigned, N>; |
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| 16 | |
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| 17 | template<typename T> struct TypeWrapper { |
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| 18 | template<unsigned> using AsTemplate = T; |
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| 19 | }; |
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| 20 | |
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| 21 | template<typename ...N> struct Splitter { |
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| 22 | template<template<N> class ...L, |
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| 23 | template<unsigned> class ...R> struct Split { |
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| 24 | using Left = TypeList<L<0>...>; |
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| 25 | using Right = TypeList<R<0>...>; |
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| 26 | }; |
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| 27 | }; |
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| 28 | } |
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| 29 | |
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| 30 | template<typename TypeList, unsigned N, typename = detail::ListOfNUnsigneds<N>> |
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| 31 | struct SplitAtIndex; |
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| 32 | |
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| 33 | template<typename ...T, unsigned N, typename ...NUnsigneds> |
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| 34 | struct SplitAtIndex<TypeList<T...>, N, TypeList<NUnsigneds...>> : |
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| 35 | detail::Splitter<NUnsigneds...>:: |
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| 36 | template Split<detail::TypeWrapper<T>::template AsTemplate...> {}; |
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| 37 | |
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| 38 | template<typename T, int N> struct Rep : Rep<typename Rep<T, N-1>::type, 1> {}; |
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| 39 | template<typename ...T> struct Rep<TypeList<T...>, 1> { typedef TypeList<T..., T...> type; }; |
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| 40 | |
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| 41 | using Ints = Rep<TypeList<int>, 14>::type; |
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| 42 | |
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| 43 | template<typename T> extern int Size; |
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| 44 | template<typename ...T> constexpr int Size<TypeList<T...>> = sizeof...(T); |
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| 45 | |
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| 46 | using Left = SplitAtIndex<Ints, Size<Ints> / 2>::Left; |
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| 47 | using Right = SplitAtIndex<Ints, Size<Ints> / 2>::Right; |
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| 48 | static_assert(Size<Left> == 8192); |
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| 49 | static_assert(Size<Right> == 8192); |
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| 50 | |
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| 51 | template<typename L, typename R> struct Concat; |
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| 52 | template<typename ...L, typename ...R> struct Concat<TypeList<L...>, TypeList<R...>> { |
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| 53 | using type = TypeList<L..., R...>; |
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| 54 | }; |
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| 55 | |
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| 56 | using Ints = Concat<Left, Right>::type; |
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| 57 | |
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