[libcxx] Delay evaluation of __make_tuple_types to prevent blowing the max template instantiation depth. Fixes Bug #18345 Summary: http://llvm.org/bugs/show_bug.cgi?id=18345 Tuple's constructor and assignment operators for "tuple-like" types evaluates __make_tuple_types unnecessarily. In the case of a large array this can blow the template instantiation depth. Ex: ``` #include <array> #include <tuple> #include <memory> typedef std::array<int, 1256> array_t; typedef std::tuple<array_t> tuple_t; int main() { array_t a; tuple_t t(a); // broken t = a; // broken // make_shared uses tuple behind the scenes. This bug breaks this code. std::make_shared<array_t>(a); } ``` To prevent this from happening we delay the instantiation of `__make_tuple_types` until after we perform the length check. Currently `__make_tuple_types` is instantiated at the same time that the length check . Test Plan: Two tests have been added. One for the "tuple-like" constructors and another for the "tuple-like" assignment operator. Reviewers: mclow.lists, EricWF Reviewed By: EricWF Subscribers: K-ballo, cfe-commits Differential Revision: http://reviews.llvm.org/D4467 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@220769 91177308-0d34-0410-b5e6-96231b3b80d8 diff --git a/include/__tuple b/include/__tuple index ee5b916..bffb95c 100644 --- a/include/__tuple +++ b/include/__tuple
@@ -245,19 +245,30 @@ // __tuple_convertible -template <bool, class _Tp, class _Up> +template <class, class> struct __tuple_convertible_imp : public false_type {}; template <class _Tp0, class ..._Tp, class _Up0, class ..._Up> -struct __tuple_convertible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > +struct __tuple_convertible_imp<__tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > : public integral_constant<bool, is_convertible<_Tp0, _Up0>::value && - __tuple_convertible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; + __tuple_convertible_imp<__tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; template <> -struct __tuple_convertible_imp<true, __tuple_types<>, __tuple_types<> > +struct __tuple_convertible_imp<__tuple_types<>, __tuple_types<> > : public true_type {}; +template <bool, class, class> +struct __tuple_convertible_apply : public false_type {}; + +template <class _Tp, class _Up> +struct __tuple_convertible_apply<true, _Tp, _Up> + : public __tuple_convertible_imp< + typename __make_tuple_types<_Tp>::type + , typename __make_tuple_types<_Up>::type + > +{}; + template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value, bool = __tuple_like<_Up>::value> struct __tuple_convertible @@ -265,26 +276,36 @@ template <class _Tp, class _Up> struct __tuple_convertible<_Tp, _Up, true, true> - : public __tuple_convertible_imp<tuple_size<typename remove_reference<_Tp>::type>::value == - tuple_size<_Up>::value, - typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type> + : public __tuple_convertible_apply<tuple_size<typename remove_reference<_Tp>::type>::value == + tuple_size<_Up>::value, _Tp, _Up> {}; // __tuple_constructible -template <bool, class _Tp, class _Up> +template <class, class> struct __tuple_constructible_imp : public false_type {}; template <class _Tp0, class ..._Tp, class _Up0, class ..._Up> -struct __tuple_constructible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > +struct __tuple_constructible_imp<__tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > : public integral_constant<bool, is_constructible<_Up0, _Tp0>::value && - __tuple_constructible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; + __tuple_constructible_imp<__tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; template <> -struct __tuple_constructible_imp<true, __tuple_types<>, __tuple_types<> > +struct __tuple_constructible_imp<__tuple_types<>, __tuple_types<> > : public true_type {}; +template <bool _SameSize, class, class> +struct __tuple_constructible_apply : public false_type {}; + +template <class _Tp, class _Up> +struct __tuple_constructible_apply<true, _Tp, _Up> + : public __tuple_constructible_imp< + typename __make_tuple_types<_Tp>::type + , typename __make_tuple_types<_Up>::type + > +{}; + template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value, bool = __tuple_like<_Up>::value> struct __tuple_constructible @@ -292,26 +313,36 @@ template <class _Tp, class _Up> struct __tuple_constructible<_Tp, _Up, true, true> - : public __tuple_constructible_imp<tuple_size<typename remove_reference<_Tp>::type>::value == - tuple_size<_Up>::value, - typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type> + : public __tuple_constructible_apply<tuple_size<typename remove_reference<_Tp>::type>::value == + tuple_size<_Up>::value, _Tp, _Up> {}; // __tuple_assignable -template <bool, class _Tp, class _Up> +template <class, class> struct __tuple_assignable_imp : public false_type {}; template <class _Tp0, class ..._Tp, class _Up0, class ..._Up> -struct __tuple_assignable_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > +struct __tuple_assignable_imp<__tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> > : public integral_constant<bool, is_assignable<_Up0&, _Tp0>::value && - __tuple_assignable_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; + __tuple_assignable_imp<__tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {}; template <> -struct __tuple_assignable_imp<true, __tuple_types<>, __tuple_types<> > +struct __tuple_assignable_imp<__tuple_types<>, __tuple_types<> > : public true_type {}; +template <bool, class, class> +struct __tuple_assignable_apply : public false_type {}; + +template <class _Tp, class _Up> +struct __tuple_assignable_apply<true, _Tp, _Up> + : __tuple_assignable_imp< + typename __make_tuple_types<_Tp>::type + , typename __make_tuple_types<_Up>::type + > +{}; + template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value, bool = __tuple_like<_Up>::value> struct __tuple_assignable @@ -319,9 +350,8 @@ template <class _Tp, class _Up> struct __tuple_assignable<_Tp, _Up, true, true> - : public __tuple_assignable_imp<tuple_size<typename remove_reference<_Tp>::type>::value == - tuple_size<_Up>::value, - typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type> + : public __tuple_assignable_apply<tuple_size<typename remove_reference<_Tp>::type>::value == + tuple_size<_Up>::value, _Tp, _Up> {}; _LIBCPP_END_NAMESPACE_STD 