Author: ericwf Date: Wed Aug 10 17:45:26 2016 New Revision: 278300 URL: http://llvm.org/viewvc/llvm-project?rev=278300&view=rev Log: Implement LWG 2148: Make non-enum default hash specialization well-formed
Summary: This patch removes the static_assert for non-enum types in the primary hash template. Instead non-enum types create a hash<T> specialization that is not constructible nor callable. See also: * http://cplusplus.github.io/LWG/lwg-active.html#2543 * https://llvm.org/bugs/show_bug.cgi?id=28917 Reviewers: mclow.lists, EricWF Subscribers: mehdi_amini, cfe-commits Differential Revision: https://reviews.llvm.org/D23331 Added: libcxx/trunk/test/std/utilities/function.objects/unord.hash/non_enum.pass.cpp Modified: libcxx/trunk/include/functional libcxx/trunk/test/std/utilities/function.objects/unord.hash/enum.pass.cpp Modified: libcxx/trunk/include/functional URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/functional?rev=278300&r1=278299&r2=278300&view=diff ============================================================================== --- libcxx/trunk/include/functional (original) +++ libcxx/trunk/include/functional Wed Aug 10 17:45:26 2016 @@ -2574,12 +2574,11 @@ struct _LIBCPP_TYPE_VIS_ONLY hash<long d }; #if _LIBCPP_STD_VER > 11 -template <class _Tp> -struct _LIBCPP_TYPE_VIS_ONLY hash + +template <class _Tp, bool = is_enum<_Tp>::value> +struct _LIBCPP_TYPE_VIS_ONLY __enum_hash : public unary_function<_Tp, size_t> { - static_assert(is_enum<_Tp>::value, "This hash only works for enumeration types"); - _LIBCPP_INLINE_VISIBILITY size_t operator()(_Tp __v) const _NOEXCEPT { @@ -2587,6 +2586,17 @@ struct _LIBCPP_TYPE_VIS_ONLY hash return hash<type>{}(static_cast<type>(__v)); } }; +template <class _Tp> +struct _LIBCPP_TYPE_VIS_ONLY __enum_hash<_Tp, false> { + __enum_hash() = delete; + __enum_hash(__enum_hash const&) = delete; + __enum_hash& operator=(__enum_hash const&) = delete; +}; + +template <class _Tp> +struct _LIBCPP_TYPE_VIS_ONLY hash : public __enum_hash<_Tp> +{ +}; #endif Modified: libcxx/trunk/test/std/utilities/function.objects/unord.hash/enum.pass.cpp URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/function.objects/unord.hash/enum.pass.cpp?rev=278300&r1=278299&r2=278300&view=diff ============================================================================== --- libcxx/trunk/test/std/utilities/function.objects/unord.hash/enum.pass.cpp (original) +++ libcxx/trunk/test/std/utilities/function.objects/unord.hash/enum.pass.cpp Wed Aug 10 17:45:26 2016 @@ -7,6 +7,8 @@ // //===----------------------------------------------------------------------===// +// UNSUPPORTED: c++98, c++03, c++11 + // <functional> // make sure that we can hash enumeration values @@ -14,8 +16,6 @@ #include "test_macros.h" -#if TEST_STD_VER >= 14 - #include <functional> #include <cassert> #include <type_traits> @@ -59,6 +59,3 @@ int main() test<Fruits>(); } -#else -int main () {} -#endif Added: libcxx/trunk/test/std/utilities/function.objects/unord.hash/non_enum.pass.cpp URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/function.objects/unord.hash/non_enum.pass.cpp?rev=278300&view=auto ============================================================================== --- libcxx/trunk/test/std/utilities/function.objects/unord.hash/non_enum.pass.cpp (added) +++ libcxx/trunk/test/std/utilities/function.objects/unord.hash/non_enum.pass.cpp Wed Aug 10 17:45:26 2016 @@ -0,0 +1,38 @@ +//===----------------------------------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +// UNSUPPORTED: c++98, c++03, c++11 + +// <functional> + +// Hashing a struct w/o a defined hash should *not* fail, but it should +// create a type that is not constructible and not callable. +// See also: http://cplusplus.github.io/LWG/lwg-active.html#2543 + +#include <functional> +#include <cassert> +#include <type_traits> + +#include "test_macros.h" + +struct X {}; + +int main() +{ + using H = std::hash<X>; + static_assert(!std::is_default_constructible<H>::value, ""); + static_assert(!std::is_copy_constructible<H>::value, ""); + static_assert(!std::is_move_constructible<H>::value, ""); + static_assert(!std::is_copy_assignable<H>::value, ""); + static_assert(!std::is_move_assignable<H>::value, ""); +#if TEST_STD_VER > 14 + static_assert(!std::is_callable<H(X&)>::value, ""); + static_assert(!std::is_callable<H(X const&)>::value, ""); +#endif +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
