From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id DE3FA3858D28; Tue, 24 Jan 2023 23:51:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DE3FA3858D28 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1674604295; bh=N7Y1fgMb/6a44G2ytwplPWBMdacNpA4BupjX0u174Mo=; h=From:To:Subject:Date:From; b=ls2bl7KhPkZn+qncy/7+XVF+vrecxIiRZPMzpjg7pG1eHHUHFCgn1xnwPgvusqWQB x39ezAQWeoQ5VOsmXxn0yFMTeAghnrM420CQ5btBDyKI8+yY1M8n1UNYvgzASzP2fM ZLg25T8855R/J6EgBZOmLobaDEcBIk8mxeeShTNY= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jonathan Wakely To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-5338] libstdc++: Include std::ranges::subrange definition in [PR102301] X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: aba6416e95ab4138a0ecab0fd51e7e9329d74a45 X-Git-Newrev: 33ed11085837e9492c6ed512931f5b6375c68ee7 Message-Id: <20230124235135.DE3FA3858D28@sourceware.org> Date: Tue, 24 Jan 2023 23:51:35 +0000 (GMT) List-Id: https://gcc.gnu.org/g:33ed11085837e9492c6ed512931f5b6375c68ee7 commit r13-5338-g33ed11085837e9492c6ed512931f5b6375c68ee7 Author: Jonathan Wakely Date: Mon Jan 23 12:25:36 2023 +0000 libstdc++: Include std::ranges::subrange definition in [PR102301] In order for std::make_from_tuple to work with tuple-like types, the overloads of std::get for those types must have been declared before the definition of std::make_from_tuple. That means we need to include the definition of std::ranges::subrange in . The definitions of std::pair and its overloads of std::get are already included in . We provide forward declarations of std::array and its std::get overloads in . We could just declare subrange without defining it, and give ranges::get a non-deduced return type, like so: namespace ranges { enum class subrange_kind : bool { unsized, sized}; template S, subrange_kind K> requires (K == subrange_kind::sized || !sized_sentinel_for) class subrange; template requires (_Num < 2) constexpr __conditional_t<_Num == 0, _It, _Sent> get(const subrange<_It, _Sent, _Kind>& __r); template requires (_Num < 2) constexpr __conditional_t<_Num == 0, _It, _Sent> get(subrange<_It, _Sent, _Kind>&& __r) } using ranges::get; It is a bit late in the GCC 13 dev cycle to do this, so just include the right headers for now. Also add the dangling check to std::make_from_tuple added by P2255. libstdc++-v3/ChangeLog: PR libstdc++/102301 * include/bits/ranges_base.h: Include for std::make_reverse_iterator. * include/std/tuple: Include for subrange. (make_from_tuple): Add static assertion from P2255 to diagnose dangling references. * testsuite/20_util/tuple/make_from_tuple/dangling_ref.cc: New test. * testsuite/20_util/tuple/make_from_tuple/tuple_like.cc: New test. Diff: --- libstdc++-v3/include/bits/ranges_base.h | 2 +- libstdc++-v3/include/std/tuple | 16 ++++++-- .../20_util/tuple/make_from_tuple/dangling_ref.cc | 5 +++ .../20_util/tuple/make_from_tuple/tuple_like.cc | 43 ++++++++++++++++++++++ 4 files changed, 61 insertions(+), 5 deletions(-) diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index 26b3a983f72..86952b34096 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -34,7 +34,7 @@ #if __cplusplus > 201703L #include -#include +#include #include #include diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple index 3d82ed1c370..c773b3a348b 100644 --- a/libstdc++-v3/include/std/tuple +++ b/libstdc++-v3/include/std/tuple @@ -37,10 +37,11 @@ #include // for std::pair #include // for std::allocator_arg_t -#include // for std::get, std::tuple_size etc. +#include // for std::tuple_size etc. #include // for std::__invoke #if __cplusplus > 201703L # include +# include // for std::ranges::subrange # define __cpp_lib_constexpr_tuple 201811L #endif @@ -2312,9 +2313,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION make_from_tuple(_Tuple&& __t) noexcept(__unpack_std_tuple) { - return __make_from_tuple_impl<_Tp>( - std::forward<_Tuple>(__t), - make_index_sequence>>{}); + constexpr size_t __n = tuple_size_v>; +#if __has_builtin(__reference_constructs_from_temporary) + if constexpr (__n == 1) + { + using _Elt = decltype(std::get<0>(std::declval<_Tuple>())); + static_assert(!__reference_constructs_from_temporary(_Tp, _Elt)); + } +#endif + return __make_from_tuple_impl<_Tp>(std::forward<_Tuple>(__t), + make_index_sequence<__n>{}); } #endif // C++17 diff --git a/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/dangling_ref.cc b/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/dangling_ref.cc new file mode 100644 index 00000000000..7958ec888a3 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/dangling_ref.cc @@ -0,0 +1,5 @@ +// { dg-do compile { target c++17 } } +#include +std::tuple f(); +auto t = std::make_from_tuple(f()); // { dg-error "here" } +// { dg-error "static assertion failed" "" { target *-*-* } 0 } diff --git a/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/tuple_like.cc b/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/tuple_like.cc new file mode 100644 index 00000000000..de694554d86 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/tuple/make_from_tuple/tuple_like.cc @@ -0,0 +1,43 @@ +// { dg-do compile { target c++17 } } + +#include +#include + +struct Two +{ + Two(const char*, int); +}; + +void +test_pair() +{ + auto two = std::make_from_tuple(std::pair("one", 2)); + static_assert(std::is_same_v, "make from pair"); +} + +#include + +struct Three +{ + Three(int, int, int); +}; + +void +test_array() +{ + Three three = std::make_from_tuple(std::array{{1, 2, 3}}); + static_assert(std::is_same_v, "make from array"); +} + +#if __cplusplus >= 202002L +#include +#include + +void +test_subrange() // PR libstdc++/102301 +{ + auto r = std::views::iota(0, 5); + auto v = std::make_from_tuple>(std::ranges::subrange(r)); + static_assert(std::is_same_v>, "from subrange"); +} +#endif