From 55cf4f843790faa3335ef3e4baf758860a9a107d Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Tue, 19 Sep 2023 14:37:15 +0100 Subject: [PATCH] libstdc++: Define C++23 std::forward_like (P2445R1) libstdc++-v3/ChangeLog: * include/bits/move.h (forward_list): Define for C++23. * include/bits/version.def (forward_like): Define. * include/bits/version.h: Regenerate. * include/std/utility (__glibcxx_want_forward_like): Define. * testsuite/20_util/forward_like/1.cc: New test. * testsuite/20_util/forward_like/2_neg.cc: New test. * testsuite/20_util/forward_like/version.cc: New test. --- libstdc++-v3/include/bits/move.h | 26 ++++++++ libstdc++-v3/include/bits/version.def | 8 +++ libstdc++-v3/include/bits/version.h | 27 ++++++--- libstdc++-v3/include/std/utility | 5 +- .../testsuite/20_util/forward_like/1.cc | 59 +++++++++++++++++++ .../testsuite/20_util/forward_like/2_neg.cc | 10 ++++ .../testsuite/20_util/forward_like/version.cc | 10 ++++ 7 files changed, 135 insertions(+), 10 deletions(-) create mode 100644 libstdc++-v3/testsuite/20_util/forward_like/1.cc create mode 100644 libstdc++-v3/testsuite/20_util/forward_like/2_neg.cc create mode 100644 libstdc++-v3/testsuite/20_util/forward_like/version.cc diff --git a/libstdc++-v3/include/bits/move.h b/libstdc++-v3/include/bits/move.h index 00997d6f1fb6..0151d78aff93 100644 --- a/libstdc++-v3/include/bits/move.h +++ b/libstdc++-v3/include/bits/move.h @@ -89,6 +89,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION return static_cast<_Tp&&>(__t); } +#if __glibcxx_forward_like // C++ >= 23 + template + [[nodiscard]] + constexpr decltype(auto) + forward_like(_Up&& __x) noexcept + { + constexpr bool __as_rval = is_rvalue_reference_v<_Tp&&>; + + if constexpr (is_const_v>) + { + using _Up2 = remove_reference_t<_Up>; + if constexpr (__as_rval) + return static_cast(__x); + else + return static_cast(__x); + } + else + { + if constexpr (__as_rval) + return static_cast&&>(__x); + else + return static_cast<_Up&>(__x); + } + } +#endif + /** * @brief Convert a value to an rvalue. * @param __t A thing of arbitrary type. diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def index 6252f5478e0a..8f008f9048fc 100644 --- a/libstdc++-v3/include/bits/version.def +++ b/libstdc++-v3/include/bits/version.def @@ -1542,6 +1542,14 @@ ftms = { }; }; +ftms = { + name = forward_like; + values = { + v = 202207; + cxxmin = 23; + }; +}; + ftms = { name = ios_noreplace; values = { diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h index 782198acc0c9..b6cb8906b4dc 100644 --- a/libstdc++-v3/include/bits/version.h +++ b/libstdc++-v3/include/bits/version.h @@ -1890,6 +1890,17 @@ #undef __glibcxx_want_formatters // from version.def line 1546 +#if !defined(__cpp_lib_forward_like) +# if (__cplusplus >= 202302L) +# define __glibcxx_forward_like 202207L +# if defined(__glibcxx_want_all) || defined(__glibcxx_want_forward_like) +# define __cpp_lib_forward_like 202207L +# endif +# endif +#endif /* !defined(__cpp_lib_forward_like) && defined(__glibcxx_want_forward_like) */ +#undef __glibcxx_want_forward_like + +// from version.def line 1554 #if !defined(__cpp_lib_ios_noreplace) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED # define __glibcxx_ios_noreplace 202207L @@ -1900,7 +1911,7 @@ #endif /* !defined(__cpp_lib_ios_noreplace) && defined(__glibcxx_want_ios_noreplace) */ #undef __glibcxx_want_ios_noreplace -// from version.def line 1555 +// from version.def line 1563 #if !defined(__cpp_lib_move_only_function) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED # define __glibcxx_move_only_function 202110L @@ -1911,7 +1922,7 @@ #endif /* !defined(__cpp_lib_move_only_function) && defined(__glibcxx_want_move_only_function) */ #undef __glibcxx_want_move_only_function -// from version.def line 1564 +// from version.def line 1572 #if !defined(__cpp_lib_spanstream) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED && (__glibcxx_span) # define __glibcxx_spanstream 202106L @@ -1922,7 +1933,7 @@ #endif /* !defined(__cpp_lib_spanstream) && defined(__glibcxx_want_spanstream) */ #undef __glibcxx_want_spanstream -// from version.def line 1574 +// from version.def line 1582 #if !defined(__cpp_lib_stacktrace) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_HAVE_STACKTRACE) # define __glibcxx_stacktrace 202011L @@ -1933,7 +1944,7 @@ #endif /* !defined(__cpp_lib_stacktrace) && defined(__glibcxx_want_stacktrace) */ #undef __glibcxx_want_stacktrace -// from version.def line 1584 +// from version.def line 1592 #if !defined(__cpp_lib_string_contains) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED # define __glibcxx_string_contains 202011L @@ -1944,7 +1955,7 @@ #endif /* !defined(__cpp_lib_string_contains) && defined(__glibcxx_want_string_contains) */ #undef __glibcxx_want_string_contains -// from version.def line 1593 +// from version.def line 1601 #if !defined(__cpp_lib_string_resize_and_overwrite) # if (__cplusplus >= 202302L) && _GLIBCXX_HOSTED # define __glibcxx_string_resize_and_overwrite 202110L @@ -1955,7 +1966,7 @@ #endif /* !defined(__cpp_lib_string_resize_and_overwrite) && defined(__glibcxx_want_string_resize_and_overwrite) */ #undef __glibcxx_want_string_resize_and_overwrite -// from version.def line 1602 +// from version.def line 1610 #if !defined(__cpp_lib_fstream_native_handle) # if (__cplusplus > 202302L) && _GLIBCXX_HOSTED # define __glibcxx_fstream_native_handle 202306L @@ -1966,7 +1977,7 @@ #endif /* !defined(__cpp_lib_fstream_native_handle) && defined(__glibcxx_want_fstream_native_handle) */ #undef __glibcxx_want_fstream_native_handle -// from version.def line 1611 +// from version.def line 1619 #if !defined(__cpp_lib_ratio) # if (__cplusplus > 202302L) # define __glibcxx_ratio 202306L @@ -1977,7 +1988,7 @@ #endif /* !defined(__cpp_lib_ratio) && defined(__glibcxx_want_ratio) */ #undef __glibcxx_want_ratio -// from version.def line 1619 +// from version.def line 1627 #if !defined(__cpp_lib_to_string) # if (__cplusplus > 202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars) # define __glibcxx_to_string 202306L diff --git a/libstdc++-v3/include/std/utility b/libstdc++-v3/include/std/utility index f30e802a88db..bdaf5d4c31b9 100644 --- a/libstdc++-v3/include/std/utility +++ b/libstdc++-v3/include/std/utility @@ -68,9 +68,10 @@ #include #include -#define __glibcxx_want_exchange_function -#define __glibcxx_want_constexpr_algorithms #define __glibcxx_want_as_const +#define __glibcxx_want_constexpr_algorithms +#define __glibcxx_want_exchange_function +#define __glibcxx_want_forward_like #define __glibcxx_want_integer_comparison_functions #define __glibcxx_want_to_underlying #define __glibcxx_want_unreachable diff --git a/libstdc++-v3/testsuite/20_util/forward_like/1.cc b/libstdc++-v3/testsuite/20_util/forward_like/1.cc new file mode 100644 index 000000000000..928e60094a32 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/forward_like/1.cc @@ -0,0 +1,59 @@ +// { dg-do compile { target c++23 } } +// { dg-add-options no_pch } + +#include + +#ifndef __cpp_lib_forward_like +# error "Feature-test macro for forward_like missing in " +#elif __cpp_lib_forward_like != 202207L +# error "Feature-test macro for forward_like has wrong value in " +#endif + +template +using forward_like_t = decltype(std::forward_like(std::declval())); + +#if 0 +using std::is_same_v; +#else +#include +template concept is_same_v = std::same_as; +#endif + +static_assert( is_same_v, long&&> ); +static_assert( is_same_v, long&> ); +static_assert( is_same_v, long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, const long&&> ); +static_assert( is_same_v, const long&> ); +static_assert( is_same_v, const long&&> ); + +static_assert( is_same_v, long&&> ); +static_assert( is_same_v, long&> ); +static_assert( is_same_v, long&&> ); + +static_assert( is_same_v, + const volatile long&&> ); +static_assert( is_same_v, + const volatile long&> ); +static_assert( is_same_v, + const volatile long&&> ); diff --git a/libstdc++-v3/testsuite/20_util/forward_like/2_neg.cc b/libstdc++-v3/testsuite/20_util/forward_like/2_neg.cc new file mode 100644 index 000000000000..ff835af19151 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/forward_like/2_neg.cc @@ -0,0 +1,10 @@ +// { dg-do compile { target c++23 } } + +#include + +auto x1 = std::forward_like(1); // { dg-error "here" } +// { dg-error "forming reference to void" "" { target *-*-* } 0 } +auto x2 = std::forward_like(1); // { dg-error "here" } +// { dg-error "forming reference to qualified function" "" { target *-*-* } 0 } + +// { dg-prune-output "inconsistent deduction for auto return type" } // PR111484 diff --git a/libstdc++-v3/testsuite/20_util/forward_like/version.cc b/libstdc++-v3/testsuite/20_util/forward_like/version.cc new file mode 100644 index 000000000000..058dccfabe21 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/forward_like/version.cc @@ -0,0 +1,10 @@ +// { dg-do preprocess { target c++23 } } +// { dg-add-options no_pch } + +#include + +#ifndef __cpp_lib_forward_like +# error "Feature-test macro for forward_like missing in " +#elif __cpp_lib_forward_like != 202207L +# error "Feature-test macro for forward_like has wrong value in " +#endif -- 2.47.2