From b61975fa28b67c57b6a703090b42641e96436e1b Mon Sep 17 00:00:00 2001 From: "A. Jiang" Date: Fri, 25 Jul 2025 15:31:21 +0800 Subject: [PATCH 1/2] [libc++][format][NFC] Reimplement and granularize `__fmt_pair_like` `` needs `format_kind` and `range_format` since C++26, but it shouldn't drag in too many other stuffs necessary for `<__format/concepts.h>`. --- libcxx/include/CMakeLists.txt | 1 + libcxx/include/__format/concepts.h | 14 ------ libcxx/include/__format/fmt_pair_like.h | 47 +++++++++++++++++++ .../__format/range_default_formatter.h | 1 + libcxx/include/__format/range_format.h | 2 +- libcxx/include/__format/range_formatter.h | 1 + libcxx/include/module.modulemap.in | 1 + 7 files changed, 52 insertions(+), 15 deletions(-) create mode 100644 libcxx/include/__format/fmt_pair_like.h diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt index ed5475141b50a..51444ec668e2b 100644 --- a/libcxx/include/CMakeLists.txt +++ b/libcxx/include/CMakeLists.txt @@ -381,6 +381,7 @@ set(files __format/enable_insertable.h __format/escaped_output_table.h __format/extended_grapheme_cluster_table.h + __format/fmt_pair_like.h __format/format_arg.h __format/format_arg_store.h __format/format_args.h diff --git a/libcxx/include/__format/concepts.h b/libcxx/include/__format/concepts.h index 28297c612db77..5b603701c0248 100644 --- a/libcxx/include/__format/concepts.h +++ b/libcxx/include/__format/concepts.h @@ -15,12 +15,8 @@ #include <__config> #include <__format/format_parse_context.h> #include <__fwd/format.h> -#include <__fwd/tuple.h> -#include <__tuple/tuple_size.h> -#include <__type_traits/is_specialization.h> #include <__type_traits/remove_const.h> #include <__type_traits/remove_reference.h> -#include <__utility/pair.h> #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) # pragma GCC system_header @@ -65,16 +61,6 @@ concept __formattable = # if _LIBCPP_STD_VER >= 23 template concept formattable = __formattable<_Tp, _CharT>; - -// [tuple.like] defines a tuple-like exposition only concept. This concept is -// not related to that. Therefore it uses a different name for the concept. -// -// TODO FMT Add a test to validate we fail when using that concept after P2165 -// has been implemented. -template -concept __fmt_pair_like = - __is_specialization_v<_Tp, pair> || (__is_specialization_v<_Tp, tuple> && tuple_size_v<_Tp> == 2); - # endif // _LIBCPP_STD_VER >= 23 #endif // _LIBCPP_STD_VER >= 20 diff --git a/libcxx/include/__format/fmt_pair_like.h b/libcxx/include/__format/fmt_pair_like.h new file mode 100644 index 0000000000000..a5cdadf454cf0 --- /dev/null +++ b/libcxx/include/__format/fmt_pair_like.h @@ -0,0 +1,47 @@ +// -*- C++ -*- +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef _LIBCPP___FORMAT_FMT_PAIR_LIKE_H +#define _LIBCPP___FORMAT_FMT_PAIR_LIKE_H + +#include <__config> +#include <__fwd/pair.h> +#include <__fwd/tuple.h> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_BEGIN_NAMESPACE_STD + +#if _LIBCPP_STD_VER >= 23 + +// [tuple.like] defines a tuple-like exposition only concept. This concept is not related to that. Therefore it uses a +// different name for the concept. +// +// TODO FMT Add a test to validate we fail when using that concept after P2165 has been implemented. + +// [format.range.fmtkind]/2.2.1 and [tab:formatter.range.type]: +// "U is either a specialization of pair or a specialization of tuple such that tuple_size_v is 2." +// We use an alternative approach to avoid dragging in many templates. +template +inline constexpr bool __is_fmt_pair_like_v = false; +template +inline constexpr bool __is_fmt_pair_like_v> = true; +template +inline constexpr bool __is_fmt_pair_like_v> = true; + +template +concept __fmt_pair_like = __is_fmt_pair_like_v<_Tp>; + +#endif // _LIBCPP_STD_VER >= 23 + +_LIBCPP_END_NAMESPACE_STD + +#endif // _LIBCPP___FORMAT_FMT_PAIR_LIKE_H diff --git a/libcxx/include/__format/range_default_formatter.h b/libcxx/include/__format/range_default_formatter.h index 2769647ad527e..2d2190657b1af 100644 --- a/libcxx/include/__format/range_default_formatter.h +++ b/libcxx/include/__format/range_default_formatter.h @@ -18,6 +18,7 @@ #include <__chrono/statically_widen.h> #include <__config> #include <__format/concepts.h> +#include <__format/fmt_pair_like.h> #include <__format/formatter.h> #include <__format/range_format.h> #include <__format/range_formatter.h> diff --git a/libcxx/include/__format/range_format.h b/libcxx/include/__format/range_format.h index 139cfd92ee32b..fe43923f9d940 100644 --- a/libcxx/include/__format/range_format.h +++ b/libcxx/include/__format/range_format.h @@ -16,7 +16,7 @@ #include <__concepts/same_as.h> #include <__config> -#include <__format/concepts.h> +#include <__format/fmt_pair_like.h> #include <__ranges/concepts.h> #include <__type_traits/remove_cvref.h> diff --git a/libcxx/include/__format/range_formatter.h b/libcxx/include/__format/range_formatter.h index 0d7fe9970c080..06d2b4cb4b9f4 100644 --- a/libcxx/include/__format/range_formatter.h +++ b/libcxx/include/__format/range_formatter.h @@ -20,6 +20,7 @@ #include <__config> #include <__format/buffer.h> #include <__format/concepts.h> +#include <__format/fmt_pair_like.h> #include <__format/format_context.h> #include <__format/format_error.h> #include <__format/formatter.h> diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in index 117556edb5d20..5857a83b5fe14 100644 --- a/libcxx/include/module.modulemap.in +++ b/libcxx/include/module.modulemap.in @@ -1338,6 +1338,7 @@ module std [system] { module enable_insertable { header "__format/enable_insertable.h" } module escaped_output_table { header "__format/escaped_output_table.h" } module extended_grapheme_cluster_table { header "__format/extended_grapheme_cluster_table.h" } + module fmt_pair_like { header "__format/fmt_pair_like.h" } module format_arg { header "__format/format_arg.h" } module format_arg_store { header "__format/format_arg_store.h" } module format_args { header "__format/format_args.h" } From b0a2167fb926fc2a0b62ed804c2db1d4cb94d3fc Mon Sep 17 00:00:00 2001 From: "A. Jiang" Date: Fri, 25 Jul 2025 16:02:09 +0800 Subject: [PATCH 2/2] Switching `__fmt_pair_like` back to the original implementation --- libcxx/include/__format/fmt_pair_like.h | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/libcxx/include/__format/fmt_pair_like.h b/libcxx/include/__format/fmt_pair_like.h index a5cdadf454cf0..d2f2f54d5ac0b 100644 --- a/libcxx/include/__format/fmt_pair_like.h +++ b/libcxx/include/__format/fmt_pair_like.h @@ -13,6 +13,8 @@ #include <__config> #include <__fwd/pair.h> #include <__fwd/tuple.h> +#include <__tuple/tuple_size.h> +#include <__type_traits/is_specialization.h> #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) # pragma GCC system_header @@ -29,16 +31,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD // [format.range.fmtkind]/2.2.1 and [tab:formatter.range.type]: // "U is either a specialization of pair or a specialization of tuple such that tuple_size_v is 2." -// We use an alternative approach to avoid dragging in many templates. -template -inline constexpr bool __is_fmt_pair_like_v = false; -template -inline constexpr bool __is_fmt_pair_like_v> = true; -template -inline constexpr bool __is_fmt_pair_like_v> = true; - template -concept __fmt_pair_like = __is_fmt_pair_like_v<_Tp>; +concept __fmt_pair_like = + __is_specialization_v<_Tp, pair> || (__is_specialization_v<_Tp, tuple> && tuple_size_v<_Tp> == 2); #endif // _LIBCPP_STD_VER >= 23