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frederick-vs-ja merged 5 commits into from
Apr 12, 2026
Merged

[libc++][format] P3953R3: Rename std::runtime_format #189657

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f6b189b
[libc++][format] P3953R3: Rename std::runtime_format
H-G-Hristov Mar 31, 2026
6789534
Renamed test files
H-G-Hristov Mar 31, 2026
45add62
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H-G-Hristov Mar 31, 2026
619323c
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H-G-Hristov Apr 11, 2026
d0aed8a
Merge branch 'main' into hgh/libcxx/P3953-R1-Rename-std__runtime_format
frederick-vs-ja Apr 12, 2026
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1 change: 1 addition & 0 deletions libcxx/docs/ReleaseNotes/23.rst
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Expand Up @@ -40,6 +40,7 @@ Implemented Papers

- P2440R1: ``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right`` (`Github <https://llvm.org/PR105184>`__)
- P3936R1: Safer ``atomic_ref::address`` (`Github <https://llvm.org/PR189594>`__)
- P3953R3: Rename ``std::runtime_format`` (`Github <https://llvm.org/PR189624>`__)

Improvements and New Features
-----------------------------
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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx2cPapers.csv
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Expand Up @@ -207,7 +207,7 @@
"`P3826R5 <https://wg21.link/P3826R5>`__","Fix Sender Algorithm Customization","2026-03 (Croydon)","","","`#189620 <https://github.com/llvm/llvm-project/issues/189620>`__",""
"`P3980R1 <https://wg21.link/P3980R1>`__","Task's Allocator Use","2026-03 (Croydon)","","","`#189621 <https://github.com/llvm/llvm-project/issues/189621>`__",""
"`P4156R0 <https://wg21.link/P4156R0>`__","Rename meta::has_ellipsis_parameter to meta::is_vararg_function","2026-03 (Croydon)","","","`#189622 <https://github.com/llvm/llvm-project/issues/189622>`__",""
"`P3953R3 <https://wg21.link/P3953R3>`__","Rename ``std::runtime_format``","2026-03 (Croydon)","","","`#189624 <https://github.com/llvm/llvm-project/issues/189624>`__",""
"`P3953R3 <https://wg21.link/P3953R3>`__","Rename ``std::runtime_format``","2026-03 (Croydon)","|Complete|","23","`#189624 <https://github.com/llvm/llvm-project/issues/189624>`__",""
"`P4052R0 <https://wg21.link/P4052R0>`__","Renaming saturation arithmetic functions","2026-03 (Croydon)","","","`#189589 <https://github.com/llvm/llvm-project/issues/189589>`__",""
"`P3941R4 <https://wg21.link/P3941R4>`__","Scheduler Affinity","2026-03 (Croydon)","","","`#189627 <https://github.com/llvm/llvm-project/issues/189627>`__",""
"`P3856R8 <https://wg21.link/P3856R8>`__","New reflection metafunction - is_structural_type (US NB comment 49)","2026-03 (Croydon)","","","`#189625 <https://github.com/llvm/llvm-project/issues/189625>`__",""
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14 changes: 7 additions & 7 deletions libcxx/include/__format/format_functions.h
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Expand Up @@ -342,23 +342,23 @@ _LIBCPP_HIDE_FROM_ABI constexpr typename _Ctx::iterator __vformat_to(_ParseCtx&&

# if _LIBCPP_STD_VER >= 26
template <class _CharT>
struct __runtime_format_string {
struct __dynamic_format_string {
private:
basic_string_view<_CharT> __str_;

template <class _Cp, class... _Args>
friend struct basic_format_string;

public:
_LIBCPP_HIDE_FROM_ABI __runtime_format_string(basic_string_view<_CharT> __s) noexcept : __str_(__s) {}
_LIBCPP_HIDE_FROM_ABI __dynamic_format_string(basic_string_view<_CharT> __s) noexcept : __str_(__s) {}

__runtime_format_string(const __runtime_format_string&) = delete;
__runtime_format_string& operator=(const __runtime_format_string&) = delete;
__dynamic_format_string(const __dynamic_format_string&) = delete;
__dynamic_format_string& operator=(const __dynamic_format_string&) = delete;
};

_LIBCPP_HIDE_FROM_ABI inline __runtime_format_string<char> runtime_format(string_view __fmt) noexcept { return __fmt; }
_LIBCPP_HIDE_FROM_ABI inline __dynamic_format_string<char> dynamic_format(string_view __fmt) noexcept { return __fmt; }
# if _LIBCPP_HAS_WIDE_CHARACTERS
_LIBCPP_HIDE_FROM_ABI inline __runtime_format_string<wchar_t> runtime_format(wstring_view __fmt) noexcept {
_LIBCPP_HIDE_FROM_ABI inline __dynamic_format_string<wchar_t> dynamic_format(wstring_view __fmt) noexcept {
return __fmt;
}
# endif
Expand All @@ -375,7 +375,7 @@ struct basic_format_string {

_LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<_CharT> get() const noexcept { return __str_; }
# if _LIBCPP_STD_VER >= 26
_LIBCPP_HIDE_FROM_ABI basic_format_string(__runtime_format_string<_CharT> __s) noexcept : __str_(__s.__str_) {}
_LIBCPP_HIDE_FROM_ABI basic_format_string(__dynamic_format_string<_CharT> __s) noexcept : __str_(__s.__str_) {}
# endif

private:
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14 changes: 7 additions & 7 deletions libcxx/include/format
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Expand Up @@ -31,7 +31,7 @@ namespace std {

public:
template<class T> consteval basic_format_string(const T& s);
basic_format_string(runtime-format-string<charT> s) noexcept : str(s.str) {} // since C++26
basic_format_string(dynamic-format-string<charT> s) noexcept : str(s.str) {} // since C++26

constexpr basic_string_view<charT> get() const noexcept { return str; }
};
Expand All @@ -42,21 +42,21 @@ namespace std {
using wformat_string = // since C++23, exposition only before C++23
basic_format_string<wchar_t, type_identity_t<Args>...>;

template<class charT> struct runtime-format-string { // since C++26, exposition-only
template<class charT> struct dynamic-format-string { // since C++26, exposition-only
private:
basic_string_view<charT> str; // exposition-only

public:
runtime-format-string(basic_string_view<charT> s) noexcept : str(s) {}
dynamic-format-string(basic_string_view<charT> s) noexcept : str(s) {}

runtime-format-string(const runtime-format-string&) = delete;
runtime-format-string& operator=(const runtime-format-string&) = delete;
dynamic-format-string(const dynamic-format-string&) = delete;
dynamic-format-string& operator=(const dynamic-format-string&) = delete;
};

runtime-format-string<char> runtime_format(string_view fmt) noexcept {
dynamic-format-string<char> dynamic_format(string_view fmt) noexcept {
return fmt;
}
runtime-format-string<wchar_t> runtime_format(wstring_view fmt) noexcept {
dynamic-format-string<wchar_t> dynamic_format(wstring_view fmt) noexcept {
return fmt;
}

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2 changes: 1 addition & 1 deletion libcxx/modules/std/format.inc
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Expand Up @@ -29,7 +29,7 @@ export namespace std {
using std::wformat_string;
#endif
#if _LIBCPP_STD_VER >= 26
using std::runtime_format;
using std::dynamic_format;
#endif // _LIBCPP_STD_VER >= 26

// [format.functions], formatting functions
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14 changes: 7 additions & 7 deletions ...tring/ctor.runtime-format-string.pass.cpp → ...tring/ctor.dynamic-format-string.pass.cpp
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Expand Up @@ -13,28 +13,28 @@
// template<class charT, class... Args>
// class basic_format_string<charT, type_identity_t<Args>...>
//
// basic_format_string(runtime-format-string<charT> s) noexcept : str(s.str) {}
// basic_format_string(dynamic-format-string<charT> s) noexcept : str(s.str) {}
//
// Additional testing is done in
// - libcxx/test/std/utilities/format/format.functions/format.runtime_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.locale.runtime_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.dynamic_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.locale.dynamic_format.pass.cpp

#include <format>
#include <cassert>

#include "test_macros.h"

int main(int, char**) {
static_assert(noexcept(std::format_string<>{std::runtime_format(std::string_view{})}));
static_assert(noexcept(std::format_string<>{std::dynamic_format(std::string_view{})}));
{
std::format_string<> s = std::runtime_format("}{invalid format string}{");
std::format_string<> s = std::dynamic_format("}{invalid format string}{");
assert(s.get() == "}{invalid format string}{");
}

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
static_assert(noexcept(std::wformat_string<>{std::runtime_format(std::wstring_view{})}));
static_assert(noexcept(std::wformat_string<>{std::dynamic_format(std::wstring_view{})}));
{
std::wformat_string<> s = std::runtime_format(L"}{invalid format string}{");
std::wformat_string<> s = std::dynamic_format(L"}{invalid format string}{");
assert(s.get() == L"}{invalid format string}{");
}
#endif // TEST_HAS_NO_WIDE_CHARACTERS
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16 changes: 8 additions & 8 deletions ....functions/format.runtime_format.pass.cpp → ....functions/format.dynamic_format.pass.cpp
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Expand Up @@ -15,15 +15,15 @@

// Tests the behavior of
//
// runtime-format-string<char> runtime_format(string_view fmt) noexcept;
// runtime-format-string<wchar_t> runtime_format(wstring_view fmt) noexcept;
// dynamic-format-string<char> dynamic_format(string_view fmt) noexcept;
// dynamic-format-string<wchar_t> dynamic_format(wstring_view fmt) noexcept;
//
// and
//
// template<class charT, class... Args>
// struct basic_format_string {
// ...
// basic_format_string(runtime-format-string<charT> s) noexcept : str(s.str) {}
// basic_format_string(dynamic-format-string<charT> s) noexcept : str(s.str) {}
// ...
// }
//
Expand All @@ -34,9 +34,9 @@
// template<class... Args>
// wstring format(wformat_string<Args...> fmt, Args&&... args);
//
// The basics of runtime_format and basic_format_string's constructor are tested in
// - libcxx/test/std/utilities/format/format.syn/runtime_format_string.pass.cpp
// - libcxx/test/std/utilities/format/format.fmt.string/ctor.runtime-format-string.pass.cpp
// The basics of dynamic_format and basic_format_string's constructor are tested in
// - libcxx/test/std/utilities/format/format.syn/dynamic_format_string.pass.cpp
// - libcxx/test/std/utilities/format/format.fmt.string/ctor.dynamic-format-string.pass.cpp

#include <format>
#include <cassert>
Expand All @@ -50,7 +50,7 @@

auto test = []<class CharT, class... Args>(
std::basic_string_view<CharT> expected, std::basic_string_view<CharT> fmt, Args&&... args) constexpr {
std::basic_string<CharT> out = std::format(std::runtime_format(fmt), std::forward<Args>(args)...);
std::basic_string<CharT> out = std::format(std::dynamic_format(fmt), std::forward<Args>(args)...);
TEST_REQUIRE(out == expected,
TEST_WRITE_CONCATENATED(
"\nFormat string ", fmt, "\nExpected output ", expected, "\nActual output ", out, '\n'));
Expand All @@ -69,7 +69,7 @@ auto test_exception =
TEST_WRITE_CONCATENATED(
"\nFormat string ", fmt, "\nExpected exception ", what, "\nActual exception ", e.what(), '\n'));
},
TEST_IGNORE_NODISCARD std::format(std::runtime_format(fmt), std::forward<Args>(args)...));
TEST_IGNORE_NODISCARD std::format(std::dynamic_format(fmt), std::forward<Args>(args)...));
};

int main(int, char**) {
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16 changes: 8 additions & 8 deletions ...ons/format.locale.runtime_format.pass.cpp → ...ons/format.locale.dynamic_format.pass.cpp
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Expand Up @@ -16,15 +16,15 @@

// Tests the behavior of
//
// runtime-format-string<char> runtime_format(string_view fmt) noexcept;
// runtime-format-string<wchar_t> runtime_format(wstring_view fmt) noexcept;
// dynamic-format-string<char> dynamic_format(string_view fmt) noexcept;
// dynamic-format-string<wchar_t> dynamic_format(wstring_view fmt) noexcept;
//
// and
//
// template<class charT, class... Args>
// struct basic_format_string {
// ...
// basic_format_string(runtime-format-string<charT> s) noexcept : str(s.str) {}
// basic_format_string(dynamic-format-string<charT> s) noexcept : str(s.str) {}
// ...
// }
//
Expand All @@ -35,9 +35,9 @@
// template<class... Args>
// wstring format(const locale& loc, wformat_string<Args...> fmt, Args&&... args);
//
// The basics of runtime_format and basic_format_string's constructor are tested in
// - libcxx/test/std/utilities/format/format.syn/runtime_format_string.pass.cpp
// - libcxx/test/std/utilities/format/format.fmt.string/ctor.runtime-format-string.pass.cpp
// The basics of dynamic_format and basic_format_string's constructor are tested in
// - libcxx/test/std/utilities/format/format.syn/dynamic_format_string.pass.cpp
// - libcxx/test/std/utilities/format/format.fmt.string/ctor.dynamic-format-string.pass.cpp

#include <format>
#include <cassert>
Expand All @@ -52,7 +52,7 @@

auto test = []<class CharT, class... Args>(
std::basic_string_view<CharT> expected, std::basic_string_view<CharT> fmt, Args&&... args) constexpr {
std::basic_string<CharT> out = std::format(std::locale(), std::runtime_format(fmt), std::forward<Args>(args)...);
std::basic_string<CharT> out = std::format(std::locale(), std::dynamic_format(fmt), std::forward<Args>(args)...);
TEST_REQUIRE(out == expected,
TEST_WRITE_CONCATENATED(
"\nFormat string ", fmt, "\nExpected output ", expected, "\nActual output ", out, '\n'));
Expand All @@ -71,7 +71,7 @@ auto test_exception =
TEST_WRITE_CONCATENATED(
"\nFormat string ", fmt, "\nExpected exception ", what, "\nActual exception ", e.what(), '\n'));
},
TEST_IGNORE_NODISCARD std::format(std::locale(), std::runtime_format(fmt), std::forward<Args>(args)...));
TEST_IGNORE_NODISCARD std::format(std::locale(), std::dynamic_format(fmt), std::forward<Args>(args)...));
};

int main(int, char**) {
Expand Down
28 changes: 14 additions & 14 deletions ...format.syn/runtime_format_string.pass.cpp → ...format.syn/dynamic_format_string.pass.cpp
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Expand Up @@ -10,23 +10,23 @@

// <format>

// template<class charT> struct runtime-format-string { // exposition-only
// template<class charT> struct dynamic-format-string { // exposition-only
// private:
// basic_string_view<charT> str; // exposition-only
//
// public:
// runtime-format-string(basic_string_view<charT> s) noexcept : str(s) {}
// dynamic-format-string(basic_string_view<charT> s) noexcept : str(s) {}
//
// runtime-format-string(const runtime-format-string&) = delete;
// runtime-format-string& operator=(const runtime-format-string&) = delete;
// dynamic-format-string(const dynamic-format-string&) = delete;
// dynamic-format-string& operator=(const dynamic-format-string&) = delete;
// };
//
// runtime-format-string<char> runtime_format(string_view fmt) noexcept;
// runtime-format-string<wchar_t> runtime_format(wstring_view fmt) noexcept;
// dynamic-format-string<char> dynamic_format(string_view fmt) noexcept;
// dynamic-format-string<wchar_t> dynamic_format(wstring_view fmt) noexcept;
//
// Additional testing is done in
// - libcxx/test/std/utilities/format/format.functions/format.runtime_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.locale.runtime_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.dynamic_format.pass.cpp
// - libcxx/test/std/utilities/format/format.functions/format.locale.dynamic_format.pass.cpp

#include <format>

Expand All @@ -50,19 +50,19 @@ static void test_properties() {
}

int main(int, char**) {
static_assert(noexcept(std::runtime_format(std::string_view{})));
auto format_string = std::runtime_format(std::string_view{});
static_assert(noexcept(std::dynamic_format(std::string_view{})));
auto format_string = std::dynamic_format(std::string_view{});

using FormatString = decltype(format_string);
LIBCPP_ASSERT((std::same_as<FormatString, std::__runtime_format_string<char>>));
LIBCPP_ASSERT((std::same_as<FormatString, std::__dynamic_format_string<char>>));
test_properties<FormatString, char>();

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
static_assert(noexcept(std::runtime_format(std::wstring_view{})));
auto wformat_string = std::runtime_format(std::wstring_view{});
static_assert(noexcept(std::dynamic_format(std::wstring_view{})));
auto wformat_string = std::dynamic_format(std::wstring_view{});

using WFormatString = decltype(wformat_string);
LIBCPP_ASSERT((std::same_as<WFormatString, std::__runtime_format_string<wchar_t>>));
LIBCPP_ASSERT((std::same_as<WFormatString, std::__dynamic_format_string<wchar_t>>));
test_properties<WFormatString, wchar_t>();
#endif // TEST_HAS_NO_WIDE_CHARACTERS

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1 change: 1 addition & 0 deletions libcxx/utils/generate_feature_test_macro_components.py
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Expand Up @@ -572,6 +572,7 @@ def add_version_header(tc):
# "c++23": 202207, Not implemented P2419R2 Clarify handling of encodings in localized formatting of chrono types
# "c++26": 202306, P2637R3 Member Visit (implemented)
# "c++26": 202311, P2918R2 Runtime format strings II (implemented)
# "c++26": 202603, P3953R3 Rename std::runtime_format (implemented)
},
# Note these three papers are adopted at the June 2023 meeting and have sequential numbering
# 202304 P2510R3 Formatting pointers (Implemented)
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