WIP - [libc++][string] P2587R3: to_string or not to_string

libcxx/docs/FeatureTestMacroTable.rst

@@ -514,7 +514,7 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_to_chars``                                     *unimplemented*
     ---------------------------------------------------------- -----------------
-    ``__cpp_lib_to_string``                                    *unimplemented*
+    ``__cpp_lib_to_string``                                    ``202306L``
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_tuple_like``                                   *unimplemented*
     ---------------------------------------------------------- -----------------

libcxx/docs/Status/Cxx2cPapers.csv

@@ -1,4 +1,33 @@
 "Paper #","Paper Name","Meeting","Status","First released version","Notes"
+<<<<<<< HEAD
+"`P2497R0 <https://wg21.link/P2497R0>`__","Testing for success or failure of ``<charconv>`` functions","2023-06 (Varna)","|Complete|","18",""
+"`P2592R3 <https://wg21.link/P2592R3>`__","Hashing support for ``std::chrono`` value classes","2023-06 (Varna)","","",""
+"`P2587R3 <https://wg21.link/P2587R3>`__","``to_string`` or not ``to_string``","2023-06 (Varna)","|Complete|","XX",""
+"`P2562R1 <https://wg21.link/P2562R1>`__","``constexpr`` Stable Sorting","2023-06 (Varna)","|Partial|","20",""
+"`P2545R4 <https://wg21.link/P2545R4>`__","Read-Copy Update (RCU)","2023-06 (Varna)","","",""
+"`P2530R3 <https://wg21.link/P2530R3>`__","Hazard Pointers for C++26","2023-06 (Varna)","","",""
+"`P2538R1 <https://wg21.link/P2538R1>`__","ADL-proof ``std::projected``","2023-06 (Varna)","|Complete|","18",""
+"`P2495R3 <https://wg21.link/P2495R3>`__","Interfacing ``stringstream``\s with ``string_view``","2023-06 (Varna)","|Complete|","19",""
+"`P2510R3 <https://wg21.link/P2510R3>`__","Formatting pointers","2023-06 (Varna)","|Complete|","17","Implemented as a DR against C++20. (MSVC STL and libstdc++ will do the same.)"
+"`P2198R7 <https://wg21.link/P2198R7>`__","Freestanding Feature-Test Macros and Implementation-Defined Extensions","2023-06 (Varna)","","",""
+"`P2338R4 <https://wg21.link/P2338R4>`__","Freestanding Library: Character primitives and the C library","2023-06 (Varna)","","",""
+"`P2013R5 <https://wg21.link/P2013R5>`__","Freestanding Language: Optional ``::operator new``","2023-06 (Varna)","","",""
+"`P2363R5 <https://wg21.link/P2363R5>`__","Extending associative containers with the remaining heterogeneous overloads","2023-06 (Varna)","","",""
+"`P1901R2 <https://wg21.link/P1901R2>`__","Enabling the Use of ``weak_ptr`` as Keys in Unordered Associative Containers","2023-06 (Varna)","","",""
+"`P1885R12 <https://wg21.link/P1885R12>`__","Naming Text Encodings to Demystify Them","2023-06 (Varna)","","",""
+"`P0792R14 <https://wg21.link/P0792R14>`__","``function_ref``: a type-erased callable reference","2023-06 (Varna)","","",""
+"`P2874R2 <https://wg21.link/P2874R2>`__","P2874R2: Mandating Annex D Require No More","2023-06 (Varna)","|Complete|","12",""
+"`P2757R3 <https://wg21.link/P2757R3>`__","Type-checking format args","2023-06 (Varna)","","",""
+"`P2637R3 <https://wg21.link/P2637R3>`__","Member ``visit``","2023-06 (Varna)","|Complete|","19","Change of ``__cpp_lib_variant`` is completed in LLVM 20. Change of ``__cpp_lib_format`` is blocked by `P2419R2 <https://wg21.link/P2419R2>`__."
+"`P2641R4 <https://wg21.link/P2641R4>`__","Checking if a ``union`` alternative is active","2023-06 (Varna)","","",""
+"`P1759R6 <https://wg21.link/P1759R6>`__","Native handles and file streams","2023-06 (Varna)","|Complete|","18",""
+"`P2697R1 <https://wg21.link/P2697R1>`__","Interfacing ``bitset`` with ``string_view``","2023-06 (Varna)","|Complete|","18",""
+"`P1383R2 <https://wg21.link/P1383R2>`__","More ``constexpr`` for ``<cmath>`` and ``<complex>``","2023-06 (Varna)","","",""
+"`P2734R0 <https://wg21.link/P2734R0>`__","Adding the new SI prefixes","2023-06 (Varna)","|Complete|","17",""
+"`P2548R6 <https://wg21.link/P2548R6>`__","``copyable_function``","2023-06 (Varna)","","",""
+"`P2714R1 <https://wg21.link/P2714R1>`__","Bind front and back to NTTP callables","2023-06 (Varna)","|Partial|","20",""
+"`P2630R4 <https://wg21.link/P2630R4>`__","``submdspan``","2023-06 (Varna)","","",""
+=======
 "`P2497R0 <https://wg21.link/P2497R0>`__","Testing for success or failure of ``<charconv>`` functions","2023-06 (Varna)","|Complete|","18","`#105357 <https://github.com/llvm/llvm-project/issues/105357>`__",""
 "`P2592R3 <https://wg21.link/P2592R3>`__","Hashing support for ``std::chrono`` value classes","2023-06 (Varna)","","","`#105358 <https://github.com/llvm/llvm-project/issues/105358>`__",""
 "`P2587R3 <https://wg21.link/P2587R3>`__","``to_string`` or not ``to_string``","2023-06 (Varna)","","","`#105359 <https://github.com/llvm/llvm-project/issues/105359>`__",""
@@ -26,6 +55,7 @@
 "`P2548R6 <https://wg21.link/P2548R6>`__","``copyable_function``","2023-06 (Varna)","","","`#105387 <https://github.com/llvm/llvm-project/issues/105387>`__",""
 "`P2714R1 <https://wg21.link/P2714R1>`__","Bind front and back to NTTP callables","2023-06 (Varna)","|Partial|","20","`#105388 <https://github.com/llvm/llvm-project/issues/105388>`__",""
 "`P2630R4 <https://wg21.link/P2630R4>`__","``submdspan``","2023-06 (Varna)","","","`#105389 <https://github.com/llvm/llvm-project/issues/105389>`__",""
+>>>>>>> main
 "","","","","",""
 "`P0543R3 <https://wg21.link/P0543R3>`__","Saturation arithmetic","2023-11 (Kona)","|Complete|","18","`#105390 <https://github.com/llvm/llvm-project/issues/105390>`__",""
 "`P2407R5 <https://wg21.link/P2407R5>`__","Freestanding Library: Partial Classes","2023-11 (Kona)","","","`#105391 <https://github.com/llvm/llvm-project/issues/105391>`__",""

libcxx/include/string

@@ -3912,9 +3912,20 @@ _LIBCPP_EXPORTED_FROM_ABI string to_string(long __val);
 _LIBCPP_EXPORTED_FROM_ABI string to_string(unsigned long __val);
 _LIBCPP_EXPORTED_FROM_ABI string to_string(long long __val);
 _LIBCPP_EXPORTED_FROM_ABI string to_string(unsigned long long __val);
+
+#  if _LIBCPP_STD_VER >= 26
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(float __val);
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(double __val);
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(long double __val);
+
+_LIBCPP_HIDE_FROM_ABI string to_string(float __val) { return std::__to_string(__val); }
+_LIBCPP_HIDE_FROM_ABI string to_string(double __val) { return std::__to_string(__val); }
+_LIBCPP_HIDE_FROM_ABI string to_string(long double __val) { return std::__to_string(__val); }
+#  else
 _LIBCPP_EXPORTED_FROM_ABI string to_string(float __val);
 _LIBCPP_EXPORTED_FROM_ABI string to_string(double __val);
 _LIBCPP_EXPORTED_FROM_ABI string to_string(long double __val);
+#  endif // _LIBCPP_STD_VER >= 26
 
 #  if _LIBCPP_HAS_WIDE_CHARACTERS
 _LIBCPP_EXPORTED_FROM_ABI int stoi(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
@@ -3933,9 +3944,20 @@ _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long __val);
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(unsigned long __val);
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long long __val);
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(unsigned long long __val);
+
+#    if _LIBCPP_STD_VER >= 26
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(float __val);
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(double __val);
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(long double __val);
+
+_LIBCPP_HIDE_FROM_ABI wstring to_wstring(float __val) { return std::__to_wstring(__val); }
+_LIBCPP_HIDE_FROM_ABI wstring to_wstring(double __val) { return std::__to_wstring(__val); }
+_LIBCPP_HIDE_FROM_ABI wstring to_wstring(long double __val) { return std::__to_wstring(__val); }
+#    else
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(float __val);
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(double __val);
 _LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long double __val);
+#    endif
 #  endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 template <class _CharT, class _Traits, class _Allocator>

libcxx/include/version

@@ -605,7 +605,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 // # define __cpp_lib_text_encoding                        202306L
 # undef  __cpp_lib_to_chars
 // # define __cpp_lib_to_chars                             202306L
-// # define __cpp_lib_to_string                            202306L
+# define __cpp_lib_to_string                            202306L
 # undef  __cpp_lib_tuple_like
 // # define __cpp_lib_tuple_like                           202311L
 # undef  __cpp_lib_variant

libcxx/src/string.cpp

@@ -10,6 +10,7 @@
 #include <cerrno>
 #include <charconv>
 #include <cstdlib>
+#include <format>
 #include <limits>
 #include <stdexcept>
 #include <string>
@@ -372,6 +373,16 @@ wstring to_wstring(unsigned long val) { return i_to_string<wstring>(val); }
 wstring to_wstring(unsigned long long val) { return i_to_string<wstring>(val); }
 #endif
 
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(float __val) { return std::format("{}", __val); }
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(double __val) { return std::format("{}", __val); }
+_LIBCPP_EXPORTED_FROM_ABI string __to_string(long double __val) { return std::format("{}", __val); }
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(float __val) { return std::format(L"{}", __val); }
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(double __val) { return std::format(L"{}", __val); }
+_LIBCPP_EXPORTED_FROM_ABI wstring __to_wstring(long double __val) { return std::format(L"{}", __val); }
+#endif
+
 string to_string(float val) { return as_string(snprintf, initial_string< string>()(), "%f", val); }
 string to_string(double val) { return as_string(snprintf, initial_string< string>()(), "%f", val); }
 string to_string(long double val) { return as_string(snprintf, initial_string< string>()(), "%Lf", val); }

libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp

@@ -470,6 +470,14 @@
 #    error "__cpp_lib_string_view should have the value 202403L in c++26"
 #  endif
 
+<<<<<<< HEAD
+# ifndef __cpp_lib_to_string
+#   error "__cpp_lib_to_string should be defined in c++26"
+# endif
+# if __cpp_lib_to_string != 202306L
+#   error "__cpp_lib_to_string should have the value 202306L in c++26"
+# endif
+=======
 #  if !defined(_LIBCPP_VERSION)
 #    ifndef __cpp_lib_to_string
 #      error "__cpp_lib_to_string should be defined in c++26"
@@ -482,6 +490,7 @@
 #      error "__cpp_lib_to_string should not be defined because it is unimplemented in libc++!"
 #    endif
 #  endif
+>>>>>>> main
 
 #endif // TEST_STD_VER > 23