Implement LWG-3834 Missing constexpr for std::intmax_t math functions in <cinttypes>

stl/CMakeLists.txt

@@ -16,6 +16,7 @@ set(HEADERS
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_formatter.hpp
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_heap_algorithms.hpp
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_int128.hpp
+    ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_inttypes.hpp
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_iter_core.hpp
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_math.hpp
     ${CMAKE_CURRENT_LIST_DIR}/inc/__msvc_minmax.hpp

stl/inc/__msvc_inttypes.hpp

@@ -0,0 +1,315 @@
+// __msvc_inttypes.hpp internal header (core)
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// This file was derived from <inttypes.h> in the Windows 11 SDK (10.0.28000), with some alterations:
+// * Formatted with clang-format.
+// * Changed code to support the MSVC frontend intercepting inclusions of <inttypes.h>.
+// * Changed code for C++23's LWG-3834 "Missing constexpr for std::intmax_t math functions in <cinttypes>".
+// Avoid introducing further unnecessary divergence between <inttypes.h> and this file.
+
+#ifndef __MSVC_INTTYPES_HPP
+#define __MSVC_INTTYPES_HPP
+
+// Prevent later inclusions of <inttypes.h> from having any effect.
+#define _INTTYPES
+
+#include <corecrt.h>
+#include <stdint.h>
+
+#pragma warning(push)
+#pragma warning(disable : _UCRT_DISABLED_WARNINGS)
+_UCRT_DISABLE_CLANG_WARNINGS
+
+_CRT_BEGIN_C_HEADER
+
+
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Types
+//
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+typedef struct {
+    intmax_t quot;
+    intmax_t rem;
+} _Lldiv_t;
+
+typedef _Lldiv_t imaxdiv_t;
+
+
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Functions
+//
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+// inttypes functions that became constexpr in C++23
+#if _HAS_CXX23 && defined(_MSVC_LIBC_MATH)
+#define _CONSTEXPR_CINTTYPES23 constexpr
+#else // ^^^ constexpr in C++23 and later / inline when /Zc:cmath- opts out of constexpr, and in C++20 and earlier vvv
+#define _CONSTEXPR_CINTTYPES23 inline
+#endif // ^^^ inline when /Zc:cmath- opts out of constexpr, and in C++20 and earlier ^^^
+
+[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 intmax_t __cdecl imaxabs(_In_ intmax_t _Number) noexcept
+/* strengthened */ {
+    return _Number >= 0 ? _Number : -_Number;
+}
+
+[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 imaxdiv_t __cdecl imaxdiv(
+    _In_ intmax_t _Numerator, _In_ intmax_t _Denominator) noexcept /* strengthened */ {
+    return {_Numerator / _Denominator, _Numerator % _Denominator};
+}
+
+#undef _CONSTEXPR_CINTTYPES23
+
+_ACRTIMP intmax_t __cdecl strtoimax(
+    _In_z_ char const* _String, _Out_opt_ _Deref_post_z_ char** _EndPtr, _In_ int _Radix);
+
+_ACRTIMP intmax_t __cdecl _strtoimax_l(
+    _In_z_ char const* _String, _Out_opt_ _Deref_post_z_ char** _EndPtr, _In_ int _Radix, _In_opt_ _locale_t _Locale);
+
+_ACRTIMP uintmax_t __cdecl strtoumax(
+    _In_z_ char const* _String, _Out_opt_ _Deref_post_z_ char** _EndPtr, _In_ int _Radix);
+
+_ACRTIMP uintmax_t __cdecl _strtoumax_l(
+    _In_z_ char const* _String, _Out_opt_ _Deref_post_z_ char** _EndPtr, _In_ int _Radix, _In_opt_ _locale_t _Locale);
+
+_ACRTIMP intmax_t __cdecl wcstoimax(
+    _In_z_ wchar_t const* _String, _Out_opt_ _Deref_post_z_ wchar_t** _EndPtr, _In_ int _Radix);
+
+_ACRTIMP intmax_t __cdecl _wcstoimax_l(_In_z_ wchar_t const* _String, _Out_opt_ _Deref_post_z_ wchar_t** _EndPtr,
+    _In_ int _Radix, _In_opt_ _locale_t _Locale);
+
+_ACRTIMP uintmax_t __cdecl wcstoumax(
+    _In_z_ wchar_t const* _String, _Out_opt_ _Deref_post_z_ wchar_t** _EndPtr, _In_ int _Radix);
+
+_ACRTIMP uintmax_t __cdecl _wcstoumax_l(_In_z_ wchar_t const* _String, _Out_opt_ _Deref_post_z_ wchar_t** _EndPtr,
+    _In_ int _Radix, _In_opt_ _locale_t _Locale);
+
+
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Output Format Specifier Macros
+//
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+#define PRId8       "hhd"
+#define PRId16      "hd"
+#define PRId32      "d"
+#define PRId64      "lld"
+#define PRIdLEAST8  PRId8
+#define PRIdLEAST16 PRId16
+#define PRIdLEAST32 PRId32
+#define PRIdLEAST64 PRId64
+#define PRIdFAST8   PRId8
+#define PRIdFAST16  PRId32
+#define PRIdFAST32  PRId32
+#define PRIdFAST64  PRId64
+#define PRIdMAX     PRId64
+#ifdef _WIN64
+#define PRIdPTR PRId64
+#else
+#define PRIdPTR PRId32
+#endif
+
+#define PRIi8       "hhi"
+#define PRIi16      "hi"
+#define PRIi32      "i"
+#define PRIi64      "lli"
+#define PRIiLEAST8  PRIi8
+#define PRIiLEAST16 PRIi16
+#define PRIiLEAST32 PRIi32
+#define PRIiLEAST64 PRIi64
+#define PRIiFAST8   PRIi8
+#define PRIiFAST16  PRIi32
+#define PRIiFAST32  PRIi32
+#define PRIiFAST64  PRIi64
+#define PRIiMAX     PRIi64
+#ifdef _WIN64
+#define PRIiPTR PRIi64
+#else
+#define PRIiPTR PRIi32
+#endif
+
+#define PRIo8       "hho"
+#define PRIo16      "ho"
+#define PRIo32      "o"
+#define PRIo64      "llo"
+#define PRIoLEAST8  PRIo8
+#define PRIoLEAST16 PRIo16
+#define PRIoLEAST32 PRIo32
+#define PRIoLEAST64 PRIo64
+#define PRIoFAST8   PRIo8
+#define PRIoFAST16  PRIo32
+#define PRIoFAST32  PRIo32
+#define PRIoFAST64  PRIo64
+#define PRIoMAX     PRIo64
+#ifdef _WIN64
+#define PRIoPTR PRIo64
+#else
+#define PRIoPTR PRIo32
+#endif
+
+#define PRIu8       "hhu"
+#define PRIu16      "hu"
+#define PRIu32      "u"
+#define PRIu64      "llu"
+#define PRIuLEAST8  PRIu8
+#define PRIuLEAST16 PRIu16
+#define PRIuLEAST32 PRIu32
+#define PRIuLEAST64 PRIu64
+#define PRIuFAST8   PRIu8
+#define PRIuFAST16  PRIu32
+#define PRIuFAST32  PRIu32
+#define PRIuFAST64  PRIu64
+#define PRIuMAX     PRIu64
+#ifdef _WIN64
+#define PRIuPTR PRIu64
+#else
+#define PRIuPTR PRIu32
+#endif
+
+#define PRIx8       "hhx"
+#define PRIx16      "hx"
+#define PRIx32      "x"
+#define PRIx64      "llx"
+#define PRIxLEAST8  PRIx8
+#define PRIxLEAST16 PRIx16
+#define PRIxLEAST32 PRIx32
+#define PRIxLEAST64 PRIx64
+#define PRIxFAST8   PRIx8
+#define PRIxFAST16  PRIx32
+#define PRIxFAST32  PRIx32
+#define PRIxFAST64  PRIx64
+#define PRIxMAX     PRIx64
+#ifdef _WIN64
+#define PRIxPTR PRIx64
+#else
+#define PRIxPTR PRIx32
+#endif
+
+#define PRIX8       "hhX"
+#define PRIX16      "hX"
+#define PRIX32      "X"
+#define PRIX64      "llX"
+#define PRIXLEAST8  PRIX8
+#define PRIXLEAST16 PRIX16
+#define PRIXLEAST32 PRIX32
+#define PRIXLEAST64 PRIX64
+#define PRIXFAST8   PRIX8
+#define PRIXFAST16  PRIX32
+#define PRIXFAST32  PRIX32
+#define PRIXFAST64  PRIX64
+#define PRIXMAX     PRIX64
+#ifdef _WIN64
+#define PRIXPTR PRIX64
+#else
+#define PRIXPTR PRIX32
+#endif
+
+
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Input Format Specifier Macros
+//
+//-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+#define SCNd8       "hhd"
+#define SCNd16      "hd"
+#define SCNd32      "d"
+#define SCNd64      "lld"
+#define SCNdLEAST8  SCNd8
+#define SCNdLEAST16 SCNd16
+#define SCNdLEAST32 SCNd32
+#define SCNdLEAST64 SCNd64
+#define SCNdFAST8   SCNd8
+#define SCNdFAST16  SCNd32
+#define SCNdFAST32  SCNd32
+#define SCNdFAST64  SCNd64
+#define SCNdMAX     SCNd64
+#ifdef _WIN64
+#define SCNdPTR SCNd64
+#else
+#define SCNdPTR SCNd32
+#endif
+
+#define SCNi8       "hhi"
+#define SCNi16      "hi"
+#define SCNi32      "i"
+#define SCNi64      "lli"
+#define SCNiLEAST8  SCNi8
+#define SCNiLEAST16 SCNi16
+#define SCNiLEAST32 SCNi32
+#define SCNiLEAST64 SCNi64
+#define SCNiFAST8   SCNi8
+#define SCNiFAST16  SCNi32
+#define SCNiFAST32  SCNi32
+#define SCNiFAST64  SCNi64
+#define SCNiMAX     SCNi64
+#ifdef _WIN64
+#define SCNiPTR SCNi64
+#else
+#define SCNiPTR SCNi32
+#endif
+
+#define SCNo8       "hho"
+#define SCNo16      "ho"
+#define SCNo32      "o"
+#define SCNo64      "llo"
+#define SCNoLEAST8  SCNo8
+#define SCNoLEAST16 SCNo16
+#define SCNoLEAST32 SCNo32
+#define SCNoLEAST64 SCNo64
+#define SCNoFAST8   SCNo8
+#define SCNoFAST16  SCNo32
+#define SCNoFAST32  SCNo32
+#define SCNoFAST64  SCNo64
+#define SCNoMAX     SCNo64
+#ifdef _WIN64
+#define SCNoPTR SCNo64
+#else
+#define SCNoPTR SCNo32
+#endif
+
+#define SCNu8       "hhu"
+#define SCNu16      "hu"
+#define SCNu32      "u"
+#define SCNu64      "llu"
+#define SCNuLEAST8  SCNu8
+#define SCNuLEAST16 SCNu16
+#define SCNuLEAST32 SCNu32
+#define SCNuLEAST64 SCNu64
+#define SCNuFAST8   SCNu8
+#define SCNuFAST16  SCNu32
+#define SCNuFAST32  SCNu32
+#define SCNuFAST64  SCNu64
+#define SCNuMAX     SCNu64
+#ifdef _WIN64
+#define SCNuPTR SCNu64
+#else
+#define SCNuPTR SCNu32
+#endif
+
+#define SCNx8       "hhx"
+#define SCNx16      "hx"
+#define SCNx32      "x"
+#define SCNx64      "llx"
+#define SCNxLEAST8  SCNx8
+#define SCNxLEAST16 SCNx16
+#define SCNxLEAST32 SCNx32
+#define SCNxLEAST64 SCNx64
+#define SCNxFAST8   SCNx8
+#define SCNxFAST16  SCNx32
+#define SCNxFAST32  SCNx32
+#define SCNxFAST64  SCNx64
+#define SCNxMAX     SCNx64
+#ifdef _WIN64
+#define SCNxPTR SCNx64
+#else
+#define SCNxPTR SCNx32
+#endif
+
+
+_CRT_END_C_HEADER
+_UCRT_RESTORE_CLANG_WARNINGS
+#pragma warning(pop) // _UCRT_DISABLED_WARNINGS
+#endif // __MSVC_INTTYPES_HPP

stl/inc/header-units.json

@@ -14,6 +14,7 @@
         "__msvc_formatter.hpp",
         "__msvc_heap_algorithms.hpp",
         "__msvc_int128.hpp",
+        "__msvc_inttypes.hpp",
         "__msvc_iter_core.hpp",
         "__msvc_math.hpp",
         "__msvc_minmax.hpp",

tests/std/tests/P0533R9_constexpr_for_cmath_and_cstdlib/test.cpp

@@ -1,7 +1,14 @@
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+// TRANSITION, MSVC frontend needs to intercept inclusions of <inttypes.h>:
+#ifndef _M_CEE_PURE
+#include <__msvc_inttypes.hpp>
+#endif
+// ^^^ workaround ^^^
+
 #include <cassert>
+#include <cinttypes>
 #include <cmath>
 #include <cstdlib>
 #include <limits>
@@ -399,6 +406,17 @@ CONSTEXPR_CMATH23 bool test_cstdlib_cxx23() {
     return true;
 }
 
+CONSTEXPR_CMATH23 bool test_cinttypes_cxx23() {
+    // Test LWG-3834 "Missing constexpr for std::intmax_t math functions in <cinttypes>".
+
+    assert(imaxabs(-5LL) == 5LL);
+
+    assert(imaxdiv(1729LL, 100LL).quot == 17LL);
+    assert(imaxdiv(1729LL, 100LL).rem == 29LL);
+
+    return true;
+}
+
 CONSTEXPR_CMATH26 bool test_cmath_cxx26() {
     // These tests use round() because they're checking for basic functionality, not precision.
 
@@ -657,13 +675,15 @@ int main() {
 #if defined(_MSVC_INTERNAL_TESTING) || !defined(_M_ARM64EC) // TRANSITION, MSVC-PR-767414/MSVC-PR-768260 fixed LNK2019
     test_cmath_cxx23();
     test_cstdlib_cxx23();
+    test_cinttypes_cxx23();
     test_cmath_cxx26();
     test_cmath_runtime();
 #endif // ^^^ no workaround ^^^
 
 #ifdef __cpp_lib_constexpr_cmath
     static_assert(test_cmath_cxx23());
     static_assert(test_cstdlib_cxx23());
+    static_assert(test_cinttypes_cxx23());
 #if _HAS_CXX26 && defined(_MSVC_LIBC_MATH) // TRANSITION, GH-3789, should be `__cpp_lib_constexpr_cmath >= 202306L`
     static_assert(test_cmath_cxx26());
 #endif // ^^^ _HAS_CXX26 && defined(_MSVC_LIBC_MATH) ^^^