[libc++] Don't use static constexpr in headers.

[Mordante]

Summary

This was noticed in the review of D125704. In that commit only the new
table has been adapted. This adapts the existing tables.

Note since libc++'s charconv is backported to C++11 it's not possible to
use inline constexpr variables. The were introduced in C++17.

libcxx/include/__charconv/tables.h

 // -*- 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___CHARCONV_TABLES
 #define _LIBCPP___CHARCONV_TABLES
 
 #include <__config>
+#include <cstdint>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #ifndef _LIBCPP_CXX03_LANG
 
 namespace __itoa {
 
+/// Contains the charconv helper tables.
+///
+/// In C++17 these could be inline constexpr variable, but libc++ supports
+/// charconv for integrals in C++11 mode.
 template <class = void>
-struct __digits_base_10 {
-  static const char __value[200];
+struct __table {
+  static const char __base_2_lut[64];
+  static const char __base_8_lut[128];
+  static const char __base_16_lut[512];
+
+  static const uint32_t __pow10_32[10];
+  static const uint64_t __pow10_64[20];
+  static const char __digits_base_10[200];
 };
 
 template <class _Tp>
-const char __digits_base_10<_Tp>::__value[200] = {
+const char __table<_Tp>::__base_2_lut[64] = {
+    '0', '0', '0', '0', '0', '0', '0', '1', '0', '0', '1', '0', '0', '0', '1', '1', '0', '1', '0', '0', '0', '1',
+    '0', '1', '0', '1', '1', '0', '0', '1', '1', '1', '1', '0', '0', '0', '1', '0', '0', '1', '1', '0', '1', '0',
+    '1', '0', '1', '1', '1', '1', '0', '0', '1', '1', '0', '1', '1', '1', '1', '0', '1', '1', '1', '1'};
+
+template <class _Tp>
+const char __table<_Tp>::__base_8_lut[128] = {
+    '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0', '7', '1', '0', '1', '1', '1', '2',
+    '1', '3', '1', '4', '1', '5', '1', '6', '1', '7', '2', '0', '2', '1', '2', '2', '2', '3', '2', '4', '2', '5',
+    '2', '6', '2', '7', '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '4', '0',
+    '4', '1', '4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7', '5', '0', '5', '1', '5', '2', '5', '3',
+    '5', '4', '5', '5', '5', '6', '5', '7', '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6',
+    '6', '7', '7', '0', '7', '1', '7', '2', '7', '3', '7', '4', '7', '5', '7', '6', '7', '7'};
+
+template <class _Tp>
+const char __table<_Tp>::__base_16_lut[512] = {
+    '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0', '7', '0', '8', '0', '9', '0', 'a', '0',
+    'b', '0', 'c', '0', 'd', '0', 'e', '0', 'f', '1', '0', '1', '1', '1', '2', '1', '3', '1', '4', '1', '5', '1', '6',
+    '1', '7', '1', '8', '1', '9', '1', 'a', '1', 'b', '1', 'c', '1', 'd', '1', 'e', '1', 'f', '2', '0', '2', '1', '2',
+    '2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9', '2', 'a', '2', 'b', '2', 'c', '2', 'd',
+    '2', 'e', '2', 'f', '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '3', '8', '3',
+    '9', '3', 'a', '3', 'b', '3', 'c', '3', 'd', '3', 'e', '3', 'f', '4', '0', '4', '1', '4', '2', '4', '3', '4', '4',
+    '4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '4', 'a', '4', 'b', '4', 'c', '4', 'd', '4', 'e', '4', 'f', '5',
+    '0', '5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9', '5', 'a', '5', 'b',
+    '5', 'c', '5', 'd', '5', 'e', '5', 'f', '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6',
+    '7', '6', '8', '6', '9', '6', 'a', '6', 'b', '6', 'c', '6', 'd', '6', 'e', '6', 'f', '7', '0', '7', '1', '7', '2',
+    '7', '3', '7', '4', '7', '5', '7', '6', '7', '7', '7', '8', '7', '9', '7', 'a', '7', 'b', '7', 'c', '7', 'd', '7',
+    'e', '7', 'f', '8', '0', '8', '1', '8', '2', '8', '3', '8', '4', '8', '5', '8', '6', '8', '7', '8', '8', '8', '9',
+    '8', 'a', '8', 'b', '8', 'c', '8', 'd', '8', 'e', '8', 'f', '9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9',
+    '5', '9', '6', '9', '7', '9', '8', '9', '9', '9', 'a', '9', 'b', '9', 'c', '9', 'd', '9', 'e', '9', 'f', 'a', '0',
+    'a', '1', 'a', '2', 'a', '3', 'a', '4', 'a', '5', 'a', '6', 'a', '7', 'a', '8', 'a', '9', 'a', 'a', 'a', 'b', 'a',
+    'c', 'a', 'd', 'a', 'e', 'a', 'f', 'b', '0', 'b', '1', 'b', '2', 'b', '3', 'b', '4', 'b', '5', 'b', '6', 'b', '7',
+    'b', '8', 'b', '9', 'b', 'a', 'b', 'b', 'b', 'c', 'b', 'd', 'b', 'e', 'b', 'f', 'c', '0', 'c', '1', 'c', '2', 'c',
+    '3', 'c', '4', 'c', '5', 'c', '6', 'c', '7', 'c', '8', 'c', '9', 'c', 'a', 'c', 'b', 'c', 'c', 'c', 'd', 'c', 'e',
+    'c', 'f', 'd', '0', 'd', '1', 'd', '2', 'd', '3', 'd', '4', 'd', '5', 'd', '6', 'd', '7', 'd', '8', 'd', '9', 'd',
+    'a', 'd', 'b', 'd', 'c', 'd', 'd', 'd', 'e', 'd', 'f', 'e', '0', 'e', '1', 'e', '2', 'e', '3', 'e', '4', 'e', '5',
+    'e', '6', 'e', '7', 'e', '8', 'e', '9', 'e', 'a', 'e', 'b', 'e', 'c', 'e', 'd', 'e', 'e', 'e', 'f', 'f', '0', 'f',
+    '1', 'f', '2', 'f', '3', 'f', '4', 'f', '5', 'f', '6', 'f', '7', 'f', '8', 'f', '9', 'f', 'a', 'f', 'b', 'f', 'c',
+    'f', 'd', 'f', 'e', 'f', 'f'};
+
+template <class _Tp>
+const uint32_t __table<_Tp>::__pow10_32[10] = {
+    UINT32_C(0),      UINT32_C(10),      UINT32_C(100),      UINT32_C(1000),      UINT32_C(10000),
+    UINT32_C(100000), UINT32_C(1000000), UINT32_C(10000000), UINT32_C(100000000), UINT32_C(1000000000)};
+
+template <class _Tp>
+const uint64_t __table<_Tp>::__pow10_64[20] = {UINT64_C(0),
+                                               UINT64_C(10),
+                                               UINT64_C(100),
+                                               UINT64_C(1000),
+                                               UINT64_C(10000),
+                                               UINT64_C(100000),
+                                               UINT64_C(1000000),
+                                               UINT64_C(10000000),
+                                               UINT64_C(100000000),
+                                               UINT64_C(1000000000),
+                                               UINT64_C(10000000000),
+                                               UINT64_C(100000000000),
+                                               UINT64_C(1000000000000),
+                                               UINT64_C(10000000000000),
+                                               UINT64_C(100000000000000),
+                                               UINT64_C(1000000000000000),
+                                               UINT64_C(10000000000000000),
+                                               UINT64_C(100000000000000000),
+                                               UINT64_C(1000000000000000000),
+                                               UINT64_C(10000000000000000000)};
+
+template <class _Tp>
+const char __table<_Tp>::__digits_base_10[200] = {
     // clang-format off
     '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0', '7', '0', '8', '0', '9',
     '1', '0', '1', '1', '1', '2', '1', '3', '1', '4', '1', '5', '1', '6', '1', '7', '1', '8', '1', '9',
     '2', '0', '2', '1', '2', '2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9',
     '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '3', '8', '3', '9',
     '4', '0', '4', '1', '4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7', '4', '8', '4', '9',
     '5', '0', '5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
     '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6', '7', '6', '8', '6', '9',

libcxx/include/__charconv/to_chars_base_10.h

 template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI char* __append1(char* __buffer, _Tp __value) noexcept {
   *__buffer = '0' + static_cast<char>(__value);
   return __buffer + 1;
 }
 
 template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI char* __append2(char* __buffer, _Tp __value) noexcept {
-  std::memcpy(__buffer, &__digits_base_10<>::__value[(__value)*2], 2);
+  std::memcpy(__buffer, &__table<>::__digits_base_10[(__value)*2], 2);
   return __buffer + 2;
 }
 
 template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI char* __append3(char* __buffer, _Tp __value) noexcept {
   return __itoa::__append2(__itoa::__append1(__buffer, (__value) / 100), (__value) % 100);
 }
 

libcxx/include/charconv

 #ifndef _LIBCPP_CXX03_LANG
 
 to_chars_result to_chars(char*, char*, bool, int = 10) = delete;
 from_chars_result from_chars(const char*, const char*, bool, int = 10) = delete;
 
 namespace __itoa
 {
 
-static constexpr uint64_t __pow10_64[] = {
-    UINT64_C(0),
-    UINT64_C(10),
-    UINT64_C(100),
-    UINT64_C(1000),
-    UINT64_C(10000),
-    UINT64_C(100000),
-    UINT64_C(1000000),
-    UINT64_C(10000000),
-    UINT64_C(100000000),
-    UINT64_C(1000000000),
-    UINT64_C(10000000000),
-    UINT64_C(100000000000),
-    UINT64_C(1000000000000),
-    UINT64_C(10000000000000),
-    UINT64_C(100000000000000),
-    UINT64_C(1000000000000000),
-    UINT64_C(10000000000000000),
-    UINT64_C(100000000000000000),
-    UINT64_C(1000000000000000000),
-    UINT64_C(10000000000000000000),
-};
-
-static constexpr uint32_t __pow10_32[] = {
-    UINT32_C(0),          UINT32_C(10),       UINT32_C(100),
-    UINT32_C(1000),       UINT32_C(10000),    UINT32_C(100000),
-    UINT32_C(1000000),    UINT32_C(10000000), UINT32_C(100000000),
-    UINT32_C(1000000000),
-};
 
 template <typename _Tp, typename = void>
 struct _LIBCPP_HIDDEN __traits_base
 {
     using type = uint64_t;
 
     static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
     {
         auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
-        return __t - (__v < __pow10_64[__t]) + 1;
+        return __t - (__v < __table<>::__pow10_64[__t]) + 1;
     }
 
     _LIBCPP_AVAILABILITY_TO_CHARS
     static _LIBCPP_HIDE_FROM_ABI char* __convert(_Tp __v, char* __p)
     {
         return __itoa::__base_10_u64(__v, __p);
     }
 
-    static _LIBCPP_HIDE_FROM_ABI decltype(__pow10_64)& __pow() { return __pow10_64; }
+    static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_64)& __pow() { return __table<>::__pow10_64; }
 };
 
 template <typename _Tp>
 struct _LIBCPP_HIDDEN
     __traits_base<_Tp, decltype(void(uint32_t{declval<_Tp>()}))>
 {
     using type = uint32_t;
 
     static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
     {
         auto __t = (32 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
-        return __t - (__v < __pow10_32[__t]) + 1;
+        return __t - (__v < __table<>::__pow10_32[__t]) + 1;
     }
 
     _LIBCPP_AVAILABILITY_TO_CHARS
     static _LIBCPP_HIDE_FROM_ABI char* __convert(_Tp __v, char* __p)
     {
         return __itoa::__base_10_u32(__v, __p);
     }
 
-    static _LIBCPP_HIDE_FROM_ABI decltype(__pow10_32)& __pow() { return __pow10_32; }
+    static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_32)& __pow() { return __table<>::__pow10_32; }
 };
 
 template <typename _Tp>
 inline _LIBCPP_HIDE_FROM_ABI bool
 __mul_overflowed(unsigned char __a, _Tp __b, unsigned char& __r)
 {
     auto __c = __a * __b;
     __r = __c;
if (__value < 0 && __first != __last)
         __x = __complement(__x);
     }
 
     return __to_chars_integral(__first, __last, __x, __base, false_type());
 }
 
 namespace __itoa {
 
-static constexpr char __base_2_lut[64] = {
-  '0', '0', '0', '0',
-  '0', '0', '0', '1',
-  '0', '0', '1', '0',
-  '0', '0', '1', '1',
-  '0', '1', '0', '0',
-  '0', '1', '0', '1',
-  '0', '1', '1', '0',
-  '0', '1', '1', '1',
-  '1', '0', '0', '0',
-  '1', '0', '0', '1',
-  '1', '0', '1', '0',
-  '1', '0', '1', '1',
-  '1', '1', '0', '0',
-  '1', '1', '0', '1',
-  '1', '1', '1', '0',
-  '1', '1', '1', '1'
-};
-
-static constexpr char __base_8_lut[128] = {
-  '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0', '7',
-  '1', '0', '1', '1', '1', '2', '1', '3', '1', '4', '1', '5', '1', '6', '1', '7',
-  '2', '0', '2', '1', '2', '2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7',
-  '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3', '7',
-  '4', '0', '4', '1', '4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7',
-  '5', '0', '5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7',
-  '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6', '7',
-  '7', '0', '7', '1', '7', '2', '7', '3', '7', '4', '7', '5', '7', '6', '7', '7'
-};
-
-static constexpr char __base_16_lut[512] = {
-  '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0', '7', '0', '8', '0', '9', '0', 'a', '0', 'b', '0', 'c', '0', 'd', '0', 'e', '0', 'f',
-  '1', '0', '1', '1', '1', '2', '1', '3', '1', '4', '1', '5', '1', '6', '1', '7', '1', '8', '1', '9', '1', 'a', '1', 'b', '1', 'c', '1', 'd', '1', 'e', '1', 'f',
-  '2', '0', '2', '1', '2', '2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9', '2', 'a', '2', 'b', '2', 'c', '2', 'd', '2', 'e', '2', 'f',
-  '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '3', '8', '3', '9', '3', 'a', '3', 'b', '3', 'c', '3', 'd', '3', 'e', '3', 'f',
-  '4', '0', '4', '1', '4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '4', 'a', '4', 'b', '4', 'c', '4', 'd', '4', 'e', '4', 'f',
-  '5', '0', '5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9', '5', 'a', '5', 'b', '5', 'c', '5', 'd', '5', 'e', '5', 'f',
-  '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6', '7', '6', '8', '6', '9', '6', 'a', '6', 'b', '6', 'c', '6', 'd', '6', 'e', '6', 'f',
-  '7', '0', '7', '1', '7', '2', '7', '3', '7', '4', '7', '5', '7', '6', '7', '7', '7', '8', '7', '9', '7', 'a', '7', 'b', '7', 'c', '7', 'd', '7', 'e', '7', 'f',
-  '8', '0', '8', '1', '8', '2', '8', '3', '8', '4', '8', '5', '8', '6', '8', '7', '8', '8', '8', '9', '8', 'a', '8', 'b', '8', 'c', '8', 'd', '8', 'e', '8', 'f',
-  '9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9', '5', '9', '6', '9', '7', '9', '8', '9', '9', '9', 'a', '9', 'b', '9', 'c', '9', 'd', '9', 'e', '9', 'f',
-  'a', '0', 'a', '1', 'a', '2', 'a', '3', 'a', '4', 'a', '5', 'a', '6', 'a', '7', 'a', '8', 'a', '9', 'a', 'a', 'a', 'b', 'a', 'c', 'a', 'd', 'a', 'e', 'a', 'f',
-  'b', '0', 'b', '1', 'b', '2', 'b', '3', 'b', '4', 'b', '5', 'b', '6', 'b', '7', 'b', '8', 'b', '9', 'b', 'a', 'b', 'b', 'b', 'c', 'b', 'd', 'b', 'e', 'b', 'f',
-  'c', '0', 'c', '1', 'c', '2', 'c', '3', 'c', '4', 'c', '5', 'c', '6', 'c', '7', 'c', '8', 'c', '9', 'c', 'a', 'c', 'b', 'c', 'c', 'c', 'd', 'c', 'e', 'c', 'f',
-  'd', '0', 'd', '1', 'd', '2', 'd', '3', 'd', '4', 'd', '5', 'd', '6', 'd', '7', 'd', '8', 'd', '9', 'd', 'a', 'd', 'b', 'd', 'c', 'd', 'd', 'd', 'e', 'd', 'f',
-  'e', '0', 'e', '1', 'e', '2', 'e', '3', 'e', '4', 'e', '5', 'e', '6', 'e', '7', 'e', '8', 'e', '9', 'e', 'a', 'e', 'b', 'e', 'c', 'e', 'd', 'e', 'e', 'e', 'f',
-  'f', '0', 'f', '1', 'f', '2', 'f', '3', 'f', '4', 'f', '5', 'f', '6', 'f', '7', 'f', '8', 'f', '9', 'f', 'a', 'f', 'b', 'f', 'c', 'f', 'd', 'f', 'e', 'f', 'f'
-};
-
 template <unsigned _Base>
 struct _LIBCPP_HIDDEN __integral;
 
 template <>
 struct _LIBCPP_HIDDEN __integral<2> {
   template <typename _Tp>
   _LIBCPP_HIDE_FROM_ABI static constexpr int __width(_Tp __value) noexcept {
     // If value == 0 still need one digit. If the value != this has no
_LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
 
     __last = __first + __n;
     char* __p = __last;
     const unsigned __divisor = 16;
     while (__value > __divisor) {
       unsigned __c = __value % __divisor;
       __value /= __divisor;
       __p -= 4;
-      std::memcpy(__p, &__base_2_lut[4 * __c], 4);
+      std::memcpy(__p, &__table<>::__base_2_lut[4 * __c], 4);
     }
     do {
       unsigned __c = __value % 2;
       __value /= 2;
       *--__p = "01"[__c];
     } while (__value != 0);
     return {__last, errc(0)};
   }
_LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
 
     __last = __first + __n;
     char* __p = __last;
     unsigned __divisor = 64;
     while (__value > __divisor) {
       unsigned __c = __value % __divisor;
       __value /= __divisor;
       __p -= 2;
-      std::memcpy(__p, &__base_8_lut[2 * __c], 2);
+      std::memcpy(__p, &__table<>::__base_8_lut[2 * __c], 2);
     }
     do {
       unsigned __c = __value % 8;
       __value /= 8;
       *--__p = "01234567"[__c];
     } while (__value != 0);
     return {__last, errc(0)};
   }
_LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
 
     __last = __first + __n;
     char* __p = __last;
     unsigned __divisor = 256;
     while (__value > __divisor) {
       unsigned __c = __value % __divisor;
       __value /= __divisor;
       __p -= 2;
-      std::memcpy(__p, &__base_16_lut[2 * __c], 2);
+      std::memcpy(__p, &__table<>::__base_16_lut[2 * __c], 2);
     }
     if (__first != __last)
       do {
         unsigned __c = __value % 16;
         __value /= 16;
         *--__p = "0123456789abcdef"[__c];
       } while (__value != 0);
     return {__last, errc(0)};

libcxx/src/include/ryu/digit_table.h

 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // A table of all two-digit numbers. This is used to speed up decimal digit
 // generation by copying pairs of digits into the final output.
 //
 // In order to minimize the diff in the Ryu code between MSVC STL and libc++
 // the code uses the name __DIGIT_TABLE. In order to avoid code duplication it
 // reuses the table already available in libc++.
-inline constexpr auto& __DIGIT_TABLE = __itoa::__digits_base_10<>::__value;
+inline constexpr auto& __DIGIT_TABLE = __itoa::__table<>::__digits_base_10;
 
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_SRC_INCLUDE_RYU_DIGIT_TABLE_H