use Charconv library instead of embedded copy

CMakeLists.txt

@@ -85,6 +85,7 @@ function(boost_json_setup_properties target)
             Boost::align
             Boost::assert
             Boost::config
+            Boost::charconv
             Boost::container
             Boost::container_hash
             Boost::core

README.md

@@ -108,12 +108,9 @@ in order to support both little endian and big endian platforms.
 Boost.JSON has been tested with the following compilers:
 
 * clang: 3.5, 3.6, 3.7, 3.8, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
-* gcc: 4.8, 4.9, 5, 6, 7, 8, 9, 10, 11, 12
+* gcc: 5, 6, 7, 8, 9, 10, 11, 12
 * msvc: 14.0, 14.1, 14.2, 14.3
 
-**Note: support for GCC 4.8 and 4.9 is deprecated and will stop in
-Boost 1.88.0.**
-
 ### Supported JSON Text
 
 The library expects input text to be encoded using UTF-8, which is a

build.jam

@@ -13,6 +13,7 @@ using boost-pretty-printers ;
 constant boost_dependencies :
     /boost/align//boost_align
     /boost/assert//boost_assert
+    /boost/charconv//boost_charconv
     /boost/config//boost_config
     /boost/container//boost_container
     /boost/container_hash//boost_container_hash

build/Jamfile

@@ -77,6 +77,7 @@ project
       <toolset>msvc:<define>_SCL_SECURE_NO_WARNINGS
     : usage-requirements
       <library>/boost/container//boost_container/<warnings-as-errors>off
+      <library>/boost/charconv//boost_charconv/<warnings-as-errors>off
       <define>BOOST_JSON_NO_LIB=1
     : source-location ../src
     ;

doc/qbk/overview.qbk

@@ -134,12 +134,9 @@ Boost.Endian] in order to support both little endian and big endian platforms.
 Boost.JSON has been tested with the following compilers:
 
 * clang: 3.8, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
-* gcc: 4.8, 4.9, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
+* gcc: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
 * msvc: 14.0, 14.1, 14.2, 14.3
 
-[important Support for GCC 4.8 and 4.9 is deprecated and will stop in
-Boost 1.88.0.]
-
 [heading Supported JSON Text]
 
 The library expects input text to be encoded using UTF-8, which is a

include/boost/json/basic_parser_impl.hpp

@@ -16,7 +16,7 @@
 #include <boost/json/basic_parser.hpp>
 #include <boost/json/error.hpp>
 #include <boost/json/detail/buffer.hpp>
-#include <boost/json/detail/charconv/from_chars.hpp>
+#include <boost/charconv/from_chars.hpp>
 #include <boost/json/detail/sse2.hpp>
 #include <boost/mp11/algorithm.hpp>
 #include <boost/mp11/integral.hpp>
@@ -2735,11 +2735,11 @@ parse_number(const char* p,
             data = num_buf_.append( begin, size );
             full_size = num_buf_.size();
         }
-        auto const err = detail::charconv::from_chars(
+        auto const result = charconv::from_chars_erange(
             data, data + full_size, d );
-        BOOST_ASSERT( err.ec != std::errc::invalid_argument );
-        BOOST_ASSERT( err.ptr == data + full_size );
-        (void)err;
+        BOOST_ASSERT( result.ec != std::errc::invalid_argument );
+        BOOST_ASSERT( result.ptr == data + full_size );
+        (void)result;
     }
     else BOOST_IF_CONSTEXPR( no_parsing )
         d = 0;