hack around some linker issue in C++14

Author: AlexGuteniev

stl/inc/xcharconv_ryu_tables.h

@@ -56,6 +56,10 @@ _STD_BEGIN
 
 // vvvvvvvvvv DERIVED FROM digit_table.h vvvvvvvvvv
 
+#if !_HAS_CXX17
+namespace { // work around Clang link issues
+#endif // !_HAS_CXX17
+
 // 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.
 template <class _CharT> constexpr _CharT __DIGIT_TABLE[] = {_CharT{}};
@@ -86,6 +90,10 @@ template <> _INLINE_VAR constexpr wchar_t __DIGIT_TABLE<wchar_t>[200] = {
   L'9',L'0',L'9',L'1',L'9',L'2',L'9',L'3',L'9',L'4',L'9',L'5',L'9',L'6',L'9',L'7',L'9',L'8',L'9',L'9'
 };
 
+#if !_HAS_CXX17
+} // unnamed namespace
+#endif // !_HAS_CXX17
+
 // ^^^^^^^^^^ DERIVED FROM digit_table.h ^^^^^^^^^^
 
 // vvvvvvvvvv DERIVED FROM d2s_full_table.h vvvvvvvvvv