Author: Ilya Bobyr <ilya.bobyr@gmail.com>
Date:   Mon Sep 17 09:44:50 2012 -0700

    [B] Boost.PropertyTree: Correctly read UTF-8
    
    Boost.PropertyTree has a fix in version 1.45 to write narrow characters, in
    case char is signed, with highest bit set correctly.  This this a similar
    fix for the read side.

--- a/boost/property_tree/detail/json_parser_read.hpp
+++ b/boost/property_tree/detail/json_parser_read.hpp
@@ -145,7 +145,8 @@ namespace boost { namespace property_tree { namespace json_parser
             a_unicode(context &c): c(c) { }
             void operator()(unsigned long u) const
             {
-                u = (std::min)(u, static_cast<unsigned long>((std::numeric_limits<Ch>::max)()));
+                typedef typename make_unsigned<Ch>::type UCh;
+                u = (std::min)(u, static_cast<unsigned long>((std::numeric_limits<UCh>::max)()));
                 c.string += Ch(u);
             }
         };