Fix empty string deserialization with API version 1

Author: kovdan01

include/msgpack/v1/adaptor/string.hpp

@@ -30,16 +30,10 @@ struct convert<std::string> {
     msgpack::object const& operator()(msgpack::object const& o, std::string& v) const {
         switch (o.type) {
         case msgpack::type::BIN:
-            if (o.via.bin.size == 0)
-                v.clear();
-            else
-                v.assign(o.via.bin.ptr, o.via.bin.size);
+            v.assign(o.via.bin.ptr, o.via.bin.size);
             break;
         case msgpack::type::STR:
-            if (o.via.str.size == 0)
-                v.clear();
-            else
-                v.assign(o.via.str.ptr, o.via.str.size);
+            v.assign(o.via.str.ptr, o.via.str.size);
             break;
         default:
             throw msgpack::type_error();

include/msgpack/v1/unpack.hpp

@@ -177,6 +177,9 @@ inline void unpack_str(unpack_user& u, const char* p, uint32_t l, msgpack::objec
         std::memcpy(tmp, p, l);
         o.via.str.ptr = tmp;
     }
+    else {
+        o.via.str.ptr = MSGPACK_NULLPTR;
+    }
     o.via.str.size = l;
 }
 
@@ -193,6 +196,9 @@ inline void unpack_bin(unpack_user& u, const char* p, uint32_t l, msgpack::objec
         std::memcpy(tmp, p, l);
         o.via.bin.ptr = tmp;
     }
+    else {
+        o.via.bin.ptr = MSGPACK_NULLPTR;
+    }
     o.via.bin.size = l;
 }