Move from rvalues eagerly to work around MSVC problem

On MSVC compiler, temporaries that are constructed during a list initialization, are sometimes destroyed even before calling the initializing constructor, instead of at the end of the containing full-expression. This is clearly non-conforming to [class.temporary]. As the impact of this bug is silently producing incorrect JSON values, move eagerly from rvalues to be safe. See https://stackoverflow.com/questions/24586411

Move from rvalues eagerly to work around MSVC problem
93bb7123 · Nikita Ofitserov · 897879bc · 93bb7123
Commit 93bb7123 authored Jul 25, 2017 by Nikita Ofitserov
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json.hpp src/json.hpp +4 -2

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--- a/src/json.hpp
+++ b/src/json.hpp
@@ -7088,9 +7088,11 @@ struct json_ref
    typedef BasicJsonType value_type;

    json_ref(value_type&&  value)
-        : value_ref_(&value)
+        : owned_value_(std::move(value))
        , is_rvalue_(true)
-    {}
+    {
+        value_ref_ = &owned_value_;
+    }

    json_ref(const value_type& value)
        : value_ref_(const_cast<value_type*>(&value))