From c93e5a88c7846b5f7cdf6af3aad2365f3fc7dba9 Mon Sep 17 00:00:00 2001
From: Fernando Cacciola <fernando.cacciola@gmail.com>
Date: Tue, 20 Jul 2010 18:20:40 +0000
Subject: [PATCH] Fixed extraction operator for empty optionals

[SVN r64206]
---
 include/boost/optional/optional_io.hpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/boost/optional/optional_io.hpp b/include/boost/optional/optional_io.hpp
index 85a1857..85ba7b3 100644
--- a/include/boost/optional/optional_io.hpp
+++ b/include/boost/optional/optional_io.hpp
@@ -25,7 +25,7 @@
 #  include <ostream>
 #endif  
 
-
+#include <boost/assert.hpp>
 #include "boost/optional/optional.hpp"
 #include "boost/utility/value_init.hpp"
 
@@ -72,7 +72,12 @@ operator>>(std::basic_istream<CharType, CharTrait>& in, optional<T>& v)
       v = x ;
     }
     else
+    {
+      BOOST_ASSERT(d == '-');
+      d = in.get();
+      BOOST_ASSERT(d == '-');
       v = optional<T>() ;
+    }
   }
 
   return in;