Hand add the fix from github.com/boostorg/system/pull/12. Note: This fix was verified by testing in release mode with clang 4.0 on Linux. It crashed before applying the P/R and passed afterwards. The pull request was applied by hand to add some new comments and do some other minor code rearrangements. Thanks to Visigoth for the P/R.

test/error_code_test.cpp

@@ -99,6 +99,9 @@ namespace
     catch (...)
       { exception_thrown = true; }            
     BOOST_TEST(exception_thrown);
+
+    //error_code should_fail(boost::throws());     // should fail at runtime
+    //boost::throws() = ec;                        // should fail at runtime
   }
 }