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.

include/boost/system/error_code.hpp

@@ -542,8 +542,9 @@ namespace boost
     //  "throws" function in namespace boost rather than namespace boost::system.
 
   }  // namespace system
-
-  namespace detail { inline system::error_code * throws() { return 0; } }
+                                                               
+  namespace detail
+  {
     //  Misuse of the error_code object is turned into a noisy failure by
     //  poisoning the reference. This particular implementation doesn't
     //  produce warnings or errors from popular compilers, is very efficient
@@ -551,8 +552,17 @@ namespace boost
     //  from order of initialization problems. In practice, it also seems
     //  cause user function error handling implementation errors to be detected
     //  very early in the development cycle.
+    inline system::error_code* throws()
+    {
+      // See github.com/boostorg/system/pull/12 by visigoth for why the return
+      // is poisoned with (1) rather than (0). A test, test_throws_usage(), has
+      // been added to error_code_test.cpp, and as visigoth mentioned it fails
+      // on clang for release builds with a return of 0 but works fine with (1).
+      return reinterpret_cast<system::error_code*>(1);
+    }
+  }
 
-  inline system::error_code & throws()
+  inline system::error_code& throws()
     { return *detail::throws(); }
 
   namespace system

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
   }
 }