[boost] bjam question about "requires" negation

Subject: [boost] bjam question about "requires" negation
From: James E. King III (jking_at_[hidden])
Date: 2018-10-13 14:03:31

I want to run a test that should run without explicit operator conversion
capability and fail to compile with explicit operation conversion
capability, but I'm not sure how to negate the requires statement.  I'm
sure it's trivial but I found no examples.  I tried a bunch of things but
none worked.

      [ run          implicit_conversion.cpp
          : : : [ requires NO cxx11_explicit_conversion_operators ] :
implicit_conversion ]
      [ compile-fail implicit_conversion.cpp
          :     [ requires cxx11_explicit_conversion_operators ] :
explicit_conversion ]

How do I properly implement the "NO" part?

Thanks,

Jim