-Winvalid-constexpr reports as a compile error - is this intentional?

I have (inadvertently) enabled Clang 6.0.0 warning

   -Winvalid-constexpr

This revealed a pre-existing 'feature' in Boost.System error_code.hpp and signalled this as a compile error.

Since this is only advertised as a warning, I was surprised (and slightly inconvenienced) to get an error rather than a warning.

If I suppress the warning (-Wno-invalid-constexpr for example), the code compiles, links and works as expected.

Is signalling this warning as a compile error intentional?

Thank you.

Paul

Hi Paul,