warnings on clang-17.0.2

[andrewcorrigan]

My last PR, 312, fixed an error I was encountering using MSVC. Unfortunately, this is now triggering warnings on Clang. Would it make sense to add an #if guard and redo my last PR so that we only include the space for compilers that actually require it? This way, MSVC continues to compile and hopefully we could silence warnings from compilers that consider this deprecated?

/third_party/obake/mppp/include/mp++/detail/integer_literals.hpp:410:1: warning: identifier '_z1' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  410 | MPPP_DECLARE_INTEGRAL_UDL(1)
      | ^

[bluescarni]

Would it be possible instead to suppress the specific warning with a pragma or compiler flag for MSVC?

#ifdef-fing would certainly work, but I would like to avoid code repetition if possible.