Diagnostics for an unknown pragma?

[BigMan]

Should a compiler (according to the C++ standard) issue a warning (or
other kind of diagnostic message) when it encounters an unknown pragma
directive?

 

[Ken Human]

Should a compiler (according to the C++ standard) issue a warning (or
other kind of diagnostic message) when it encounters an unknown pragma
directive?

Unknown pragmas are ignored. The compiler can issue a warning if it
wants to, but it doesn't have to.