[Bug testsuite/114384] Use of `target c++98/c++11/c++20` etc. is not documented

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114384

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #2)
> (In reply to Andrew Pinski from comment #0)
> > and even how to describe the above
> > would be very useful. Do we need 3 testcases, one for pre C++11, one for
> > C++11/C++14 and one for C++17+ ?
> 
> No, you could use { target { c++11 && c++14_down } }

And this should be equivalent:  { target c++11_only c++14_only }