[Bug c++/90184] confusing diagnostic "attribute using prefix"

[roland.illig at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90184

--- Comment #2 from Roland Illig <roland.illig at gmx dot de> ---
(In reply to Jonathan Wakely from comment #1)
> But is it confusing in context when the diagnostic points to a piece of code
> saying [[using gnu: noinline]] ?

Yes, it is. I just had a look at gen-attrs-66.C, and even when seeing the
corresponding source code, I am still confused by the highly ambiguous grammar.

My try for a better wording:

the %<using%> prefix for attributes is only available ...

This follows the GCC Guidelines for Diagnostics more closely, which say that
diagnostics should be complete sentences.