[Bug libstdc++/97001] API documentation should mention the minimum dialect

[giecrilj at stegny dot 2a.pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97001

--- Comment #3 from Christopher Yeleighton <giecrilj at stegny dot 2a.pl> ---
The problem with a module-level @since is that std:: symbols are easiest to
locate in the std namespace (which provides a huge index of everything).  Items
that are undocumented (there is a lot of them) in the namespace index are not
attributed to any module and the definition line is not available for them
either, so the reader needs a priori knowledge of which symbols belong to which
module.  While it is possible to guess the matching module with some
experience, just adding dummy documentation to those symbols (as a few of other
symbols have) would help navigating the API (also because the definition
sometimes is readable enough to be used instead of documentation).  Of course,
the fact that Doxygen bugs prevent some of the symbols from appearing in the
corresponding modules only adds to the general feeling of helplessness.