[Bug c++/68965] [5/6 Regression] `-Wunused-parameter` is reported in variadic lambda or function using sizeof...(xs)

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68965

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |mpolacek at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Ok I think I see what the problem is.  Before r230629, in
tsubst_pack_expansion, we'd go the convert_from_reference way even for
"sizeof...".  And convert_from_reference entails mark_exp_read call.  But since
that rev, we optimize and skip the convert_from_reference call thus even the
mark_exp_read call.

Shouldn't be terribly hard to fix, thus mine.