[Bug rust/107633] [13 regression] Bootstrap failure due to -Werror=unused-parameter and -Werror=dangling-reference

["ro at CeBiTec dot Uni-Bielefeld.DE" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107633

--- Comment #6 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
> https://gcc.gnu.org/pipermail/gcc-patches/2022-November/605800.html, if
> accepted, should help.

The patch doesn't apply cleanly to the devel/rust/master branch,
unfortunately.  Even when I adjust it manually, the build fails with

/vol/gcc/src/hg/master/rust/gcc/cp/call.cc: In function 'void
maybe_warn_dangling_reference(const_tree, tree)':
/vol/gcc/src/hg/master/rust/gcc/cp/call.cc:13547:5: error: 'std_pair_ref_ref_p'
was not declared in this scope
13547 |  || std_pair_ref_ref_p (type)))
      |     ^~~~~~~~~~~~~~~~~~

I'll leave this to the rust developers to figure out: my primary goal
was to check if the branch still builds on Solaris and has reasonable
rust test results.

Another message to the developers is to try a bootstrap build once in a
while: while non-bootstrap is certainly reasonable during development,
finding that bootstrap is broken shortly before the merge date isn't the
best idea, I believe ;-)