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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rust/107633] [13 regression] Bootstrap failure due to
 -Werror=unused-parameter and -Werror=dangling-reference
Date: Fri, 11 Nov 2022 13:45:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107633

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Rainer Orth from comment #0)
> /vol/gcc/src/hg/master/rust/gcc/rust/typecheck/rust-hir-type-check-type.c=
c:
> In member function 'Rust::TyTy::BaseType*
> Rust::Resolver::TypeCheckType::resolve_segments(Rust::NodeId, Rust::HirId,
> std::vector<std::unique_ptr<Rust::HIR::TypePathSegment> >&, std::size_t,
> Rust::TyTy::BaseType*, const Rust::Analysis::NodeMapping&, Location)':
> /vol/gcc/src/hg/master/rust/gcc/rust/typecheck/rust-hir-type-check-type.c=
c:
> 465:13: error: possibly dangling reference to a temporary
> [-Werror=3Ddangling-reference]
>   465 |       auto &candidate =3D *candidates.begin ();

This should probably be:

    auto first =3D candidates.begin ();
    auto &candidate =3D *first;

so that the iterator persists as long as its value is needed.=