From: Jason Merrill <jason@redhat.com>
To: Marek Polacek <polacek@redhat.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] c++: suppress -Wdangling-reference for std::span [PR107532]
Date: Mon, 13 Mar 2023 11:18:09 -0400 [thread overview]
Message-ID: <046be9c9-c78c-fddb-f2e9-915901029752@redhat.com> (raw)
In-Reply-To: <20230310190741.168444-1-polacek@redhat.com>
On 3/10/23 14:07, Marek Polacek wrote:
> std::span is a view and therefore should be treated as a reference
> wrapper class for the purposes of -Wdangling-reference. I'm not sure
> there's a pattern that we could check for.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
> PR c++/107532
>
> gcc/cp/ChangeLog:
>
> * call.cc (reference_like_class_p): Check for std::span.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/warn/Wdangling-reference10.C: New test.
> ---
> gcc/cp/call.cc | 1 +
> gcc/testsuite/g++.dg/warn/Wdangling-reference10.C | 12 ++++++++++++
> 2 files changed, 13 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
>
> diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
> index 3dfa12a0733..c01e7b82457 100644
> --- a/gcc/cp/call.cc
> +++ b/gcc/cp/call.cc
> @@ -13800,6 +13800,7 @@ reference_like_class_p (tree ctype)
> tree name = DECL_NAME (tdecl);
> return (name
> && (id_equal (name, "reference_wrapper")
> + || id_equal (name, "span")
> || id_equal (name, "ref_view")));
> }
> for (tree fields = TYPE_FIELDS (ctype);
> diff --git a/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
> new file mode 100644
> index 00000000000..733fb8cce63
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
> @@ -0,0 +1,12 @@
> +// PR c++/107532
> +// { dg-do compile { target c++20 } }
> +// { dg-options "-Wdangling-reference" }
> +
> +#include <span>
> +#include <vector>
> +
> +void f(const std::vector<int>& v)
> +{
> + const int& r = std::span<const int>(v)[0]; // { dg-bogus "dangling reference" }
> + (void) r;
> +}
>
> base-commit: 20d790aa3ea5b0d240032cab997b8e0938cac62c
prev parent reply other threads:[~2023-03-13 15:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-10 19:07 Marek Polacek
2023-03-13 15:18 ` Jason Merrill [this message]
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