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From: "mohamed.selim at dxc dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/112350] New: gcc is not triggering a dangling reference
 indicating stack use after return
Date: Thu, 02 Nov 2023 15:02:07 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 13.2.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: mohamed.selim at dxc dot com
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112350

            Bug ID: 112350
           Summary: gcc is not triggering a dangling reference indicating
                    stack use after return
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mohamed.selim at dxc dot com
  Target Milestone: ---

Scenario A:
gcc is not triggering a dangling reference indicating stack use after retur=
n,
the address-sanitizer does trigger though.

"=3D=3D1=3D=3DERROR: AddressSanitizer: stack-use-after-return on"

Scenario B:
gcc triggers a warning "-Wreturn-local-addr"

The sanitizers intervenes in both scenarios as expected, while gcc warnings=
 in
not triggered in scenario A. Looks like the reference_wrapper has something=
 to
do with it.


compiler options used:
-std=3Dc++14 -Wframe-address -Wreturn-local-addr -Wall -Wextra -Wpedantic
-fsanitize=3Daddress


#include <iostream>
#include <utility>


// scenario A
const int& foo()
{
    int x =3D 234;
    std::reference_wrapper<int> s{x};

    return s.get();
}

// scenario B
const int& foo()
{
    int s =3D 234;=20=20=20
    return s;
}

int main()
{
    const auto& f_res =3D foo();
    std::cout << "result: " << f_res << "\n";

    return 0;
}=