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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/104076] New: bogus -Wdangling-pointer on a conditional
Date: Mon, 17 Jan 2022 22:10:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104076

            Bug ID: 104076
           Summary: bogus -Wdangling-pointer on a conditional
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

As reported in
https://gcc.gnu.org/pipermail/gcc-patches/2022-January/588620.html, the new
-Wdangling-pointer issues a false positive for the following test case:

$ cat t.C && g++ -S -Wall t.C
#include <initializer_list>

struct S1
{
  S1 (int);
  ~S1 ();
};

struct S2 { S2 (std::initializer_list<S1>); };

S2 f1();

S2 f2(bool b)
{
  return b ? f1() : S2{0};
}

t.C: In function =E2=80=98S2 f2(bool)=E2=80=99:
t.C:16:1: warning: dangling pointer to an unnamed temporary may be used
[-Wdangling-pointer=3D]
   16 | }
      | ^
t.C:15:25: note: unnamed temporary defined here
   15 |   return b ? f1() : S2{0};
      |                         ^
t.C:16:1: warning: dangling pointer to an unnamed temporary may be used
[-Wdangling-pointer=3D]
   16 | }
      | ^
t.C:15:25: note: unnamed temporary defined here
   15 |   return b ? f1() : S2{0};
      |                         ^=