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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/109770] New: wrong(?) devirtualization
Date: Mon, 08 May 2023 13:30:29 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: ipa
X-Bugzilla-Version: 13.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109770

            Bug ID: 109770
           Summary: wrong(?) devirtualization
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

#include <new>

struct Base
{
  virtual ~Base() {}
};
struct A : Base
{
  virtual ~A() {}
};
struct B : Base
{
  [[gnu::noinline]] B() { new (this) A; }
  virtual ~B() { __builtin_abort (); }
};
int main()
{
  Base *p =3D new B;
  delete p;
}

aborts when compiled with -O2 (with devirtualization enabled).  Neither
GCC nor clang diagnose the placement new in B::B() (but it looks fishy).=