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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/111771] Incorrect "is used uninitialized" warning, as if
 zero-initialization didn't propagate through user-provided default
 constructors
Date: Thu, 12 Oct 2023 07:29:33 +0000
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X-Bugzilla-Type: changed
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X-Bugzilla-Component: c++
X-Bugzilla-Version: 13.2.0
X-Bugzilla-Keywords: diagnostic, wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111771

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-10-12
           Keywords|                            |diagnostic, wrong-code
             Status|UNCONFIRMED                 |NEW
                 CC|                            |jason at gcc dot gnu.org
      Known to fail|                            |13.2.1, 7.5.0

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have

int main ()
{
  int D.2848;

  {
    struct B b;

    try
      {
        b.D.2778.x =3D 0;
        B::B (&b);
        D.2848 =3D b.D.2778.x;
        return D.2848;

but:

void B::B (struct B * const this)
{
  _1 =3D &this->D.2778;
  A::A (_1);
}


void A::A (struct A * const this)
{
  *this =3D {CLOBBER};

so A::A invoked by B::B invalidates the initialized storage.  Maybe a
"different" B::B should have been called (one not invoking A::A?).=