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From: "avi at scylladb dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/105373] miscompile involving lambda coroutines and an
 object bitwise copied instead of via the copy constructor
Date: Mon, 25 Apr 2022 11:14:23 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105373

--- Comment #1 from Avi Kivity <avi at scylladb dot com> ---
I randomly looked at 023t.ssa (mainly because I recognized the acronym).

  _45 =3D frame_ptr_182(D)->__closure;
  _46 =3D _45->__this;
  frame_ptr_182(D)->D.2159984_4_7 =3D
_46->_config.memtable_to_cache_scheduling_group;
  _47 =3D &frame_ptr_182(D)->D.2159792_4_7;
  _48 =3D frame_ptr_182(D)->__closure;
  _49 =3D &_48->__old3;
  seastar::lw_shared_ptr<replica::memtable>::lw_shared_ptr (_47, _49);
  _50 =3D frame_ptr_182(D)->__closure;
  _51 =3D _50->__this;
  frame_ptr_182(D)->D.2159793_4_7.__this =3D _51;
  frame_ptr_182(D)->D.2159793_4_7.__old4 =3D frame_ptr_182(D)->D.2159792_4_=
7;
  _52 =3D frame_ptr_182(D)->__closure;
  _53 =3D _52->__newtabs;
  frame_ptr_182(D)->D.2159793_4_7.__newtabs =3D _53;
  _54 =3D &frame_ptr_182(D)->D.2159793_4_7;
  frame_ptr_182(D)->D.2160366_4_7 =3D
seastar::with_scheduling_group<replica::table::try_flush_memtable_to_sstabl=
e(replica::table::try_flush_memtable_to_sstable(seastar::lw_shared_ptr<repl=
ica::memtable>,
sstable_write_permit&&)::_ZN7replica5table29try_flush_memtable_to_sstableEN=
7seastar13lw_shared_ptrINS_8memtableEEEO20sstable_write_permit.Frame*)::<la=
mbda()>::operator()(replica::table::try_flush_memtable_to_sstable(replica::=
table::try_flush_memtable_to_sstable(seastar::lw_shared_ptr<replica::memtab=
le>,
sstable_write_permit&&)::_ZN7replica5table29try_flush_memtable_to_sstableEN=
7seastar13lw_shared_ptrINS_8memtableEEEO20sstable_write_permit.Frame*)::<la=
mbda()>
mutable::_ZZN7replica5table29try_flush_memtable_to_sstableEN7seastar13lw_sh=
ared_ptrINS_8memtableEEEO20sstable_write_permitENUlvE_clEv.Frame*)::<lambda=
()>::operator()(replica::table::try_flush_memtable_to_sstable(replica::tabl=
e::try_flush_memtable_to_sstable(seastar::lw_shared_ptr<replica::memtable>,
sstable_write_permit&&)::_ZN7replica5table29try_flush_memtable_to_sstableEN=
7seastar13lw_shared_ptrINS_8memtableEEEO20sstable_write_permit.Frame*)::<la=
mbda()>::operator()(replica::table::try_flush_memtable_to_sstable(replica::=
table::try_flush_memtable_to_sstable(seastar::lw_shared_ptr<replica::memtab=
le>,
sstable_write_permit&&)::_ZN7replica5table29try_flush_memtable_to_sstableEN=
7seastar13lw_shared_ptrINS_8memtableEEEO20sstable_write_permit.Frame*)::<la=
mbda()>
mutable::_ZZN7replica5table29try_flush_memtable_to_sstableEN7seastar13lw_sh=
ared_ptrINS_8memtableEEEO20sstable_write_permitENUlvE_clEv.Frame*)::<lambda=
()>
mutable::_ZZZN7replica5table29try_flush_memtable_to_sstableEN7seastar13lw_s=
hared_ptrINS_8memtableEEEO20sstable_write_permitENUlvE_clEvENUlvE1_clEv.Fra=
me*)::<lambda()>
> (frame_ptr_182(D)->D.2159984_4_7, _54); [return slot optimization]
  _55 =3D &frame_ptr_182(D)->D.2160366_4_7;
  frame_ptr_182(D)->Aw5_4_7 =3D seastar::operator co_await<void> (_55); [re=
turn
slot optimization]


In the line

  frame_ptr_182(D)->D.2159793_4_7.__old4 =3D frame_ptr_182(D)->D.2159792_4_=
7;


Is this not a bitwise copy, which should be instead a call to the copy
constructor?=