[Bug middle-end/104076] bogus -Wdangling-pointer on a conditional

[msebor at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104076

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
Looking at the IL before r12-6694 I'm not sure I see what could be done to keep
the warning from triggering but maybe someone has an idea for a solution I'm
not seeing, in case this comes back with a different test case.

struct S2 f2 (bool b)
{
  const struct S1 D.2507[1];
  ...

  <bb 2> :
  cleanup.1_26 = 0;
  cleanup.2_27 = 0;
  if (b_28(D) != 0)
    goto <bb 3>; [INV]
  else
    goto <bb 4>; [INV]

  <bb 3> :
  f1 ();
  goto <bb 6>; [INV]

  <bb 4> :
  _29 = &D.2507;                        <<< &D.2507
  _30 = _29;
  _31 = 0;
  cleanup.1_32 = 1;
  S1::S1 (_30, 0);

  <bb 5> :
  _35 = _30 + 1;
  _36 = _31 + -1;
  retval.0_37 = _29;
  _38 = 0;
  cleanup.2_39 = 1;
  D.2529.array = &D.2507;
  D.2529.nelts = 1;
  S2::S2 (&D.2525, D.2529);

  <bb 6> :
  # _7 = PHI <_29(5), _44(D)(3)>        <<< _7 == _29(5) == &D.2507 or
undefined
  # _9 = PHI <_38(5), _45(D)(3)>
  # cleanup.1_13 = PHI <cleanup.1_32(5), cleanup.1_26(3)>
  # cleanup.2_15 = PHI <cleanup.2_39(5), cleanup.2_27(3)>
  if (cleanup.2_15 != 0)
    goto <bb 7>; [INV]
  else
    goto <bb 10>; [INV]

  <bb 7> :
  _46 = &D.2507 + 1;

  <bb 8> :
  # _5 = PHI <_46(7), _47(9)>
  if (&D.2507 == _5)
    goto <bb 10>; [INV]
  else
    goto <bb 9>; [INV]

  <bb 9> :
  _47 = _5 + 18446744073709551615;
  S1::~S1 (_47);
  goto <bb 8>; [INV]

  <bb 10> :
  D.2507 ={v} {CLOBBER};                <<< D.2507 clobbered
  if (cleanup.1_13 != 0)
    goto <bb 11>; [INV]
  else
    goto <bb 15>; [INV]

  <bb 11> :
  if (_7 != 0B)
    goto <bb 12>; [INV]
  else
    goto <bb 15>; [INV]

  <bb 12> :
  _1 = -_9;
  _2 = (sizetype) _1;
  _50 = _7 + _2;

  <bb 13> :
  # _11 = PHI <_50(12), _51(14)>        <<< _11 points to &D.2507
  if (_11 == _7)                        <<< -Wdangling-pointer
    goto <bb 15>; [INV]
  else
    goto <bb 14>; [INV]

  <bb 14> :
  _51 = _11 + 18446744073709551615;     <<< _51
  S1::~S1 (_51);
  goto <bb 13>; [INV]

  <bb 15> :
  return D.2525;
  ...
}


cc1plus.r12-6693: all warnings being treated as errors