[Bug middle-end/102276] -ftrivial-auto-var-init fails to initialize a variable, causes a spurious warning

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102276

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |qing.zhao at oracle dot com,
                   |                            |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2021-09-13

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Both cases jump past the initialization - for C++ this would be a invalid
testcase I guess while for C we'd warn if the 'x' were initialized.

I'm not sure if it is reasonably possible to "fix" these cases.

Confirmed for the spurious warning, it is emitted by gimplification on

  switch (0) <default: <D.1982>>
  {
    int x;

    try
      {
        _1 = .DEFERRED_INIT (4, 1, 0);
        x = _1;
        __builtin_clear_padding (&x, 0B, 1);
        <D.1982>:
        D.1989 = g (&x);
        return D.1989;
      }
    finally
      {
        x = {CLOBBER};
      }
  }