[Bug c/70436] [4.9/5/6 Regression] -Wparentheses missing ambiguous else warning

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70436

--- Comment #11 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Should non-standard constructs be considered in this PR? I noticed that we also
don't warn on

  if (a)
  #pragma GCC ivdep
     while (1)
       if (b)
         bar ();
  else
    baz ();

and

  if (a)
    _Cilk_for (int i = 0; i < 10; i++)
      if (b)
        bar ();
  else
    baz ();

and probably other such constructs.