From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id E335B3858D33; Thu,  4 May 2023 14:21:53 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E335B3858D33
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1683210113;
	bh=rqtrChBmKcY3G4ivpA4whNJjlS7shqa4x8TQGzkwdAI=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=AT+m/cAwboHC0W55Q62UjuNeeK9YCUlyb49Jib9ULpWQ/rPsczrIJl1rM045x9VFu
	 PKS7ZfwkfRqUueAd0JF+60h9IX6S6m5n0al/GBanuEFggLxnKG3rCIKZEBdlFumIOY
	 YVg2tlXZ4BHce71AffbISGhD7uE9X+TM+IIZe4Eo=
From: "marxin at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109732] [14 regression] gcc miscompiles
 iterator comparison on nlohmann_json since r14-204-gf1f5cbaa3f716f
Date: Thu, 04 May 2023 14:21:53 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: marxin at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: pinskia at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 14.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109732-4-edut8MPcQ7@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109732-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109732-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109732

--- Comment #9 from Martin Li=C5=A1ka <marxin at gcc dot gnu.org> ---
I've got a C++ reduced test-case:

$ cat x.ii
template <typename> struct is_same;
template <bool, typename _Tp> using enable_if_t =3D _Tp;
template <typename _Iterator> struct reverse_iterator {
  _Iterator current;
  typedef _Iterator iterator_type;
  reverse_iterator(iterator_type __x) : current(__x) {}
  iterator_type base() { return current; }
};
template <typename _Iterator>
bool operator=3D=3D(reverse_iterator<_Iterator> __x,
                reverse_iterator<_Iterator> __y) {
  return __x.base() =3D=3D __y.base();
}
struct __normal_iterator {
  int _M_current;
};
template <typename> struct __new_allocator;
template <typename> struct allocator_traits;
template <typename _Tp> struct allocator_traits<__new_allocator<_Tp>> {
  using const_pointer =3D _Tp *;
};
template <typename> struct vector {
  typedef __normal_iterator iterator;
};
namespace {
enum value_t { null, object, array, string };
template <template <typename, typename...> class =3D vector,
          template <typename> class =3D __new_allocator>
class basic_json;
struct external_constructor {
  template <
      typename BasicJsonType, typename CompatibleStringType,
      enable_if_t<is_same<typename BasicJsonType::string_t>::value, int> =
=3D 0>
  static void construct(BasicJsonType &j, CompatibleStringType) {
    j.m_type =3D string;
  }
} to_json_s;
void to_json(basic_json<> &j) { external_constructor::construct(j, to_json_=
s);
}
long begin_value;
long end_value =3D 1;
struct primitive_iterator_t {
  long m_it;
  void set_begin() { m_it =3D begin_value; }
  void set_end() { m_it =3D end_value; }
  friend bool operator=3D=3D(primitive_iterator_t, primitive_iterator_t rhs=
) {
    return rhs.m_it;
  }
};
template <typename BasicJsonType> struct internal_iterator {
  typename BasicJsonType::array_t::iterator array_iterator;
  primitive_iterator_t primitive_iterator;
};
template <typename BasicJsonType> struct iter_impl {
  using array_t =3D typename BasicJsonType::array_t;
  typedef typename BasicJsonType::const_pointer pointer;
  iter_impl(pointer object) : m_object(object) {
    switch (m_object->m_type)
    case ::object:
    case array:
      m_it.array_iterator =3D typename array_t::iterator();
  }
  void set_begin() {
    switch (m_object->m_type) {
    case object:
    case array:
      break;
    case null:
      m_it.primitive_iterator.set_end();
      break;
    default:
      m_it.primitive_iterator.set_begin();
    }
  }
  template <typename IterImpl> bool operator=3D=3D(IterImpl other) {
    return m_it.primitive_iterator =3D=3D other.m_it.primitive_iterator;
  }
  pointer m_object;
  internal_iterator<BasicJsonType> m_it;
};
template <typename Base> struct json_reverse_iterator : reverse_iterator<Ba=
se>
{
  json_reverse_iterator(Base it) : reverse_iterator<Base>(it) {}
};
template <template <typename, typename...> class ArrayType,
          template <typename> class AllocatorType>
struct basic_json {
  using const_pointer =3D
      typename allocator_traits<AllocatorType<basic_json>>::const_pointer;
  using const_iterator =3D iter_impl<basic_json>;
  using const_reverse_iterator =3D json_reverse_iterator<const_iterator>;
  using array_t =3D ArrayType<basic_json>;
  template <typename CompatibleType> basic_json(CompatibleType) {
    to_json(*this);
  }
  const_iterator cbegin() {
    const_iterator result(this);
    result.set_begin();
    return result;
  }
  const_iterator cend() {
    const_iterator result(this);
    return result;
  }
  const_reverse_iterator crbegin() { return cend(); }
  const_reverse_iterator crend() { return cbegin(); }
  value_t m_type;
};
} // namespace
int seen_failures;
__attribute__((noinline)) void sne(basic_json<>::const_reverse_iterator lhs,
                                   basic_json<>::const_reverse_iterator rhs=
) {
  bool res =3D !(lhs =3D=3D rhs);
  if (!res)
    seen_failures++;
}
basic_json main_js =3D "";

int
main() {
  basic_json js_const(main_js);
  basic_json<>::const_reverse_iterator sit =3D js_const.crbegin(),
                                       __trans_tmp_1 =3D js_const.crend();
  sne(sit, __trans_tmp_1);
  return seen_failures;
}=