[Bug c++/102490] Erroneous optimization of default constexpr operator== of struct with bitfields

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102490

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
                 CC|                            |jakub at gcc dot gnu.org
   Last reconfirmed|                            |2021-09-27
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Before r10-4397-gb7689b962dd6536bbb2567bfdec52e35109af7ab , this has been
rejected with:
pr102490.C:5:48: error: ‘constexpr bool A::operator==(const A&) const’ cannot
be defaulted
    5 |   constexpr bool operator== (const A&) const = default;
      |                                                ^~~~~~~
pr102490.C:5:18: warning: inline function ‘constexpr bool A::operator==(const
A&) const’ used but never defined
    5 |   constexpr bool operator== (const A&) const = default;
      |                  ^~~~~~~~
but since then it emits:
pr102490.C: In member function ‘constexpr bool A::operator==(const A&) const’:
pr102490.C:5:18: error: type mismatch in ‘component_ref’
    5 |   constexpr bool operator== (const A&) const = default;
      |                  ^~~~~~~~
unsigned char

<unnamed-unsigned:1>

_1 = this->foo;
pr102490.C:5:18: error: type mismatch in ‘component_ref’
unsigned char

<unnamed-unsigned:1>

_2 = D.2080->foo;
pr102490.C:5:18: error: type mismatch in ‘component_ref’
unsigned char

<unnamed-unsigned:1>

_3 = this->bar;
pr102490.C:5:18: error: type mismatch in ‘component_ref’
unsigned char

<unnamed-unsigned:1>

_4 = D.2080->bar;
pr102490.C:5:18: internal compiler error: ‘verify_gimple’ failed
at -O0 or miscompiles it at -O1.