[Bug c++/57335] New: internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[Bug c++/57335] New: internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[chet.simpson at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

            Bug ID: 57335
           Summary: internal compiler error: in cxx_eval_bit_field_ref, at
                    cp/semantics.c:6977
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chet.simpson at gmail dot com

This error appears to be caused though the static_assert on a constexpr
containing a union.

prog.cpp: In function ‘int main()’:
prog.cpp:29:48:   in constexpr expansion of
‘BitsOrderCheck().BitsOrderCheck::IsLsbBottom()’
prog.cpp:29:58: internal compiler error: in cxx_eval_bit_field_ref, at
cp/semantics.c:6977
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
Preprocessed source stored into /home/nUBliJ/ccd38zvW.out file, please attach
this to your bugreport.



#include <stdint.h>
#include <iostream>

struct BitsOrderCheck
{
    union Data
    {
        struct Bitfield
        {
            const unsigned char   clear:7;
            const unsigned char   set:1;
        };

        const unsigned char   byte;
        const Bitfield        bits;
        constexpr Data() : byte(1) {}
    };
    constexpr BitsOrderCheck() {}
    constexpr bool IsLsbBottom() const
    {
        return 1 == data_.bits.set;
    }

    const Data    data_;
};

int main()
{
    static_assert(BitsOrderCheck().IsLsbBottom(), "blah");
    std::cout << "LSB: " << BitsOrderCheck().IsLsbBottom() << std::endl;
    return 0;
}
>From gcc-bugs-return-422622-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Mon May 20 10:42:41 2013
Return-Path: <gcc-bugs-return-422622-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 25134 invoked by alias); 20 May 2013 10:42:41 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 25106 invoked by uid 48); 20 May 2013 10:42:38 -0000
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/57336] New: [4.8/4.9 Regression] Cannot INVOKE a reference_wrapper around an abstract type
Date: Mon, 20 May 2013 10:42:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 4.8.1
X-Bugzilla-Keywords: rejects-valid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: redi at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status keywords bug_severity priority component assigned_to reporter
Message-ID: <bug-57336-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2013-05/txt/msg01295.txt.bz2
Content-length: 1041

http://gcc.gnu.org/bugzilla/show_bug.cgi?idW336

            Bug ID: 57336
           Summary: [4.8/4.9 Regression] Cannot INVOKE a reference_wrapper
                    around an abstract type
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: redi at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org

This C++11 example no longer compiles:


#include <functional>

struct ABC
{
    virtual bool operator()() const = 0;
};

struct Concrete : ABC
{
    virtual bool operator()() const { return true; }
};

Concrete c;
ABC& abc = c;

auto b = std::cref(abc)();



I think we're just missing an rvalue-ref on the function argument and in the
result_of argument in the first overload of __invoke, which is also necessary
to get the right answer when invoking function objects with ref-qualified
function call operators (something I plan to finish support for asap)

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-05-20
             Blocks|                            |55004
     Ever confirmed|0                           |1

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Note: all the other compilers I have at hand reject the snippet with an error
message about the static_assert expression not being constant (which behavior,
in case the analysis shows it's correct, would be easy to obtain with GCC too)

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler@googlemail.
                   |                            |com

--- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Paolo Carlini from comment #1)
I agree that the code should be rejected, because the created BitsOrderCheck
object initializes the member 'byte' of the union and later attempts to read
the member 'bits', thus causing the exclusion case of core constant
expressions:

"an lvalue-to-rvalue conversion (4.1) or modification (5.17, 5.2.6, 5.3.2) that
is applied to a glvalue that refers to a non-active member of a union or a
subobject thereof;"
>From gcc-bugs-return-422630-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Mon May 20 12:30:10 2013
Return-Path: <gcc-bugs-return-422630-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 22507 invoked by alias); 20 May 2013 12:30:10 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 22385 invoked by uid 48); 20 May 2013 12:30:02 -0000
From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/57038] Latest libreoffice compilation fails with enabled LTO
Date: Mon, 20 May 2013 12:30:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 4.9.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: hubicka at gcc dot gnu.org
X-Bugzilla-Status: WAITING
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_status cf_reconfirmed_on everconfirmed
Message-ID: <bug-57038-4-J3z5UGwY2Y@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-57038-4@http.gcc.gnu.org/bugzilla/>
References: <bug-57038-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2013-05/txt/msg01303.txt.bz2
Content-length: 548

http://gcc.gnu.org/bugzilla/show_bug.cgi?idW038

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2013-05-20
     Ever confirmed|0                           |1

--- Comment #21 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
I submitted the patch to fix weakrefs.
Where we are with the compilation now?

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
... but we ICE with the testcase adjusted too.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
The code in cxx_eval_bit_field_ref needs some work, doesn't handle CONSTRUCTORs
inside CONSTRUCTORs. This is a reduced testcase:

struct BitsOrderCheck
{
  struct Data
  {
    const unsigned char   set:1;
    constexpr Data() : set{1} {}
  };

  constexpr bool IsLsbBottom() const
  {
    return 1 == data_.set;
  }

  const Data    data_;
};

static_assert(BitsOrderCheck().IsLsbBottom(), "blah");

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Kai's delayed folding work ought to fix this by avoiding creating
BIT_FIELD_REFs so soon.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[ktietz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ktietz at gcc dot gnu.org

--- Comment #6 from Kai Tietz <ktietz at gcc dot gnu.org> ---
Yes, delayed folding fixes wrong-code/valid-code samples.

For invalid-code I see with delayed folding the following error-messages:

t_pr57335.C: In function 'int main()':
t_pr57335.C:29:5: error: non-constant condition for static assertion
     static_assert(BitsOrderCheck().IsLsbBottom(), "blah");
     ^
t_pr57335.C:29:47:   in constexpr expansion of
'BitsOrderCheck().BitsOrderCheck::IsLsbBottom()'
t_pr57335.C:29:5: error: accessing 'BitsOrderCheck::Data::bits' member instead
of initialized 'BitsOrderCheck::Data::byte' member in constant expression

Not sure if this is desired.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Kai Tietz from comment #6)
> t_pr57335.C:29:5: error: accessing 'BitsOrderCheck::Data::bits' member
> instead of initialized 'BitsOrderCheck::Data::byte' member in constant
> expression

Yes, that's the desired behavior for this testcase.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paolo.carlini at oracle dot com

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Good. What about the snippet in Comment #4, though? That one seems Ok to me and
meaning that cxx_eval_bit_field_ref needs some work.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

--- Comment #10 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Ah, excellent.

[Bug c++/57335] internal compiler error: in cxx_eval_bit_field_ref, at cp/semantics.c:6977

[ktietz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57335

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |ktietz at gcc dot gnu.org

--- Comment #11 from Kai Tietz <ktietz at gcc dot gnu.org> ---
Mine.