[Bug c++/113141] New: ICE on conversion to reference in aggregate initialization

[Bug c++/113141] New: ICE on conversion to reference in aggregate initialization

[de34 at live dot cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

            Bug ID: 113141
           Summary: ICE on conversion to reference in aggregate
                    initialization
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Keywords: ice-checking, ice-on-invalid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: de34 at live dot cn
  Target Milestone: ---

The following program triggers ICE since GCC 13
(https://godbolt.org/z/PaqWsG9s6):

```
int global_x{};

struct ConvToRef {
    operator int&() { return global_x; }
};

struct Foo { int& r; };

int main()
{
    Foo bar{ { ConvToRef{} } };
}
```

Clang considers this ill-formed and emits "non-const lvalue reference to type
'int' cannot bind to an initializer list temporary".

If the type of r is changed to const int&, the program correctly compiles with
GCC.

[Bug c++/113141] ICE on conversion to reference in aggregate initialization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |accelerator0099 at gmail dot com

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 113142 has been marked as a duplicate of this bug. ***

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=105766,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=106201,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=94894
   Target Milestone|---                         |13.3
           Keywords|ice-checking                |
   Last reconfirmed|                            |2023-12-26
             Status|UNCONFIRMED                 |NEW
            Summary|ICE on conversion to        |[13/14 Regression] ICE on
                   |reference in aggregate      |conversion to reference in
                   |initialization              |aggregate initialization

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.


I suspect this will bisect to r13-1755-g68f37670eff0b872 .

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
             Status|NEW                         |ASSIGNED
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> Confirmed.
> 
> 
> I suspect this will bisect to r13-1755-g68f37670eff0b872 .
Yes, thus mine..

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Sergei Trofimovich <slyfox at gcc dot gnu.org> changed:

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

--- Comment #4 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Noticed a similar ICE in openmvs-2.2.0 against gcc-13/gcc-14. I reduced it with
cvise into something invalid:

  $ cat SceneDensify.cpp.cpp
  class Matrix struct TPoint3 {
    typedef Matrix EVec;
    operator const EVec();
    void Init() {
      TPoint3 X;
      (EVec &)X;
    }
  };

  $ g++ -c SceneDensify.cpp.cpp -o bug.o
  SceneDensify.cpp.cpp: In member function 'void TPoint3::Init()':
  SceneDensify.cpp.cpp:6:13: internal compiler error: in reference_binding, at
cp/call.cc:2020
      6 |     (EVec &)X;
        |             ^

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Patrick Palka <ppalka at gcc dot gnu.org> changed:

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

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Sergei Trofimovich from comment #4)
> Noticed a similar ICE in openmvs-2.2.0 against gcc-13/gcc-14. I reduced it
> with cvise into something invalid:

Interesting, this can be turned into a ice-on-valid testcase:

struct Matrix { };

struct TPoint3 { operator const Matrix(); };

int main() {
  TPoint3 X;
  Matrix& m = (Matrix &)X;
}

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
                 CC|                            |law at gcc dot gnu.org

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org
           Priority|P1                          |P2

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 13.{1,2} has been released with this bug, so P2.

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note I noticed the testcase in PR 90390 ICEs starting in GCC 13 and it seems
similar to the testcase in comment #0 here.

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cvoica at gmail dot com

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 114410 has been marked as a duplicate of this bug. ***

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

--- Comment #9 from Patrick Palka <ppalka at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:d435571b54b02946c97b5b24f20e5a7058fd96a1

commit r14-9946-gd435571b54b02946c97b5b24f20e5a7058fd96a1
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Apr 12 13:24:44 2024 -0400

    c++: reference list-init, conversion fn [PR113141]

    The original testcase in PR113141 is an instance of CWG1996; the standard
    fails to consider conversion functions when initializing a reference
    directly from an initializer-list of one element, but then does consider
    them when initializing a temporary.  I have a proposed fix for this defect,
    which is implemented here.

            DR 1996
            PR c++/113141

    gcc/cp/ChangeLog:

            * call.cc (reference_binding): Check direct binding from
            a single-element list.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/initlist-ref1.C: New test.
            * g++.dg/cpp0x/initlist-ref2.C: New test.
            * g++.dg/cpp0x/initlist-ref3.C: New test.

    Co-authored-by: Patrick Palka <ppalka@redhat.com>

[Bug c++/113141] [13/14 Regression] ICE on conversion to reference in aggregate initialization

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

--- Comment #10 from Patrick Palka <ppalka at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:df7bfdb7dbf2d46aa5768a0280d4dcfcc868b7f9

commit r14-9947-df7bfdb7dbf2d46aa5768a0280d4dcfcc868b7f9
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Apr 10 15:12:26 2024 -0400

    c++: reference cast, conversion fn [PR113141]

    The second testcase in 113141 is a separate issue: we first decide that the
    conversion is ill-formed, but then when recalculating the special c_cast_p
    handling makes us think it's OK.  We don't want that, it should continue to
    fall back to the reinterpret_cast interpretation.  And while we're here,
    let's warn that we're not using the conversion function.

    Note that the standard seems to say that in this case we should
    treat (Matrix &) as const_cast<Matrix &>(static_cast<const Matrix &>(X)),
    which would use the conversion operator, but that doesn't match existing
    practice, so let's resolve that another day.  I've raised this issue with
    CWG; at the moment I lean toward never binding a temporary in a C-style
cast
    to reference type, which would also be a change from existing practice.

            PR c++/113141

    gcc/c-family/ChangeLog:

            * c.opt: Add -Wcast-user-defined.

    gcc/ChangeLog:

            * doc/invoke.texi: Document -Wcast-user-defined.

    gcc/cp/ChangeLog:

            * call.cc (reference_binding): For an invalid cast, warn and don't
            recalculate.

    gcc/testsuite/ChangeLog:

            * g++.dg/conversion/ref12.C: New test.

    Co-authored-by: Patrick Palka <ppalka@redhat.com>

[Bug c++/113141] [13 Regression] ICE on conversion to reference in aggregate initialization

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:c70abea054fe0021b7b2c2e07996afaadc17a07b

commit r13-8670-gc70abea054fe0021b7b2c2e07996afaadc17a07b
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed May 1 18:16:08 2024 -0400

    c++: problematic assert in reference_binding [PR113141]

    r14-9946 / r14-9947 fixed this PR properly for GCC 14.

    For GCC 13, let's just remove the problematic assert.

            PR c++/113141

    gcc/cp/ChangeLog:

            * call.cc (reference_binding): Remove badness criteria sanity
            check in the recursive case.

    gcc/testsuite/ChangeLog:

            * g++.dg/conversion/ref12.C: New test.
            * g++.dg/cpp0x/initlist-ref1.C: new test.

[Bug c++/113141] [13 Regression] ICE on conversion to reference in aggregate initialization

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113141

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #12 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for 13.3/14.