[Bug c++/102050] New: Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[Bug c++/102050] New: Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102050

            Bug ID: 102050
           Summary: Nonempty list-initialization rejects constructor with
                    defaulted std::initializer_list
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/5PGza1o8e.
```C++
#include <initializer_list>
struct S { S( std::initializer_list<int> = {} ) {} };
int main() { S{0}; }
```
```
<source>: In function 'int main()':
<source>:3:17: error: no matching function for call to 'S::S(<brace-enclosed
initializer list>)'
    3 | int main() { S{0}; }
      |                 ^
<source>:2:12: note: candidate: 'S::S(std::initializer_list<int>)'
    2 | struct S { S( std::initializer_list<int> = {} ) {} };
      |            ^
<source>:2:15: note:   no known conversion for argument 1 from 'int' to
'std::initializer_list<int>'
    2 | struct S { S( std::initializer_list<int> = {} ) {} };
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:2:8: note: candidate: 'constexpr S::S(const S&)'
    2 | struct S { S( std::initializer_list<int> = {} ) {} };
      |        ^
<source>:2:8: note:   no known conversion for argument 1 from 'int' to 'const
S&'
<source>:2:8: note: candidate: 'constexpr S::S(S&&)'
<source>:2:8: note:   no known conversion for argument 1 from 'int' to 'S&&'
Compiler returned: 1
```

This came up at https://cpplang.slack.com/archives/C2SLQATS9/p1629835850325200.

[Bug c++/102050] Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102050

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Target Milestone|---                         |12.0
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
                 CC|                            |ppalka at gcc dot gnu.org
   Last reconfirmed|                            |2021-09-14
     Ever confirmed|0                           |1

[Bug c++/102050] Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102050

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:2ab5c3d5457f0d480c6423ee7ac52ce1f98592c9

commit r12-3555-g2ab5c3d5457f0d480c6423ee7ac52ce1f98592c9
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Sep 15 13:54:53 2021 -0400

    c++: default ctor that's also a list ctor [PR102050]

    In grok_special_member_properties we need to set TYPE_HAS_COPY_CTOR,
    TYPE_HAS_DEFAULT_CONSTRUCTOR and TYPE_HAS_LIST_CTOR independently
    from each other because a constructor can be both a default and list
    constructor (as in the first testcase), or both a default and copy
    constructor (as in the second testcase).

            PR c++/102050

    gcc/cp/ChangeLog:

            * decl.c (grok_special_member_properties): Set
            TYPE_HAS_COPY_CTOR, TYPE_HAS_DEFAULT_CONSTRUCTOR
            and TYPE_HAS_LIST_CTOR independently from each other.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/initlist125.C: New test.
            * g++.dg/cpp0x/initlist126.C: New test.

[Bug c++/102050] Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102050

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

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

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 12.

[Bug c++/102050] Nonempty list-initialization rejects constructor with defaulted std::initializer_list

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102050

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppluzhnikov at google dot com

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 60437 has been marked as a duplicate of this bug. ***