[Bug libstdc++/94199] New: std::experimental::net::v1::make_service function template not instantiatable

[Bug libstdc++/94199] New: std::experimental::net::v1::make_service function template not instantiatable

[erich.keane at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

            Bug ID: 94199
           Summary: std::experimental::net::v1::make_service function
                    template not instantiatable
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: erich.keane at intel dot com
  Target Milestone: ---

Discovered in Clang, since Clang diagnoses the issue without an instantiation,
here is a GCC repro: https://godbolt.org/z/7guiic

The function template tries to throw service_already_exists, which isn't
default constructible:


/opt/compiler-explorer/gcc-trunk-20200316/include/c++/10.0.1/experimental/executor:581:8:
error: use of deleted function
'std::experimental::net::v1::service_already_exists::service_already_exists()'

  581 |  throw service_already_exists();

Clang diagnoses just attempting to #include the file:
https://godbolt.org/z/yH9kNp

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |ASSIGNED
            Version|unknown                     |9.3.0
           Assignee|unassigned at gcc dot gnu.org      |redi at gcc dot gnu.org
   Target Milestone|---                         |9.4
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-03-16

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

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

https://gcc.gnu.org/g:c62f5e6e1f457462b1cea74792833821bbea64bb

commit r10-7200-gc62f5e6e1f457462b1cea74792833821bbea64bb
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Mar 16 22:53:42 2020 +0000

    libstdc++: Add default constructor to net::service_already_exists (PR
94199)

    The service_already_exists exception type specified in the TS doesn't
    have any constructors defined. Since its base class isn't default
    constructible, that means has no usable constructors. This may be a
    defect in the TS.

    This patch fixes it by adding a default constructor, but making it
    private. The make_service function is declared as a friend to be able to
    call that private constructor.

            PR libstdc++/94199
            * include/experimental/executor (service_already_exists): Add
default
            constructor. Declare make_service to be a friend.
            * testsuite/experimental/net/execution_context/make_service.cc: New
            test.

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:31b204ace293b81fc51f76bf9faf459ab1cd7c50

commit r9-8381-g31b204ace293b81fc51f76bf9faf459ab1cd7c50
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Mar 16 22:55:48 2020 +0000

    libstdc++: Add default constructor to net::service_already_exists (PR
94199)

    The service_already_exists exception type specified in the TS doesn't
    have any constructors defined. Since its base class isn't default
    constructible, that means has no usable constructors. This may be a
    defect in the TS.

    This patch fixes it by adding a default constructor, but making it
    private. The make_service function is declared as a friend to be able to
    call that private constructor.

    Backport from mainline
    2020-03-16  Jonathan Wakely  <jwakely@redhat.com>

            PR libstdc++/94199
            * include/experimental/executor (service_already_exists): Add
default
            constructor. Declare make_service to be a friend.
            * testsuite/experimental/net/execution_context/make_service.cc: New
            test.

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

Jonathan Wakely <redi at gcc dot gnu.org> changed:

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

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed. Thanks for the report.

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[erich.keane at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

--- Comment #4 from Erich Keane <erich.keane at intel dot com> ---
Thanks Jonathan!

[Bug libstdc++/94199] std::experimental::net::v1::make_service function template not instantiatable

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94199

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I've reported a new library issue (LWG 3414) suggesting we add a public default
constructor.