[Bug c++/94682] New: coroutines: Promise param preview should get a reference to *this.

[Bug c++/94682] New: coroutines: Promise param preview should get a reference to *this.

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94682

            Bug ID: 94682
           Summary: coroutines: Promise param preview should get a
                    reference to *this.
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iains at gcc dot gnu.org
  Target Milestone: ---

Created attachment 48322
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48322&action=edit
fix being tested.

Reported independently by Michał Dominiak and Lewis Baker.

The static assert fails in the following code, because we should be passing a
reference to *this but we're passing this.

struct promise;

struct future
{
    using promise_type = promise;
};

struct promise
{
    template<typename Class>
    promise(Class &,int) { static_assert(!std::is_pointer<Class>::value, ""); }

    coro::suspend_never initial_suspend() { return {}; }
    coro::suspend_never final_suspend() { return {}; }

    future get_return_object() { return {}; }

    void return_value(int) {}
    void unhandled_exception() {}
};

struct bar
{
future foo(int param)
{
    co_return 0;
}
};

[Bug c++/94682] coroutines: Promise param preview should get a reference to *this.

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94682

Iain Sandoe <iains at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |iains at gcc dot gnu.org
     Ever confirmed|0                           |1
           Keywords|                            |wrong-code
   Target Milestone|---                         |10.0
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-04-21

[Bug c++/94682] coroutines: Promise param preview should get a reference to *this.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94682

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Iain D Sandoe <iains@gcc.gnu.org>:

https://gcc.gnu.org/g:38644f81babd04820daa9d622ea75eb68c066c86

commit r10-7868-g38644f81babd04820daa9d622ea75eb68c066c86
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Wed Apr 22 09:49:20 2020 +0100

    coroutines: Pass class reference to promise param preview [PR94682]

    As reported in the PR, per [dcl.fct.def.coroutine]/4 we should
    be passing a reference to the object to the promise parameter
    preview, and we are currently passing a pointer (this).  Amend to
    pass the reference.

    gcc/cp/ChangeLog:

    2020-04-22  Iain Sandoe  <iain@sandoe.co.uk>

            PR c++/94682
            * coroutines.cc (struct param_info): Add a field to note that
            the param is 'this'.
            (morph_fn_to_coro): Convert this to a reference before using it
            in the promise parameter preview.

    gcc/testsuite/ChangeLog:

    2020-04-22  Iain Sandoe  <iain@sandoe.co.uk>

            PR c++/94682
            * g++.dg/coroutines/pr94682-preview-this.C: New test.

[Bug c++/94682] coroutines: Promise param preview should get a reference to *this.

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94682

Iain Sandoe <iains at gcc dot gnu.org> changed:

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

--- Comment #2 from Iain Sandoe <iains at gcc dot gnu.org> ---
fixed.