On Wed, Apr 22, 2020 at 5:28 PM JF Bastien via SG12 <sg12_at_[hidden]>
wrote:

> Maybe folks haven't moved from ub_at_[hidden] to sg12_at_[hidden] ?
>
> On Wed, Apr 22, 2020 at 8:34 AM Keane, Erich <erich.keane_at_[hidden]>
> wrote:
>
>> Hi all!
>>
>> Did this make it to the mailing list? I didn’t see any discussion on
>> this so I didn’t know if the group decided to just cover this in a telecon
>> that I didn’t hear about, or it just dropped 😊 I just wanted to make
>> sure it doesn’t get dropped.
>>
>>
>>
>> Thanks,
>> Erich
>>
>>
>>
>> *From:* Keane, Erich
>> *Sent:* Wednesday, April 15, 2020 8:56 AM
>> *To:* sg12_at_[hidden]
>> *Cc:* JF Bastien <cxx_at_[hidden]>
>> *Subject:* EWG Requests feedback/suggestions on Core Issue 1555
>>
>>
>>
>> Hi SG12-
>>
>> In the EWG telecon today, we discussed core issue 1555 (
>> http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_closed.html#1555). The
>> summary of the issue is that the standard makes function types of different
>> language linkage incompatible, thus calling a function from a pointer with
>> different language linkage is undefined behavior. One unnamed
>> implementation was referenced during the discussion where language linkage
>> effects calling convention.
>>
>>
>>
>> The major implementations (and none other than the 1 unnamed one listed)
>> simply don’t implement this restriction (that the types aren’t compatible)
>> because the calling convention is the same between the linkages.
>>
>>
>>
>> EWG was undecided as to whether we should remove this instance
>> restriction, or leave it as undefined behavior. None seemed to support
>> CWG1555’s proposed resolution of conditionally-supported behavior.
>>
> To clarify, the conditional support that was proposed maintained the
formal difference between the types and introduced conversions. There was
no discussion over whether it is implementation defined whether the types
are considered the same or not.


>
>>
>> (TL-DR people can start here😊 )
>>
>> The outcome of the discussion is that the impact and scope of this
>> Undefined Behavior should be evaluated by SG12, and if possible, provide a
>> set of recommendations for dealing with this core issue.
>>
>>
>>
>> -Erich
>>
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