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Subject: Re: [isocpp-lib] Is it intentional that P0357R3 "Supporting Incomplete Types In reference_wrapper" has no feature test macro in N4842?
From: Casey Carter (cartec69_at_[hidden])
Date: 2020-01-08 20:08:46


On Wed, Jan 8, 2020 at 6:04 PM Billy O'Neal (VC LIBS) via Lib <
lib_at_[hidden]> wrote:

> No idea, I’m not saying I want to **use** the macro; I’m just adding a
> test for the feature (as part of processing
> https://github.com/microsoft/STL/pull/393 ) and making sure I didn’t miss
> adding the correct macro.
>

There is no macro, so you didn't miss it ;)

>
>
> Billy3
>
>
>
> *From:* Barry Revzin <barry.revzin_at_[hidden]>
> *Sent:* Wednesday, January 8, 2020 5:48 PM
> *To:* Library Working Group <lib_at_[hidden]>
> *Cc:* Billy O'Neal (VC LIBS) <bion_at_[hidden]>; sg10_at_[hidden]
> *Subject:* Re: [isocpp-lib] Is it intentional that P0357R3 "Supporting
> Incomplete Types In reference_wrapper" has no feature test macro in N4842?
>
>
>
> On Thu, Jan 9, 2020, 9:15 AM Billy O'Neal (VC LIBS) via Lib <
> lib_at_[hidden]> wrote:
>
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1902r1.html
> <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.open-std.org%2Fjtc1%2Fsc22%2Fwg21%2Fdocs%2Fpapers%2F2019%2Fp1902r1.html&data=02%7C01%7Cbion%40microsoft.com%7C28169c61cdbe4a3e983f08d794a5fcd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637141312938668697&sdata=tqedXcGVyVjqcsRTLvQHkbKcNXtfzOlLQ2pGLj3Lbug%3D&reserved=0>
> says “no macro necessary”. Should I take such attributions in that paper as
> “SG6 looked at it and is OK with no macro”?
>
>
>
> Billy3
>
>
>
> +SG10 (is it too late to rename our document to SD10 for consistency?)
>
>
>
> The paper just adds support for incomplete types to reference_wrapper.
> What code would you write based on the presence of that feature?
>

A third-party library might choose to whether implement reference_wrapper
with support for incomplete types or use std::reference_wrapper - to better
interoperate with other code - on the basis of such a feature-test macro.



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