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P2255 A type trait to detect reference binding to temporary #949

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wg21bot opened this issue Nov 23, 2020 · 7 comments
Open

P2255 A type trait to detect reference binding to temporary #949

wg21bot opened this issue Nov 23, 2020 · 7 comments

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@wg21bot
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@wg21bot wg21bot commented Nov 23, 2020

P2255R0 A type trait to detect reference binding to temporary (Tim Song)

@wg21bot
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@wg21bot wg21bot commented Apr 25, 2021

P2255R1 A type trait to detect reference binding to temporary (Tim Song)

@jfbastien
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@jfbastien jfbastien commented May 12, 2021

EWG saw the paper in today's telecon.

Send P2255r1 to LEWG, with a recommendation to send it to Electronic Polling with the currently specified semantics. Only do so if LEWG agrees that the type traits as specified are useful and usable for pair, tuple, and function.

SF F N A SA
3 9 0 0 0

@jfbastien jfbastien removed the EWG label May 12, 2021
@inbal2l
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@inbal2l inbal2l commented May 20, 2021

A short summary of the comments from LEWG's Mailing list:

  • std::tuple<const std::string&> x("hello"); is ill-formed, but the usage f(tuple<const string&>("hello")) seems desirable
    Author: I lean toward defining the ctor as deleted, so that the example is still rejected. tuple<const string&>("hello"s) (or the equivalent std::string("hello")) remains available.
  • Worried about false positives the trait may produce.
    Author: It produces an inevitably-dangling reference with tuple as specified today. Whether we go on to produce a likely-dangling reference or just reject the code outright seems like a somewhat separate decision to me; either way, it doesn't affect any existing valid C++20 code.

R1 is ready for LEWG Telecon.

@wg21bot
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@wg21bot wg21bot commented Oct 26, 2021

P2255R2 A type trait to detect reference binding to temporary (Tim Song)

@inbal2l
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@inbal2l inbal2l commented Oct 27, 2021

2021-10-26 Library Evolution Telecon

P2255R2: A type trait to detect reference binding to temporary

2021-10-26 Library Evolution Telecon Minutes

Chair: Inbal Levi

Champion: Tim Song

Minute Taker: Ben Craig

Polls

POLL: Forward P2255R2: A type trait to detect reference binding to temporary to LWG for C++23 (to be confirmed with electronic poll) with priority 2.

Strongly Favor Weakly Favor Neutral Weakly Against Strongly Against
1 3 4 1 0

Attendance: 15

# of Authors: 1

Author Position: SF

Outcome: No consensus

Outcome

The author was requested to start a thread on the mailing list on this topic, and if supported, go back to LEWG for polling.

@brycelelbach
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@brycelelbach brycelelbach commented Oct 31, 2021

@cor3ntin
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@cor3ntin cor3ntin commented Dec 6, 2021

November electronic polling

Send [P2255R2] (A Type Trait To Detect Reference Binding To Temporary) to Library Working Group for C++23, classified as an addition ([P0592R4] bucket 3 item).

SF F N A SA
14 12 1 0 0

Strong consensus in favor

@jensmaurer jensmaurer removed this from the 2021-telecon milestone Jan 1, 2022
@jensmaurer jensmaurer added this to the 2022-telecon milestone Jan 1, 2022
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