P2186 Removing Garbage Collection Support

[wg21bot]

P2186R0 Removing Garbage Collection Support (JF Bastien, Alisdair Meredith)

[jfbastien]

EWG reviewed this in a telecon on July 30th and took the following non-binding poll:

Remove (not deprecate) garbage collection support in C++23.
SF F N A SA
3 9 4 0 1

[ben-craig]

P2186R0: Removing Garbage Collection Support

2020-12-14 Library Evolution Telecon Minutes

Chair: Ben Craig

Champion: JF Bastien

Minute Taker: Inbal Levi

Start: 2020-12-14 09:35 Pacific Standard

POLL: Remove (not deprecate) pointer safety in C++23, after moving names to zombie names.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
10	4	3	0	0

Attendance: 24

# of Authors: 1

Author Position: SF

Outcome: EWG may continue with this paper.

End: 09:45

SUMMARY:
The main discussion revolved around seeing if there were any implementations that implemented this, and discussing immediate removal vs. deprecation. LEWG was fine with immediate removal.

OUTCOME:
EWG may continue with this paper. Please add the removed names to [zombie.names]

[wg21bot]

P2186R1 Removing Garbage Collection Support (JF Bastien, Alisdair Meredith)

[jfbastien]

EWG February 2021 polls:

Poll: Forward P2186R1 "Removing Garbage Collection Support" to Core.

SF	F	N	A	SA
12	12	4	1	0

Poll outcome: ✅ consensus.

Salient comments:

• (Against) It does not seem to provide much harm, even if not used… And since the basic need seems genuine, I’d prefer to keep the mechanism until it is properly handled, than removing it and having to reintroduce something similar later.
  Clearly, no need to have unused utilities.
• To the best of my knowledge, this is unused and not implemented in implementations. The specification cost of keeping it is not zero.
• Given that 10 years after being standardized, this is not provided in any major implementation, it’s IMHO save to assume that "nobody" needs this/can use this due to the issues outlined in the paper.
• Implementations of garbage collection exist, yet do not rely on the "garbage collection support" in the Standard. Furthermore, the paper argues convincingly that the Standard’s "support" for garbage collection does not support common use cases, like placement new in local arrays.
• Keeping stuff in the standard that’s not supported and is lacking guidance for proper implementation makes little sense. Removing it might free space for a better, more useful specification that’s not restricted to cmpatibility.

[jensmaurer]

CWG 2021-03-22: Approved.

[JeffGarland]

Planned for LWG review 2021-04-16

[JeffGarland]

LWG adopted

https://wiki.edg.com/bin/view/Wg21telecons2021/P2186-20210416

Adopt P2816R2 Remove Garbage Collection Support for C++23
F N A
7 2 0

1 neutral vote was regarding discussion of object lifetime -- which was subsequently clarified to satisfaction after the vote.

[wg21bot]

P2186R2 Removing Garbage Collection Support (JF Bastien, Alisdair Meredith)

[wg21bot]

Adopted 2021-06.