P2609 Relaxing Ranges Just A Smidge

[wg21bot]

P2609R0 Relaxing Ranges Just A Smidge (John Eivind Helset)

[brycelelbach]

2022-06-28 Library Evolution Telecon

P2248R4: Enabling list-initialization for algorithms

2022-06-28 Library Evolution Telecon Minutes

P2609R0: Relaxing Ranges Just A Smidge

2022-06-28 Library Evolution Telecon P2609 Minutes

P2538R1: ADL-proof projected

2022-06-28 Library Evolution Telecon P2538 Minutes

Chair: Bryce Adelstein Lelbach

Minute Taker: Ben Craig

Champion: Giuseppe D'Angelo (P2248) & John Eivind Helset (P2609)

Start P2248: 2022-06-28 11:47 Eastern

POLL: Modify P2248R4 (Enabling list-initialization for algorithms) by making projected_value a metafunction defined in terms of invoke_result_t, and return the revised paper to Library for C++23 classified as B2 - Improvement, to be confirmed with a Library Evolution electronic poll.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
3	10	1	0	0

Attendance: 26

# of Authors: 1

Author Position: N

Outcome: Strong consensus in favor.

End: 11:55

POLL: Modify P2248R4 (Enabling list-initialization for algorithms) by making projected_value a metafunction defined in terms of invoke_result_t and extending the paper to ranges::fold and ranges::contains, and return the revised paper to Library for C++23 classified as B2 - Improvement, to be confirmed with a Library Evolution electronic poll.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
0	11	3	0	0

Attendance: 26

# of Authors: 1

Author Position: WF

Outcome: Consensus in favor.

N: Too much work for C++23.

POLL: Modify P2248R4 (Enabling list-initialization for algorithms) by making projected_value a metafunction defined in terms of invoke_result_t and extending the paper to ranges::fold and ranges::contains, and return the revised paper to Library for C++23 classified as B2 - Improvement, to be confirmed with a Library Evolution electronic poll.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
4	9	1	0	0

Attendance: 25

# of Authors: 1

Author Position: SF

Outcome: Strong consensus in favor.

We will go with the last poll.

End P2248: 12:03

Start P2609: 12:04

Does this paper have:

• Examples?
  • Yes.
• Field experience?
  • Implementation experience?
    • Yes, in ranges v3 and libstdc++.
• Wording?
  • Yes.
• Feature test macro?
  • No; we should modify the paper to bump the __cpp_lib_ranges feature
    test macro.

POLL: indirect_value_t should be exposition only.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
0	10	2	5	0

Attendance: 25

# of Authors: 1

Author Position: N

Outcome: No consensus; we'll leave it to the author's discretion.

POLL: Modify P2609R0 (Relaxing Ranges Just A Smidge) by bumping the __cpp_lib_ranges feature test macro, and send the revised paper to Library for C++26 classified as B2 - Improvement, to be confirmed with a Library Evolution electronic poll.

Strongly Favor	Weakly Favor	Neutral	Weakly Against	Strongly Against
6	11	0	0	0

Attendance: 24

# of Authors: 1

Author Position: SF

Outcome: Unanimous consensus in favor.

End: 12:37

If P2609 merges before P2248, P2248 should define projected_value in terms of indirect_value_t.

If P2248 merges before P2609, P2609 should update the definition of projected_value.

Summary

We discussed projected_value (from P2248) and indirect_value_t (from P2609), two metafunctions with a very similar definition.
We determined that we should try to ensure that they are defined in terms of each other, and that we wanted both to be concrete and not expositional.
We also decided that P2248 (Enabling list -initialization for algorithms) should be expanded to include two new algorithms that have been added since P2248 was forwarded, ranges::fold and ranges::contains.

Next Steps

• Produce and publish P2248R5 (Enabling list-initialization for algorithms), making projected_value a metafunction defined in terms of invoke_result_t and expanding the paper to include ranges::fold and ranges::contains
• Take an electronic poll to confirm sending P2248R5 (Enabling list-initialization for algorithms) to Library for C++23 classified as B2 - Improvement.
• Produce and publish P2609R1 (Relaxing Ranges Just A Smidge), bumping the __cpp_lib_ranges feature test macro.
• Take an electronic poll to confirm sending P2609R0 (Relaxing Ranges Just A Smidge) to Library for C++26 classified as B2 - Improvement.
• If P2609 merges before P2248, P2248 should define projected_value in terms of indirect_value_t.
• If P2248 merges before P2609, P2609 should update the definition of projected_value.