P3774 R1 Rename std::nontype, and make it broadly useful

[wg21bot]

P3774R0 Rename std::nontype, and make it broadly useful (Jan Schultke, Bronek Kozicki, Tomasz Kamiński)

[wg21bot]

P3774R1 Rename std::nontype, and make it broadly useful (Jan Schultke, Bronek Kozicki, Tomasz Kamiński)

[inbal2l]

2025-08-12 Library Evolution Telecon

P3774R0: Rename std::nontype, and make it broadly useful
(Seen with: "P3794R0: An idea or two on renaming the nontype tag")

2025-08-12 Library Evolution Telecon Minutes

Champion: Jan Schultke / Zhihao Yuan
Chair: Fabio Fracassi
Minute Taker: Mark Hoemmen

Summary

POLL: We want to explore replacing nontype with constant_wrapper instead of renaming.

SF	F	N	A	SA
2	1	3	7	4

Attendance: 20
Author's Position: 3xSA
Outcome: Consensus against

POLL: We want to rename std::nontype.

SF	F	N	A	SA
6	6	3	0	1

Attendance: 20
Author's Position: 3xSF
Outcome: Consensus in favor

POLL: Approval poll (you can vote multiple times):

Name	Votes
std::fn / std::fn_t	6
std::fw / std::function_wrapper	10
std::fw / std::function_wrapper_t	3
std::const_fn / std::const_fn_t	5
std::witness / std::witness_t	1
std::constant_arg / std::constant_arg_t	7

Attendance: 20
# of Authors: 3
Outcome: std::fw / std::function_wrapper, std::constant_arg / std::constant_arg_t had most support

POLL: We prefer std::constant_arg/std::constant_arg_t over std::fw/std::function_wrapper (simple majority)

Strongly for const	Weakly for const	N	Weakly for fw	Strongly fw
2	4	3	2	5

Attendance: 20
Author's Position: N, SFw, SFw
Outcome: Most votes for std::fw (very close)

POLL: We want to rename std::nontype/std::nontype_t to std::fw / std::function_wrapper.

SF	F	N	A	SA
5	3	2	1	3

Attendance: 20
Author's Position: 3xSF
Outcome: No consensus for change

POLL: We want to rename std::nontype/std::nontype_t to std::constant_arg / std::constant_arg_t.

SF	F	N	A	SA
7	6	2	1	1

Attendance: 20
Author's Position: 3xSF
Outcome: consensus in favor

POLL: In P3774R0 change the name to std::constant_arg / std::constant_arg_t, without moving the facility to and forward the resulting revision to LWG for C++26 (to be confirmed by electronic poll).

SF	F	N	A	SA
8	4	1	0	1

Attendance: 19
Author's Position: 3xSF
Outcome: consensus in favor

Paper forwarding checklist

• Why should this utility go into the standard library? - fix for C++26
• Discussion of prior art? - yes
• Examples? - yes
• Field experience
  • Implementation experience? - yes
  • Usage experience? - no
  • Deployment experience? - no
• Performance considerations? - yes
• Support in "std::format" and "hash" (if required)? - N/A
• Feature test macro? - N/A
• Freestanding? - N/A
• constexpr? - N/A
• Changes Library Evolution previously requested? - yes
• Wording? - Yes

Next Steps

Polls indicated consensus for renaming ::non_type, with highest votes being for: std::fw / std::function_wrapper, std::constant_arg / std::constant_arg_t. There was consensus for “std::constant_arg / std::constant_arg_t”; the authors dropped the additional suggestion for moving to a different header. Paper was forwarded with the renaming change only (to be confirmed by an electronic poll).

[inbal2l]

P3774R1 was added to October 2025 LEWG EP paper (P3872R0)

[inbal2l]

Associated NB comments:

• https://github.com/cplusplus/nbballot/issues/779
• https://github.com/cplusplus/nbballot/issues/788

[JeffGarland]

LWG will see this in Kona

[bstamour]

LWG saw this Thursday morning in Kona.

Poll: put P3774R1 in C++26, addressing various NB comments
F N A
5 1 1