P3480R1 std::simd is a range (Matthias Kretz)

SG9 discussed this paper in Wroclaw. We forwarded it to LEWG.

We want std::basic_simd to be a range.

Attendance: 8
Author: SF

Unanimous consent.

We want std::basic_simd to be a common range.

Attendance: 8
Author: A

No consensus for change.

We want std::basic_simd::operator[] and std::basic_simd::begin/end in C++26 without mutation support, knowing that we might not be able to do it later due to ABI issues (e.g. decltype(auto) f(std::simd<float> x) { return x[0]; } could change return type).

Attendance: 8
Author: SF

Unanimous consent.

We want std::basic_simd::iterator and std::basic_simd::const_iterator to be different types to make the transition to mutable iteration easier. This also means adding a non-const begin() overload that returns a different type than the const begin() overload but currently has the same semantics.

Attendance: 8
Author: N

Consensus in favor.

Use std::default_sentinel_t instead of simd-iterator-sentinel.

No objection to unanimous consent.

Forward P3480R1 with the changes above to LEWG for inclusion in C++26.

Attendance: 8
Author: SF

Unanimous consent.

P3480R2 std::simd is a range (Matthias Kretz)

P3480R3 std::simd is a range (Matthias Kretz)

P3480R4 std::simd is a range (Matthias Kretz)

2025-04-08 Library Evolution Telecon

P3480R4: std::simd is a range

2025-04-08 Library Evolution Hagenberg Minutes

Champion: Matthias Kretz
Chair: Fabio Fracassi
Minute Taker: Khalil Estell

Summary

ACTION: Apply the fix: apply what’s in #if LEWG_WANTS_CONVERSION

POLL: Modify “P3480R4: std::simd is a range” with the above action items and forward to LWG for C++29 (with a recommendation to make this a DR for 26)

Attendance: 20
Author's Position: SF
Outcome: Strong consensus in favour

POLL: Modify “P3480R4: std::simd is a range” with the above action items and forward to LWG with a recommendation to apply for C++26 (if possible).

Attendance: 20
Author's Position: SF
Outcome: Strong consensus in favour

Next Steps

Apply the action item and forward the fixed revision to LWG for C++29 (with a recommendation to apply as DR). If possible, LEWG recommended to apply this in 26 timeframe.