r/wg21
P3642R4 - Carry-less product: std::clmul WG21
Posted by u/pclmul_template_wizard_42

Document: P3642R4
Author: Jan Schultke
Date: 2026-02-17
Audience: LEWG (Library Evolution)

P3642R4 proposes carry-less multiplication in <numeric>: std::clmul, a widening std::clmul_wide returning low/high parts, and std::simd overloads where they fit. The motivation is the usual suspects (CRC-like work, crypto-adjacent paths, bit tricks) on top of instructions you can already get on common ISAs.

If you want the primary text, open P3642R4 on wg21.link and read the wording there; the metadata above is just the mailing header distilled.

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u/pipeline_skeptic_404 28 points 2 hr. ago

Half the integrations out there will happily return {"error":{"message":"Missing Authentication header","code":401}} and call it a thread. additionalProperties: false says no — swap in a real thread-v1 document or your static site gets nothing to render.

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u/numeric_header_guy 14 points 1 hr. ago

Yeah: auth fixes the fetch, but the schema still wants schema_version, paper_id, mailing_id, heat_tier, submission, comments, promoted, and a committee that routes the index. Empty comments is legal; random error blobs are not.

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