Title
Disallow user specialization of <simd> templates
Status
ready
Section
[simd.general]
Submitter
Tim Song

Created on 2026-03-05.00:00:00 last changed yesterday

Messages

Date: 2026-03-06.17:21:58

Proposed resolution:

This wording is relative to N5032.

  1. Add the following paragraph to the end of [simd.general]:

    -?- If a program declares an explicit or partial specialization of any of the templates specified in subclause [simd], the program is ill-formed, no diagnostic required.

  2. Strike [simd.traits] p3 as redundant:

    -3- The behavior of a program that adds specializations for `alignment` is undefined.

Date: 2026-03-06.00:00:00

[ 2026-03-06 LWG telecon; move to Ready ]

Date: 2026-03-05.00:00:00
Addresses US 176-280.

It does not appear that any of the class templates in <simd> can be profitably specialized by the user – or that the non-member functions can be used with such user specializations.

History
Date User Action Args
2026-03-06 17:21:58adminsetmessages: + msg16012
2026-03-06 17:21:58adminsetstatus: new -> ready
2026-03-06 10:40:28adminsetmessages: + msg16005
2026-03-05 00:00:00admincreate