New issue from Jakub: meta::data_member_spec allows negative bit-field widths

Author: jwakely

xml/issue4423.xml

@@ -0,0 +1,63 @@
+<?xml version='1.0' encoding='utf-8' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd">
+
+<issue num="4423" status="New">
+<title>`meta::data_member_spec` allows negative bit-field widths</title>
+<section><sref ref="[meta.reflection.define.aggregate]"/></section>
+<submitter>Jakub Jelinek</submitter>
+<date>20 Oct 2025</date>
+<priority>99</priority>
+
+<discussion>
+<p>
+The `meta::data_member_spec` function doesn't restrict `options.bit_width`
+to be non-negative.
+</p>
+</discussion>
+
+<resolution>
+<p>
+This wording is relative to <paper num="N5014"/>.
+</p>
+
+<ol>
+
+<li><p>Modify <sref ref="[meta.reflection.define.aggregate]"/> as indicated:</p>
+
+<blockquote>
+<ul>
+<li>(5.3) &mdash;
+if `options.name` does not contain a value, then `options.bit_width`
+contains a value;
+</li>
+<li>(5.4) &mdash;
+if `options.bit_width` contains a value <i>V</i>, then
+<ul>
+<li>(5.4.1) &mdash;
+`is_integral_type(type) || is_enum_type(type)` is `true`,
+</li>
+<li>(5.4.2) &mdash;
+`options.alignment` does not contain a value,
+</li>
+<li>(5.4.3) &mdash;
+`options.no_unique_address` is `false`, <del>and</del>
+</li>
+<li><ins>(5.4.?) &mdash;
+<i>V</i> is not negative, and</ins>
+</li>
+<li>(5.4.4) &mdash;
+if <i>V</i> equals `0`, then `options.name` does not contain a value; and
+</li>
+</ul>
+</li>
+<li>(5.5) &mdash;
+if `options.alignment` contains a value, it is an alignment value
+(<sref ref="[basic.align]"/>) not less than `alignment_of(type)`.
+</li>
+</ul>
+</blockquote>
+</li>
+</ol>
+</resolution>
+
+</issue>