New issue from Matthias Kretz: "std::simd::bit_ceil should not be noexcept"

Author: Dani-Hub

xml/issue4375.xml

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+<?xml version='1.0' encoding='utf-8' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd">
+
+<issue num="4375" status="New">
+<title>`std::simd::bit_ceil` should not be `noexcept`</title>
+<section>
+<sref ref="[simd.bit]"/>
+</section>
+<submitter>Matthias Kretz</submitter>
+<date>29 Aug 2025</date>
+<priority>99</priority>
+
+<discussion>
+<p>
+`std::simd::bit_ceil` is declared 'noexcept' in <sref ref="[simd.syn]"/> and 
+<sref ref="[simd.bit]"/>. But
+</p>
+<ol>
+<li><p>`std::bit_ceil` is not 'noexcept' (<sref ref="[bit.syn]"/> and <sref ref="[bit.pow.two]"/>) and</p></li>
+<li><p>`std::simd::bit_ceil` has a precondition.</p></li>
+</ol>
+</discussion>
+
+<resolution>
+<p>
+This wording is relative to <paper num="N5014"/>.
+</p>
+
+<ol>
+
+<li><p>Modify <sref ref="[simd.syn]"/>, header <tt>&lt;simd&gt;</tt> synopsis, as indicated:</p>
+
+<blockquote>
+<pre>
+namespace std {
+  [&hellip;]
+  // <i><sref ref="[simd.bit]"/>, bit manipulation</i>
+  template&lt;<i>simd-vec-type</i> V&gt; constexpr V byteswap(const V&amp; v) noexcept;
+  template&lt;<i>simd-vec-type</i> V&gt; constexpr V bit_ceil(const V&amp; v) <del>noexcept</del>;
+  template&lt;<i>simd-vec-type</i> V&gt; constexpr V bit_floor(const V&amp; v) noexcept;  
+  [&hellip;]
+}
+</pre>
+</blockquote>
+
+</li>
+
+<li><p>Modify <sref ref="[simd.bit]"/> as indicated:</p>
+
+<blockquote>
+<pre>
+template&lt;<i>simd-vec-type</i> V&gt; constexpr V bit_ceil(const V&amp; v) <del>noexcept</del>;
+</pre>
+<blockquote>
+<p>
+-3- <i>Constraints</i>: The type `V::value_type` is an unsigned integer type (<sref ref="[basic.fundamental]"/>).
+<p/>
+-4- <i>Preconditions</i>: [&hellip;]
+<p/>
+[&hellip;]
+</p>
+</blockquote>
+</blockquote>
+
+</li>
+
+</ol></resolution>
+
+</issue>