New issue from Jonathan: std::text_encoding::aliases_view should have constexpr iterators

Author: jwakely

xml/issue4038.xml

@@ -0,0 +1,60 @@
+<?xml version='1.0' encoding='utf-8' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd">
+
+<issue num="4038" status="New">
+<title><code>std::text_encoding::aliases_view</code> should have constexpr iterators</title>
+<section><sref ref="[text.encoding.aliases]"/></section>
+<submitter>Jonathan Wakely</submitter>
+<date>16 Jan 2024</date>
+<priority>99</priority>
+
+<discussion>
+<p>
+<code>aliases_view::begin()</code> and <code>aliases_view::end()</code>
+are constexpr functions, but there is no requirement that you can use
+the returned iterator and sentinel in constant expressions.
+</p>
+</discussion>
+
+<resolution>
+<p>
+This wording is relative to <paper num="N4971"/>.
+</p>
+
+<ol>
+<li><p>Modify <sref ref="[text.encoding.aliases]"/> as indicated:</p>
+
+<blockquote>
+<blockquote>
+<pre>
+struct text_encoding::aliases_view : ranges::view_interface&lt;text_encoding::aliases_view&gt; {
+  constexpr <i>implementation-defined</i> begin() const;
+  constexpr <i>implementation-defined</i> end() const;
+};
+</pre>
+</blockquote>
+<p>
+-1-
+<code>text_encoding::aliases_view</code> models <code>copyable</code>,
+<code>ranges::view</code>, <code>ranges::random_access_range</code>,
+and <code>ranges::borrowed_range</code>.
+</p>
+<p>
+-2-
+Both <code>ranges::range_value_t&lt;text_encoding::aliases_view&gt;</code>
+and <code>ranges::range_reference_t&lt;text_encoding::aliases_view&gt;</code>
+denote <code>const char*</code>.
+</p>
+<p>
+<ins>
+-?-
+<code>ranges::iterator_t&lt;text_encoding::aliases_view&gt;</code>
+is a constexpr iterator (<sref ref="[iterator.requirements.general]"/>).
+</ins>
+</p>
+</blockquote>
+</li>
+</ol>
+</resolution>
+
+</issue>