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<title>Issue 3707: chunk_view::outer-iterator::value_type::size should return unsigned type</title>
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<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#C++23">C++23</a> status.</em></p>
<h3 id="3707"><a href="lwg-defects.html#3707">3707</a>. <code>chunk_view::<i>outer-iterator</i>::value_type::size</code> should return unsigned type</h3>
<p><b>Section:</b> 25.7.29.4 <a href="https://wg21.link/range.chunk.outer.value">[range.chunk.outer.value]</a> <b>Status:</b> <a href="lwg-active.html#C++23">C++23</a>
 <b>Submitter:</b> Hewill Kang <b>Opened:</b> 2022-06-01 <b>Last modified:</b> 2023-11-22</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#range.chunk.outer.value">issues</a> in [range.chunk.outer.value].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++23">C++23</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Currently, the <code>size</code> function of <code>chunk_view::<i>outer-iterator</i>::value_type</code> returns 
the result of <code>ranges::min</code>, since the operands are of type <code>range_difference_t&lt;V&gt;</code>, 
this will return a signed type, which is inconsistent with the return type of <code>size</code> of the 
<code>forward</code>-version of <code>chunk_view::<i>iterator</i>::value_type</code> (25.7.29.7 <a href="https://wg21.link/range.chunk.fwd.iter">[range.chunk.fwd.iter]</a>), 
which always returns an unsigned type.
</p>
<p>
I think it's more reasonable to return an unsigned type, since this is intentional behavior and 
doesn't fall back to using the default <code>view_interface::size</code>.
And if LWG <a href="lwg-defects.html#3646" title="std::ranges::view_interface::size returns a signed type (Status: C++23)">3646</a><sup><a href="https://cplusplus.github.io/LWG/issue3646" title="Latest snapshot">(i)</a></sup> is eventually adopted, there's no reason why it shouldn't be made 
unsigned.
</p>

<p><i>[2022-06-21; Reflector poll]</i></p>

<p>
Set status to Tentatively Ready after five votes in favour during reflector poll.
</p>

<p><i>[2022-07-15; LWG telecon: move to Ready]</i></p>


<p><i>[2022-07-25 Approved at July 2022 virtual plenary. Status changed: Ready &rarr; WP.]</i></p>



<p id="res-3707"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N4910" title=" Working Draft, Standard for Programming Language C++">N4910</a>.
</p>

<ol>
<li><p>Modify 25.7.29.4 <a href="https://wg21.link/range.chunk.outer.value">[range.chunk.outer.value]</a> as indicated:</p>

<blockquote>
<pre>
constexpr auto size() const
  requires sized_sentinel_for&lt;sentinel_t&lt;V&gt;, iterator_t&lt;V&gt;&gt;;
</pre>
<blockquote>
<p>
-4- <i>Effects:</i> Equivalent to:
</p>
<blockquote><pre>
return <ins><i>to-unsigned-like</i>(</ins>ranges::min(<i>parent_</i>-&gt;<i>remainder_</i>, ranges::end(<i>parent_</i>-&gt;<i>base_</i>) - *<i>parent_</i>-&gt;<i>current_</i>)<ins>)</ins>;
</pre></blockquote>
</blockquote>
</blockquote>
</li>

</ol>





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