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<title>Issue 3871: Adjust note about terminate</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="3871"><a href="lwg-defects.html#3871">3871</a>. Adjust note about <code>terminate</code></h3>
<p><b>Section:</b> 16.4.2.5 <a href="https://wg21.link/compliance">[compliance]</a> <b>Status:</b> <a href="lwg-active.html#C++23">C++23</a>
 <b>Submitter:</b> CA <b>Opened:</b> 2023-02-01 <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#compliance">issues</a> in [compliance].</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>
This is the resolution for NB comment <b><a href="https://github.com/cplusplus/nbballot/issues/463">CA-076</a></b>
</p>
<p>
16.4.2.5 <a href="https://wg21.link/compliance">[compliance]</a> p4 has this note:
</p>
<blockquote>
[<i>Note 1</i>: Throwing a standard library provided exception is not
observably different from <code>terminate()</code> if the implementation
does not unwind the stack during exception handling
(14.4 <a href="https://wg21.link/except.handle">[except.handle]</a>)
and the user's program contains no catch blocks. &mdash; <i>end note</i>]
</blockquote>
<p>
Even under the conditions described by the note, a call to <code>terminate()</code>
is observably different from throwing an exception if the current
<code>terminate_handler</code> function observes what would have been
the currently handled exception in the case where the exception was thrown.
</p>
<p>
The set of conditions should be extended to include something along the lines of
"and the current <code>terminate_handler</code> function simply calls <code>abort()</code>".
</p>
<p><strong>Previous resolution [SUPERSEDED]:</strong></p>
<blockquote class="note">

<p>
This wording is relative to <a href="https://wg21.link/N4928" title=" Working Draft, Standard for Programming Language C++">N4928</a>.
</p>

<ol>
<li>
<p>
Modify 16.4.2.5 <a href="https://wg21.link/compliance">[compliance]</a>, "Freestanding implementations", as indicated:
</p>

<blockquote>
-4-
[<i>Note 1</i>: Throwing a standard library provided exception is not
observably different from <code>terminate()</code> if the implementation
does not unwind the stack during exception handling
(14.4 <a href="https://wg21.link/except.handle">[except.handle]</a>)
and the user's program contains no catch blocks
<ins>and the current <code>terminate_handler</code> function simply calls
<code>abort()</code></ins>.
&mdash; <i>end note</i>]
</blockquote>
</li>
</ol>

</blockquote>

<p><i>[Issaquah 2023-02-06; LWG]</i></p>

<p>If the note isn't true then remove it.<br/>
Poll: keep note and change as proposed? 3/1/10.<br/>
Poll: drop the note entirely? 10/0/5.<br/>
Drop the note and move to Immediate for C++20: 9/0/2.
</p>
<p><i>[2023-02-13 Approved at February 2023 meeting in Issaquah. Status changed: Immediate &rarr; WP.]</i></p>



<p id="res-3871"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N4928" title=" Working Draft, Standard for Programming Language C++">N4928</a>.
</p>

<ol>
<li>
<p>
Modify 16.4.2.5 <a href="https://wg21.link/compliance">[compliance]</a>, "Freestanding implementations", as indicated:
</p>

<blockquote>
<del>
-4-
[<i>Note 1</i>: Throwing a standard library provided exception is not
observably different from <code>terminate()</code> if the implementation
does not unwind the stack during exception handling
(14.4 <a href="https://wg21.link/except.handle">[except.handle]</a>)
and the user's program contains no catch blocks.
&mdash; <i>end note</i>]
</del>
</blockquote>
</li>
</ol>





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