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<title>Issue 963: Various threading bugs #13</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++11">C++11</a> status.</em></p>
<h3 id="963"><a href="lwg-defects.html#963">963</a>. Various threading bugs #13</h3>
<p><b>Section:</b> 32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> Pete Becker <b>Opened:</b> 2009-01-07 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#thread.thread.member">issues</a> in [thread.thread.member].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++11">C++11</a> status.</p>
<p><b>Discussion:</b></p>
<p>
32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a>:  <code>thread::detach</code> is required to
throw an exception if the thread is "not a detachable thread".
"Detachable" is never defined.
</p>

<p><i>[
Howard adds:
]</i></p>


<blockquote><p>
Due to a mistake on my part, 3 proposed resolutions appeared at approximately
the same time.  They are all three noted below in the discussion.
</p></blockquote>

<p><i>[
Summit, proposed resolution:
]</i></p>


<blockquote>
<p>
In 32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a> change:
</p>

<blockquote><pre>
void detach();
</pre>
<blockquote>
<p>...</p>
<p>-14- <i>Error conditions:</i></p>
<ul>
<li><code>no_such_process</code> --  <ins>if the thread is</ins> not <del>a</del> valid<del> thread</del>.</li>
<li><code>invalid_argument</code> -- <ins>if the thread is</ins> not <del>a detachable</del> <ins>joinable</ins><del> thread</del>.</li>
</ul>
</blockquote>

</blockquote>

</blockquote>

<p><i>[
Post Summit, Jonathan Wakely adds:
]</i></p>


<blockquote>
<p>
A <code>thread</code> is detachable if it is joinable. As we've defined joinable,
we can just use that.
</p>
<p>
This corresponds to the pthreads specification, where pthread_detach
fails if the thread is not joinable:
</p>
<blockquote><p>
EINVAL: The  implementation  has  detected  that  the value specified by
thread does not refer to a joinable thread.
</p></blockquote>
<p>
Jonathan recommends this proposed wording:
</p>
<blockquote>
<p>
In 32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a> change:
</p>

<blockquote><pre>
void detach();
</pre>
<blockquote>
<p>...</p>
<p>-14- <i>Error conditions:</i></p>
<ul>
<li>...</li>
<li><code>invalid_argument</code> -- not a <del>detachable</del> <ins>joinable</ins> thread.</li>
</ul>
</blockquote>

</blockquote>
</blockquote>
</blockquote>

<p><i>[
Post Summit, Anthony Williams adds:
]</i></p>


<blockquote>
<p>
This is covered by the precondition that <code>joinable()</code> be <code>true</code>.
</p>
<p>
Anthony recommends this proposed wording:
</p>

<blockquote>
<p>
In 32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a> change:
</p>

<blockquote><pre>
void detach();
</pre>
<blockquote>
<p>...</p>
<p>-14- <i>Error conditions:</i></p>
<ul>
<li>...</li>
<li><del><code>invalid_argument</code> -- not a detachable thread.</del></li>
</ul>
</blockquote>

</blockquote>

</blockquote>

</blockquote>

<p><i>[
2009-10 Santa Cruz:
]</i></p>


<blockquote><p>
Mark as Ready with proposed resolution from Summit.
</p></blockquote>



<p id="res-963"><b>Proposed resolution:</b></p>

<p>
In 32.4.3.6 <a href="https://wg21.link/thread.thread.member">[thread.thread.member]</a> change:
</p>

<blockquote><pre>
void detach();
</pre>
<blockquote>
<p>...</p>
<p>-14- <i>Error conditions:</i></p>
<ul>
<li><code>no_such_process</code> --  <ins>if the thread is</ins> not <del>a</del> valid<del> thread</del>.</li>
<li><code>invalid_argument</code> -- <ins>if the thread is</ins> not <del>a detachable</del> <ins>joinable</ins><del> thread</del>.</li>
</ul>
</blockquote>

</blockquote>






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