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<title>Issue 2887: Revert the changes from P0156R0: variadic lock_guard</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#Resolved">Resolved</a> status.</em></p>
<h3 id="2887"><a href="lwg-defects.html#2887">2887</a>. Revert the changes from P0156R0: variadic <code>lock_guard</code></h3>
<p><b>Section:</b> 32.6.5.2 <a href="https://wg21.link/thread.lock.guard">[thread.lock.guard]</a> <b>Status:</b> <a href="lwg-active.html#Resolved">Resolved</a>
 <b>Submitter:</b> Finland, Great Britain <b>Opened:</b> 2017-02-03 <b>Last modified:</b> 2017-04-22</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#thread.lock.guard">issues</a> in [thread.lock.guard].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Resolved">Resolved</a> status.</p>
<p><b>Discussion:</b></p>
<b>Addresses FI 8, GB 61</b>

<p>The class template <code>lock_guard</code> was made variadic. This is abi-breaking, and confusing because one-argument 
<code>lock_guard</code>s have a typedef <code>mutex_type</code> but <code>lock_guard</code>s with more than one argument don't. There's 
no need to try to shoehorn this functionality into one type.</p>
<p>Proposed change: Revert the changes to <code>lock_guard</code>, and introduce a new variadic class template 
<code>vlock_guard</code> that doesn't have the <code>mutex_type</code> typedef at all.</p>

<p><i>[2017-02-02, Marshall notes]</i></p>

<p>This was the subject of intense discussion in Issaquah, and a joint LEG/LEWG session agreed on this approach.</p>

<p><i>[2017-03-12, post-Kona]</i></p>

<p>Resolved by P0156R2.</p>


<p id="res-2887"><b>Proposed resolution:</b></p>
<p>
</p>





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