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<title>Issue 2661: [filesys.ts] Surprising equivalent() behavior if neither file exists</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#NAD">NAD</a> status.</em></p>
<h3 id="2661"><a href="lwg-closed.html#2661">2661</a>. [filesys.ts] Surprising <code>equivalent()</code> behavior if neither file exists</h3>
<p><b>Section:</b> 6 [filesys.ts::fs.filesystem.synopsis] <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Beman Dawes <b>Opened:</b> 2014-04-12 <b>Last modified:</b> 2016-08-11</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#filesys.ts::fs.filesystem.synopsis">issues</a> in [filesys.ts::fs.filesystem.synopsis].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p><b>Addresses: filesys.ts</b></p>
<p>
  <code>
    bool equivalent(const path&amp; p1, const path&amp; p2);
  </code> has always thrown a exception if neither file exists,
   with rationale that if they don't exist, it isn't possible to tell
   if two paths are equivalent. Dave Abrahams has reported that this
   is counter-intuitive and hard to teach.
</p>
  <p>An alternative if neither path exists would be to return true
  if they are lexically equal (operator==), otherwise return false.</p>
  <p>This was not a national body comment, and Dave is the only one
  I can recall ever complaining about the current behavior. On the
  other hand, any complaint from Dave deserves serious consideration.</p>

  <p><i>[17 Jun 2014 Rapperswil LWG considers this NAD. Mixing lexical and existence based
  behavior is not desirable.]</i></p>




<p id="res-2661"><b>Proposed resolution:</b></p>
<p></p>





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