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<title>Issue 372: Inconsistent description of stdlib exceptions</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="372"><a href="lwg-closed.html#372">372</a>. Inconsistent description of stdlib exceptions</h3>
<p><b>Section:</b> 16.4.6.14 <a href="https://wg21.link/res.on.exception.handling">[res.on.exception.handling]</a>, 17.7.3 <a href="https://wg21.link/type.info">[type.info]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Randy Maddox <b>Opened:</b> 2002-07-22 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#res.on.exception.handling">active issues</a> in [res.on.exception.handling].</p>
<p><b>View all other</b> <a href="lwg-index.html#res.on.exception.handling">issues</a> in [res.on.exception.handling].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>

<p>Paragraph 3 under clause 16.4.6.14 <a href="https://wg21.link/res.on.exception.handling">[res.on.exception.handling]</a>, Restrictions on
Exception Handling, states that "Any other functions defined in the
C++ Standard Library that do not have an exception-specification may
throw implementation-defined exceptions unless otherwise specified."
This statement is followed by a reference to footnote 178 at the
bottom of that page which states, apparently in reference to the C++
Standard Library, that "Library implementations are encouraged (but
not required) to report errors by throwing exceptions from (or derived
from) the standard exceptions."</p>

<p>These statements appear to be in direct contradiction to clause
17.7.3 <a href="https://wg21.link/type.info">[type.info]</a>, which states "The class exception defines the
base class for the types of objects thrown as exceptions by the C++
Standard library components ...".</p>

<p>Is this inconsistent?</p>



<p id="res-372"><b>Proposed resolution:</b></p>


<p><b>Rationale:</b></p>
<p>Clause 17 is setting the overall library requirements, and it's
  clear and consistent.  This sentence from Clause 18 is descriptive,
  not setting a requirement on any other class.
</p>





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