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<title>Issue 1094: Replace "unspecified-bool-type" by "explicit operator bool() const" in I/O library</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="1094"><a href="lwg-defects.html#1094">1094</a>. Replace "<em>unspecified-bool-type</em>" by "<code>explicit operator bool() const</code>" in I/O library</h3>
<p><b>Section:</b> 31.5.4.4 <a href="https://wg21.link/iostate.flags">[iostate.flags]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> P.J. Plauger <b>Opened:</b> 2009-03-24 <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#iostate.flags">issues</a> in [iostate.flags].</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><b>Addresses JP 65 and JP 66 [CD1]</b></p>

<p>
Switch from "unspecified-bool-type" to "explicit operator bool() const". 
</p>

<p>
Replace <code>operator unspecified-bool-type() const;</code>" with <code>explicit operator bool() const;</code>
</p>

<p><i>[
Batavia (2009-05):
]</i></p>

<blockquote><p>
We agree with the proposed resolution.
Move to Review.
</p></blockquote>

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


<blockquote><p>
Moved to Ready.
</p></blockquote>



<p id="res-1094"><b>Proposed resolution:</b></p>
<p>
Change the synopis in 31.5.4 <a href="https://wg21.link/ios">[ios]</a>:
</p>

<blockquote><pre>
<ins>explicit</ins> operator <del><i>unspecified-bool-type</i></del> <ins>bool</ins>() const;
</pre></blockquote>

<p>
Change 31.5.4.4 <a href="https://wg21.link/iostate.flags">[iostate.flags]</a>:
</p>

<blockquote><pre>
<ins>explicit</ins> operator <del><i>unspecified-bool-type</i></del> <ins>bool</ins>() const;
</pre>

<blockquote>
<p>
-1- <i>Returns:</i> <ins><code>!fail()</code></ins> <del>If <code>fail()</code> then a value that will evaluate
false in a boolean context; otherwise a value that will evaluate true in
a boolean context. The value type returned shall not be convertible to
int.</del>
</p>
<p>
<del>[<i>Note:</i> This conversion can be used in contexts where a bool is expected
(e.g., an <code>if</code> condition); however, implicit conversions (e.g.,
to <code>int</code>) that can occur with <code>bool</code> are not allowed,
eliminating some sources of user error. One possible implementation
choice for this type is pointer-to-member. <i>-- end note</i>]</del>
</p>
</blockquote>
</blockquote>







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