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<title>Issue 3396: Clarify point of reference for source_location::current() (DE 169)</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++20">C++20</a> status.</em></p>
<h3 id="3396"><a href="lwg-defects.html#3396">3396</a>. Clarify point of reference for <code>source_location::current()</code> (DE 169)</h3>
<p><b>Section:</b> 17.8.2.2 <a href="https://wg21.link/support.srcloc.cons">[support.srcloc.cons]</a> <b>Status:</b> <a href="lwg-active.html#C++20">C++20</a>
 <b>Submitter:</b> Jens Maurer <b>Opened:</b> 2020-02-13 <b>Last modified:</b> 2021-02-25</p>
<p><b>Priority: </b>2
</p>
<p><b>View all other</b> <a href="lwg-index.html#support.srcloc.cons">issues</a> in [support.srcloc.cons].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++20">C++20</a> status.</p>
<p><b>Discussion:</b></p>
<p><b>Addresses <a href="https://github.com/cplusplus/nbballot/issues/167">DE 169</a></b></p>
<p>
The expectation of the note that a default argument expression
involving current() causes a source_location to be constructed
that refers to the site of a function call where that default
argument is needed has no basis in normative text.
In particular, 9.2.3.6 paragraph 5 seems to imply that the
name "current" and its semantics are bound where it appears
lexically in the function declaration.
<p/>
Proposed change:
<p/>
Add normative text to express the desired semantics.
</p>

<p><i>[2020-02 Moved to Immediate on Thursday afternoon in Prague.]</i></p>



<p id="res-3396"><b>Proposed resolution:</b></p>
<p>This wording is relative to <a href="https://wg21.link/n4849">N4849</a>.</p>

<ol>
<li><p>Modify 17.8.2.2 <a href="https://wg21.link/support.srcloc.cons">[support.srcloc.cons]</a> as indicated:</p>

<blockquote>
<pre>
static consteval source_location current() noexcept;
</pre>
<blockquote>
<p>
-1- [&hellip;]
<p/>
-2- <i>Remarks:</i> <del>When a default member initializer is used to initialize a non-static data member, any calls to
<code>current</code></del><ins>Any call to <code>current</code> that appears as a default member initializer (11.4 <a href="https://wg21.link/class.mem">[class.mem]</a>), 
or as a subexpression thereof,</ins> should correspond to the location of the constructor <ins>definition</ins> or 
aggregate initialization that <del>initializes the member</del><ins>uses the default member initializer</ins>. 
<ins>Any call to <code>current</code> that appears as a default argument (9.3.4.7 <a href="https://wg21.link/dcl.fct.default">[dcl.fct.default]</a>), or as a subexpression thereof, 
should correspond to the location of the invocation of the function that uses the default argument (7.6.1.3 <a href="https://wg21.link/expr.call">[expr.call]</a>).</ins>
<p/>
<del>-3- [<i>Note:</i> When used as a default argument (9.3.4.7 <a href="https://wg21.link/dcl.fct.default">[dcl.fct.default]</a>), the value of the 
<code>source_location</code> will be the location of the call to <code>current</code> at the call site. &mdash; <i>end note</i>]</del>
</p>
</blockquote>
</blockquote>
</li>

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