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    CWG Issue 2251</TITLE>
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<P><EM>This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21
  Core Issues List revision 118b.
  See http://www.open-std.org/jtc1/sc22/wg21/ for the official
  list.</EM></P>
<P>2025-09-28</P>
<HR>
<A NAME="2251"></A><H4>2251.
  
Unreachable enumeration list-initialization
</H4>
<B>Section: </B>9.5.5&#160; [<A href="https://wg21.link/dcl.init.list">dcl.init.list</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++17
 &#160;&#160;&#160;

 <B>Submitter: </B>Richard Smith
 &#160;&#160;&#160;

 <B>Date: </B>2016-03-22<BR>


<P>[Adopted at the February/March, 2017 meeting.]</P>



<P>P0138R2 adds a new bullet for enum initialization after bullet 8 of
9.5.5 [<A href="https://wg21.link/dcl.init.list#3">dcl.init.list</A>] paragraph 3. However, paragraph 7 already
dealt with all the cases where the initializer list contains a single
element and the target type is a non-reference type, so the new
paragraph 9 rule is unreachable.</P>

<P><B>Proposed resolution (December, 2016):</B></P>

<P>Reorder the bullets in 9.5.5 [<A href="https://wg21.link/dcl.init.list#3">dcl.init.list</A>] paragraph 3 as
follows:</P>

<BLOCKQUOTE>

<P>List-initialization of an object or reference of type <TT>T</TT> is
defined as follows:</P>

<UL>
<LI><P>...</P></LI>

<LI><P>Otherwise, if <TT>T</TT> is a class type, constructors are
considered...</P></LI>

<LI><P><INS>Otherwise, if <TT>T</TT> is an enumeration with a fixed underlying
type (9.8.1 [<A href="https://wg21.link/dcl.enum">dcl.enum</A>]), the <I>initializer-list</I> has a single
element <TT>v</TT>, and the initialization is direct-list-initialization,
the object is initialized with the value <TT>T(v)</TT>
(7.6.1.4 [<A href="https://wg21.link/expr.type.conv">expr.type.conv</A>]); if a narrowing conversion is required to
convert v to the underlying type of <TT>T</TT>, the program is ill-formed.
[<I>Example:</I>...</INS></P></LI>

<LI><P>Otherwise, if the initializer list has a single element of
type <TT>E</TT>...</P></LI>

<LI><P>Otherwise, if <TT>T</TT> is a reference type...</P></LI>

<LI><P>
<DEL>Otherwise, if <TT>T</TT> is an enumeration with a fixed
underlying type...</DEL>
</P></LI>

</UL>

</BLOCKQUOTE>

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