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    CWG Issue 1195</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="1195"></A><H4>1195.
  
References to non-literal types in constexpr functions
</H4>
<B>Section: </B>9.2.6&#160; [<A href="https://wg21.link/dcl.constexpr">dcl.constexpr</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>Daniel Kr&#252;gler
 &#160;&#160;&#160;

 <B>Date: </B>2010-09-05<BR>


<P>[Voted into the WP at the March, 2011 meeting as part of paper N3277.]</P>



<P>9.2.6 [<A href="https://wg21.link/dcl.constexpr#3">dcl.constexpr</A>] paragraph 3 is overly restrictive
in requiring that reference parameter and return types of a constexpr
function or constructor must refer to a literal type.
7.7 [<A href="https://wg21.link/expr.const#2">expr.const</A>] paragraph 2 already prevents any
problematic uses of lvalues of non-literal types, and it permits
use of pointers to non-literal types as address constants.  The
same should be permitted via reference parameters and return types
of constexpr functions.</P>

<P>(See also <A HREF="1194.html">issue 1194</A>.)</P>

<P><B>Proposed resolution (November, 2010):</B></P>

<OL>
<LI><P>Change 6.9 [<A href="https://wg21.link/basic.types#10">basic.types</A>] paragraph 10 as follows:</P></LI>

<BLOCKQUOTE>

<P>A type is a <I>literal type</I> if it is:</P>

<UL>
<LI><P>a scalar type; or</P></LI>

<LI><P><INS>a reference type; or</INS></P></LI>

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

</UL>

</BLOCKQUOTE>

<LI><P>Change 9.2.6 [<A href="https://wg21.link/dcl.constexpr#3">dcl.constexpr</A>] paragraph 3 as follows:</P></LI>

<BLOCKQUOTE>

<P>The definition of a constexpr function shall satisfy the following
constraints:</P>

<UL>
<LI><P>it shall not be virtual (11.7.3 [<A href="https://wg21.link/class.virtual">class.virtual</A>])</P></LI>

<LI><P>its return type shall be a literal type <DEL>or a reference to
literal type</DEL>
</P></LI>

<LI><P>each of its parameter types shall be a literal type <DEL>or a
reference to literal type</DEL>
</P></LI>

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

</UL>

</BLOCKQUOTE>

<LI><P>Change 9.2.6 [<A href="https://wg21.link/dcl.constexpr#4">dcl.constexpr</A>] paragraph 4 as follows:</P></LI>

<BLOCKQUOTE>

<P>The definition of a constexpr constructor shall satisfy the
following constraints:</P>

<UL>
<LI><P>each of its parameter types shall be a literal type <DEL>or a
reference to literal type</DEL>;</P></LI>

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

</UL>

</BLOCKQUOTE>

</OL>

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