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    CWG Issue 811</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="811"></A><H4>811.
  
Unclear implications of const-qualification
</H4>
<B>Section: </B>9.2.9.2&#160; [<A href="https://wg21.link/dcl.type.cv">dcl.type.cv</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD2
 &#160;&#160;&#160;

 <B>Submitter: </B>UK
 &#160;&#160;&#160;

 <B>Date: </B>3 March, 2009<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3086.html#UK89">N2800 comment
  UK&#160;89<BR></A>

<P>[Voted into WP at March, 2010 meeting.]</P>

<P>The normative text in 9.2.9.2 [<A href="https://wg21.link/dcl.type.cv#2">dcl.type.cv</A>] paragraph 2 reads,</P>

<BLOCKQUOTE>

An object declared in namespace scope with a const-qualified type has
internal linkage unless it is explicitly declared <TT>extern</TT> or
unless it was previously declared to have external linkage.  A
variable of non-volatile const-qualified integral or enumeration type
initialized by an integral constant expression can be used in integral
constant expressions (7.7 [<A href="https://wg21.link/expr.const">expr.const</A>]).

</BLOCKQUOTE>

<P>These two sentences parallel the specifications of
9.2.2 [<A href="https://wg21.link/dcl.stc#7">dcl.stc</A>] paragraph 7 and 7.7 [<A href="https://wg21.link/expr.const">expr.const</A>].
However, the passages are not identical, leading to questions about
whether the meanings are the same.</P>

<P><B>Proposed resolution (October, 2009):</B></P>

<P>Change 9.2.9.2 [<A href="https://wg21.link/dcl.type.cv#2">dcl.type.cv</A>] paragraph 2 as follows:</P>

<BLOCKQUOTE>

<DEL>An object declared in namespace scope with a const-qualified type
has internal linkage unless it is explicitly declared <TT>extern</TT>
or unless it was previously declared to have external linkage.  A
variable of non-volatile const-qualified integral or enumeration type
initialized by an integral constant expression can be used in integral
constant expressions (7.7 [<A href="https://wg21.link/expr.const">expr.const</A>]).</DEL> [<I>Note:</I>
<INS>Declaring a variable <TT>const</TT> can affect its linkage
(9.2.2 [<A href="https://wg21.link/dcl.stc">dcl.stc</A>]) and its usability in constant expressions
(7.7 [<A href="https://wg21.link/expr.const">expr.const</A>]).  As</INS> <DEL>as</DEL> described in
9.5 [<A href="https://wg21.link/dcl.init">dcl.init</A>], the definition of an object or subobject of
const-qualified type must specify an initializer or be subject to
default-initialization. &#8212;<I>end note</I>]

</BLOCKQUOTE>

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