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    CWG Issue 717</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="717"></A><H4>717.
  
Unintentional restrictions on the use of <TT>thread_local</TT>
</H4>
<B>Section: </B>9.2.2&#160; [<A href="https://wg21.link/dcl.stc">dcl.stc</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Clark Nelson
 &#160;&#160;&#160;

 <B>Date: </B>17 September, 2008<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3086.html#US36">N2800 comment
  US&#160;36<BR></A>

<P>[Voted into WP at October, 2009 meeting.]</P>

<P>The current wording unintentionally restricts the use of the
<TT>thread_local</TT> specifier in two contexts: block-scope
extern variable declarations and static data members.  These
restrictions are in conflict with 9.2.2 [<A href="https://wg21.link/dcl.stc#1">dcl.stc</A>] paragraph 1.
</P>

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

<P>Change 9.2.2 [<A href="https://wg21.link/dcl.stc#4">dcl.stc</A>] paragraph 4 as follows:</P>

<BLOCKQUOTE>

 The <TT>thread_local</TT> specifier shall be applied only to the
names of objects or references of namespace scope<DEL>
and</DEL><INS>,</INS> to the names of objects or references of block
scope that also specify <INS><TT>extern</TT> or</INS>
<TT>static</TT><INS>, and to the names of static data
members</INS>. It specifies that the named object or reference has
thread storage duration (6.8.6.3 [<A href="https://wg21.link/basic.stc.thread">basic.stc.thread</A>]).

</BLOCKQUOTE>

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