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    CWG Issue 1104</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="1104"></A><H4>1104.
  
Global-scope template arguments vs the <TT>&lt;:</TT> digraph
</H4>
<B>Section: </B>5.9&#160; [<A href="https://wg21.link/lex.digraph">lex.digraph</A>]
 &#160;&#160;&#160;

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

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

 <B>Date: </B>2010-08-02<BR><BR>


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

<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3296.html#US15">N3092 comment
  US&#160;15<BR></A>

<P>Passing a name qualified by the global scope operator <TT>::</TT> as
a template argument can inadvertently trigger recognition of the
<TT>&lt;:</TT> digraph, causing a syntax error.  This should be
handled by a lexical rule similar to the special treatment given to
<TT>&gt;&gt;</TT> so that <TT>&lt;::</TT> would be recognized as an
open angle-bracket followed by the scope-resolution operator.</P>

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

<P>Insert a bullet into the list in 5.5 [<A href="https://wg21.link/lex.pptoken">lex.pptoken</A>] paragraph
3 as follows:</P>

<BLOCKQUOTE>

If the input stream has been parsed into preprocessing tokens up to a
given character:

<UL>
<LI><P>if the next character begins a sequence of characters that
could be the prefix and initial double quote of a raw string literal,
such as <TT>R"</TT>, the next preprocessing token shall be a raw string
literal;</P></LI>

<LI><P><INS>otherwise, if the next three characters are
<TT>&lt;::</TT> and the subsequent character is neither <TT>:</TT> nor
<TT>&gt;</TT>, the <TT>&lt;</TT> is treated as a preprocessor token by
itself (and not as the first character of the alternative token
<TT>&lt;:</TT>);</INS></P></LI>

<LI><P>otherwise, the next preprocessing token is the longest
sequence...</P></LI>

</UL>

</BLOCKQUOTE>

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