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    CWG Issue 366</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="366"></A><H4>366.
  
String literal allowed in integral constant expression?
</H4>
<B>Section: </B>7.7&#160; [<A href="https://wg21.link/expr.const">expr.const</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD1
 &#160;&#160;&#160;

 <B>Submitter: </B>Martin v. Loewis
 &#160;&#160;&#160;

 <B>Date: </B>29 July 2002<BR>


<P>[Voted into WP at October 2003 meeting.]</P>

<P>According to 15.2 [<A href="https://wg21.link/cpp.cond#1">cpp.cond</A>] paragraph 1, the if-group</P>
<PRE>
#if "Hello, world"
</PRE>
<P>is well-formed, since it is an integral constant expression.
Since that may not be obvious, here is why:</P>

<P>7.7 [<A href="https://wg21.link/expr.const#1">expr.const</A>] paragraph 1 says that an integral constant
expression may involve literals (5.13 [<A href="https://wg21.link/lex.literal">lex.literal</A>]);
"Hello, world" is a literal. It restricts
operators to not use certain type conversions; this expression does
not use type conversions. It further disallows functions, class
objects, pointers, ... - this expression is none of those, since it
is an array.</P>

<P>However, 15.2 [<A href="https://wg21.link/cpp.cond#6">cpp.cond</A>] paragraph 6 does not explain what
to do with this if-group, since
the expression evaluates neither to false(zero) nor true(non-zero).</P>

<P><B>Proposed resolution (October 2002):</B></P>

<P>Change the beginning of the second sentence of
7.7 [<A href="https://wg21.link/expr.const#1">expr.const</A>] paragraph 1 which currently reads
<BLOCKQUOTE>
An <I>integral constant-expression</I> can involve only literals
(5.13 [<A href="https://wg21.link/lex.literal">lex.literal</A>]), ...
</BLOCKQUOTE>
to say
<BLOCKQUOTE>
An <I>integral constant-expression</I> can involve only literals of
arithmetic types (5.13 [<A href="https://wg21.link/lex.literal">lex.literal</A>],
6.9.2 [<A href="https://wg21.link/basic.fundamental">basic.fundamental</A>]), ...
</BLOCKQUOTE>
</P>

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