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    CWG Issue 2594</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="2594"></A><H4>2594.
  
Disallowing a global function template <TT>main</TT>
</H4>
<B>Section: </B>6.10.3.1&#160; [<A href="https://wg21.link/basic.start.main">basic.start.main</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD6
 &#160;&#160;&#160;

 <B>Submitter: </B>Jim X
 &#160;&#160;&#160;

 <B>Date: </B>2022-06-06<BR>


<P>[Accepted at the July, 2022 meeting.]</P>

<P>Consider:</P>

<PRE>
  template&lt;class T&gt;
  int main(T) {}
</PRE>

<P>C++20 specified in 6.10.3.1 [<A href="https://wg21.link/basic.start.main#2">basic.start.main</A>] paragraph 2:</P>

<BLOCKQUOTE>

An implementation shall not predefine the main function. This function
shall not be overloaded.

</BLOCKQUOTE>

<P>While it is unclear what "overloaded" means when multiple
translation units are involved, it arguably disallowed function
templates called <TT>main</TT>.  This prohibition was removed with
P1787R6 (Declarations and where to find them).</P>

<P><B>Proposed resolution (approved by CWG 2022-06-17):</B></P>

<P>Change in 6.10.3.1 [<A href="https://wg21.link/basic.start.main#3">basic.start.main</A>] paragraph 3 and add bullets as
follows:</P>

<BLOCKQUOTE>

... A program that declares
<UL>
<LI>a variable <TT>main</TT> that belongs to the global scope, or</LI>

<LI>
<DEL>that declares</DEL> a function <TT>main</TT> that belongs to
the global scope and is attached to a named module, or</LI>

<LI><INS>a function template <TT>main</TT> that belongs to the global
scope, or</INS></LI>

<LI>
<DEL>that declares</DEL> an entity named <TT>main</TT> with C
language linkage (in any namespace)</LI>
</UL>
is ill-formed. The name <TT>main</TT> is not otherwise reserved.

</BLOCKQUOTE>

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