<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 612</TITLE>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<STYLE TYPE="text/css">
  INS { text-decoration:none; font-weight:bold; background-color:#A0FFA0 }
  .INS { text-decoration:none; background-color:#D0FFD0 }
  DEL { text-decoration:line-through; background-color:#FFA0A0 }
  .DEL { text-decoration:line-through; background-color: #FFD0D0 }
  @media (prefers-color-scheme: dark) {
    HTML { background-color:#202020; color:#f0f0f0; }
    A { color:#5bc0ff; }
    A:visited { color:#c6a8ff; }
    A:hover, a:focus { color:#afd7ff; }
    INS { background-color:#033a16; color:#aff5b4; }
    .INS { background-color: #033a16; }
    DEL { background-color:#67060c; color:#ffdcd7; }
    .DEL { background-color:#67060c; }
  }
  SPAN.cmnt { font-family:Times; font-style:italic }
</STYLE>
</HEAD>
<BODY>
<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="612"></A><H4>612.
  
Requirements on a conforming implementation
</H4>
<B>Section: </B>6.10.1&#160; [<A href="https://wg21.link/intro.execution">intro.execution</A>]
 &#160;&#160;&#160;

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

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

 <B>Date: </B>23 January 2007<BR>


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

<P>The execution requirements on a conforming implementation are
described twice in the Standard, once in 6.10.1 [<A href="https://wg21.link/intro.execution">intro.execution</A>]
paragraphs 5-6 and again in paragraph 11.  These descriptions differ
in at least a couple of important ways:</P>

<P>The most significant discrepancy has to do with the way output is
described. In paragraph 11, the least requirements are described in
terms of data written at program termination, clearly allowing
arbitrary buffering, whereas in paragraph 6, the observable behavior
is described in terms of calls to I/O functions.  For example, there
are compilers which transform a call to printf with a single argument
into a call to fputs.  That's valid under paragraph 11, but not under
paragraph 6.</P>

<P>Also, in paragraph 6, volatile accesses and I/O operations are
included in a single sequence, suggesting that they are equally
constrained by sequencing requirements, whereas in paragraph 11, they
are clearly not.</P>

<P>There are also editorial discrepancies that should be cleaned
up.</P>

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

<P>The resolution of <A HREF="785.html">issue 785</A> also
resolves this issue.</P>

<BR><BR>
</BODY>
</HTML>
