<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 12 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
        {font-family:"Cambria Math";
        panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
        {font-family:Calibri;
        panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
        {font-family:Tahoma;
        panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
        {margin:0in;
        margin-bottom:.0001pt;
        font-size:12.0pt;
        font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
        {mso-style-priority:99;
        color:blue;
        text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
        {mso-style-priority:99;
        color:purple;
        text-decoration:underline;}
span.EmailStyle17
        {mso-style-type:personal-reply;
        font-family:"Calibri","sans-serif";
        color:#1F497D;}
.MsoChpDefault
        {mso-style-type:export-only;}
@page WordSection1
        {size:8.5in 11.0in;
        margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
        {page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Maybe just “__cpp_constexpr11” and “__cpp_constexpr14”?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> features-bounces@open-std.org [mailto:features-bounces@open-std.org]
<b>On Behalf Of </b>Richard Smith<br>
<b>Sent:</b> Monday, June 03, 2013 2:20 PM<br>
<b>To:</b> Nelson, Clark<br>
<b>Cc:</b> features@isocpp.open-std.org (features@open-std.org)<br>
<b>Subject:</b> Re: [SG10] Generalized/relaxed const. expr.<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On Mon, Jun 3, 2013 at 4:52 PM, Nelson, Clark <<a href="mailto:clark.nelson@intel.com" target="_blank">clark.nelson@intel.com</a>> wrote:<o:p></o:p></p>
<div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<p class="MsoNormal">I wanted to get feedback from authors of proposals on macro names to represent their features as soon as possible; I started by turning Tom's list of C++11 features into a table in the same style as what we already have for C++14. (As
background, please remember that, to the greatest degree that makes sense, I'm tending to use words from the title of the proposal paper to name the feature-test macro.)<br>
<br>
The title of N2235, by which "constexpr" was introduced into C++, was basically "Generalized Constant Expressions". So the more or less mindless name of the macro might be "__cpp_generalized_constant".<br>
<br>
Whereas N3652, which eliminates the constraints on a constexpr function, is entitled, in part, "Relaxing constraints on constexpr functions"; hence "__cpp_relaxed_constexpr".<br>
<br>
It hardly seems likely that we will want to use the word "generalized" as part of two different macro names regarding constexpr -- but we could conceivably decide that this is a case for changing the value of a macro, instead of defining a new one.<br>
<br>
>From my perspective as an implementer, the change that was voted into C++14 doesn't seem minor or subtle, but I guess opinions might differ.<br>
<br>
Comments?<o:p></o:p></p>
</blockquote>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I don't think either *generalized* or *relaxed* is sufficiently future-proof. What happens if C++17 generalizes constants further or relaxes more constexpr restrictions? And do we really want people to need to remember which features were
"generalized" and which were "relaxed"? More generally, I don't think we should use names which describe a difference between C++ version N and C++ version N+1; instead, we should pick names which describe the features objectively (names which still make sense
as features of C++ version aleph_0).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">So, some strawman proposals:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">1) For N2235, use __cpp_constexpr (emphasizing the new keyword)<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">For N3652, use __cpp_constexpr_statements (emphasizing that this is an extension of __cpp_constexpr, and that the primary change is that it permits almost any statements in constexpr functions)<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">2) N2235 has #define __cpp_constexpr 1, and N3652 has #define __cpp_constexpr 2.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">3) N2235 has #define __cpp_constexpr 201103L and N3652 has #define __cpp_constexpr 2014xxL.<o:p></o:p></p>
</div>
</div>
</div>
</div>
</body>
</html>