<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">On Aug 5, 2013, at 1:58 PM, Richard Smith <<a href="mailto:richard@metafoo.co.uk">richard@metafoo.co.uk</a>> wrote:<br><div><blockquote type="cite"><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">On Mon, Aug 5, 2013 at 1:47 PM, John McCall<span class="Apple-converted-space"> </span><span dir="ltr"><<a href="mailto:rjmccall@apple.com" target="_blank">rjmccall@apple.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div style="word-wrap: break-word;"><div><div class="h5">On Aug 5, 2013, at 1:42 PM, Richard Smith <<a href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>> wrote:<br><div><blockquote type="cite"><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">On Mon, Aug 5, 2013 at 1:19 PM, John McCall<span> </span><span dir="ltr"><<a href="mailto:rjmccall@apple.com" target="_blank">rjmccall@apple.com</a>></span><span> </span>wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div style="word-wrap: break-word;"><div>On Aug 5, 2013, at 11:49 AM, Richard Smith <<a href="mailto:richard-llvm@metafoo.co.uk" target="_blank">richard-llvm@metafoo.co.uk</a>> wrote:<br></div><div><div><blockquote type="cite"><div style="font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Author: rsmith<br>Date: Mon Aug 5 13:49:43 2013<br>New Revision: 187735<br><br>URL:<span> </span><a href="http://llvm.org/viewvc/llvm-project?rev=187735&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=187735&view=rev</a><br>Log:<br>Implement C++'s restrictions on the type of an expression passed to a vararg<br>function: it can't be 'void' and it can't be an initializer list. We give a<br>hard error for these rather than treating them as undefined behavior (we can<br>and probably should do the same for non-POD types in C++11, but as of this<br>change we don't).<br></div></blockquote><div><br></div></div><div>Doesn’t this change SFINAE behavior? </div></div></div></blockquote></div><div><br></div><div>I'm not sure whether your "this" binds to the change or to the parenthetical in the comment.</div><div><br></div><div>For the former, yes, and it's supposed to: 5.2.2/7 says the program is ill-formed.</div><div><br></div><div>For the latter, this is "conditionally-supported with implementation-defined semantics". Per 1.4/2, this means "when the implementation does not support that construct, a conforming implementation shall issue at least one diagnostic message", and the intent is that implementations treat such constructs as being ill-formed if they do not support them. Our current implementation is conforming, if unfriendly. FWIW, g++ rejects such constructs.</div></div></blockquote></div><br></div></div><div>Are you sure it doesn’t just reject them if potentially evaluated? Overloads where one option is (...) are pretty much standard. </div></div></blockquote></div><br><div>Yes, indeed it does. Somewhat amusingly, it has the same behavior for passing {} through an ellipsis, but gives an error for passing 'void' through an ellipsis even in an unevaluated context.</div></div></blockquote></div><br><div>Heh. I agreeing that unconditionally erroring on passing void and {} through ... is the right thing to do.</div><div><br></div><div>John.</div></body></html>