<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">+cfe-dev<div class=""><br class=""></div><div class="">Hi Andrea,</div><div class=""><br class=""></div><div class="">I think you might get more luck asking on the cfe-dev mailing list.</div><div class=""><br class=""></div><div class="">George</div><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On May 15, 2018, at 1:15 PM, Andrea Arteaga via cfe-users <<a href="mailto:cfe-users@lists.llvm.org" class="">cfe-users@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Dear all,<br class=""><div class="gmail_quote"><div dir="ltr" class=""><div class="">Recently, my team suffered from a bug due to a double bad usage of C++.<br class=""><br class=""></div><div class="">We have a function returning a reference to an object:<br class=""><br class=""></div><div class=""> Object& GetObject();<br class=""><br class=""></div><div class="">Sometimes we use this function like this:<br class=""><br class=""></div><div class=""> auto obj = GetObject();<br class=""><br class=""></div><div class="">This triggers a copy of the object, which we really don't mean. The two problems are:<br class=""></div><div class="">1. Object does not delete the copy constructor, nor does it declare one. We have a policy of never using implicitly-declared constructors, we either use `=delete` or `=default`. Nevertheless we missed this class.<br class=""></div><div class="">2. A reference is demoted to a rvalue due to the usage of `auto` instead of `auto&`.<br class=""><br class=""></div><div class="">We would like clang to issue warnings in these two cases. The latter case does not really seem easy to warn about, but the former looks straightforward.<br class=""><br class=""></div><div class="">Does clang offer such warnings?<br class=""><br class=""></div><div class="">Thanks<span class="HOEnZb"><font color="#888888" class=""><br class=""></font></span></div><span class="HOEnZb"><font color="#888888" class=""><div class="">Andrea Arteaga <br class=""></div></font></span></div>
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