<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">This is implementation-defined, not undefined. C99 6.3.1.3p3:<div class=""><br class=""></div><div class=""> Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised.<br class=""><div class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span class="Apple-style-span" style="border-collapse: separate; font-variant-ligatures: normal; font-variant-east-asian: normal; font-variant-position: normal; line-height: normal; border-spacing: 0px; -webkit-text-decorations-in-effect: none;"><br class="Apple-interchange-newline">Jess</span></div></div></div></div></div>
</div>
<div><br class=""><blockquote type="cite" class=""><div class="">On 21 Jan 2022, at 07:16, Craig Topper via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">I'm not sure that is undefined behavior, but it is caught by -fsanitize=integer<div class=""><br clear="all" class=""><div class=""><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">~Craig</div></div><br class=""></div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 20, 2022 at 11:06 PM phy coder via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto" class="">And if I'm wrong or misunderstand something then please let me know.</div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jan 21, 2022, 12:00 phy coder <<a href="mailto:coderphy3@gmail.com" target="_blank" class="">coderphy3@gmail.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr" class=""><div class="">I'm not sure if this is undefined behavior or not and it may be discussed before or not. I was testing some random code snippets to try "-fsanitize=undefined" but in this example:<br class=""></div><div class=""><br class=""></div><div class=""><div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:"Droid Sans Mono","monospace",monospace,"Droid Sans Fallback";font-weight:normal;font-size:20px;line-height:27px;white-space:pre-wrap" class=""><div class=""><span style="color:rgb(197,134,192)" class="">#include</span><span style="color:rgb(206,145,120)" class=""><iostream></span></div><br class=""><div class=""><span style="color:rgb(86,156,214)" class="">char</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(220,220,170)" class="">func</span><span style="color:rgb(212,212,212)" class="">(</span><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">a</span><span style="color:rgb(212,212,212)" class="">, </span><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">b</span><span style="color:rgb(212,212,212)" class="">) {</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">sum</span><span style="color:rgb(212,212,212)" class=""> = </span><span style="color:rgb(156,220,254)" class="">a</span><span style="color:rgb(212,212,212)" class="">+</span><span style="color:rgb(156,220,254)" class="">b</span><span style="color:rgb(212,212,212)" class="">;</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(197,134,192)" class="">return</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">sum</span><span style="color:rgb(212,212,212)" class=""> ;</span></div><div class=""><span style="color:rgb(212,212,212)" class="">}</span></div><br class=""><div class=""><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(220,220,170)" class="">main</span><span style="color:rgb(212,212,212)" class="">() {</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">n</span><span style="color:rgb(212,212,212)" class="">;</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(86,156,214)" class="">char</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">s</span><span style="color:rgb(212,212,212)" class=""> = </span><span style="color:rgb(220,220,170)" class="">func</span><span style="color:rgb(212,212,212)" class="">(</span><span style="color:rgb(181,206,168)" class="">100</span><span style="color:rgb(212,212,212)" class="">,</span><span style="color:rgb(181,206,168)" class="">100</span><span style="color:rgb(212,212,212)" class="">);</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(86,156,214)" class="">int</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">t</span><span style="color:rgb(212,212,212)" class=""> = </span><span style="color:rgb(220,220,170)" class="">func</span><span style="color:rgb(212,212,212)" class="">(</span><span style="color:rgb(181,206,168)" class="">100</span><span style="color:rgb(212,212,212)" class="">,</span><span style="color:rgb(181,206,168)" class="">100</span><span style="color:rgb(212,212,212)" class="">);</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(78,201,176)" class="">std</span><span style="color:rgb(212,212,212)" class="">::</span><span style="color:rgb(156,220,254)" class="">cout</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(220,220,170)" class=""><<</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(206,145,120)" class="">"hello"</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(220,220,170)" class=""><<</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">s</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(220,220,170)" class=""><<</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(156,220,254)" class="">t</span><span style="color:rgb(212,212,212)" class="">;</span></div><div class=""><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(197,134,192)" class="">return</span><span style="color:rgb(212,212,212)" class=""> </span><span style="color:rgb(181,206,168)" class="">0</span><span style="color:rgb(212,212,212)" class="">;</span></div><br class=""><div class=""><span style="color:rgb(212,212,212)" class="">}</span></div><div class=""><span style="color:rgb(212,212,212)" class=""><br class=""></span></div></div></div><div class="">I was expecting some kind of undefined behavior here because of some overflowing the char return type with integer return type. But "-fsanitize=undefined" is not able to catch this . And I got the output this : hello�-56 <br class=""></div><div class="">Kinda weird for me . <br class=""></div></div>
</blockquote></div>
_______________________________________________<br class="">
cfe-dev mailing list<br class="">
<a href="mailto:cfe-dev@lists.llvm.org" target="_blank" class="">cfe-dev@lists.llvm.org</a><br class="">
<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" rel="noreferrer" target="_blank" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><br class="">
</blockquote></div>
_______________________________________________<br class="">cfe-dev mailing list<br class=""><a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a><br class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev<br class=""></div></blockquote></div><br class=""></div></body></html>