<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;"><br><div><div>On May 22, 2014, at 1:58 PM, Richard Smith <<a href="mailto:richard@metafoo.co.uk">richard@metafoo.co.uk</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Thu, May 22, 2014 at 1:48 PM, jahanian <span dir="ltr"><<a href="mailto:fjahanian@apple.com" target="_blank">fjahanian@apple.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><div class=""><div>On May 22, 2014, at 11:40 AM, Richard Smith <<a href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>> wrote:</div>
<br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br></div><div>Another problem with our current model is that we build a broken redeclaration chain (the local declaration is marked as being a redeclaration of the implicitly-declared builtin, which it isn't). This leads to other bugs; for instance:</div>
<div><br></div><div>void f() { int memcpy(void); } void g() { memcpy(0,0,0); }<br></div><div><br></div><div>... misses the "implicitly declaring library function" warning.</div></div></div></div></blockquote><div>
<br></div></div>Interesting point. Currently, we create a built-in declaration of “memcpy” and make local declaration as its redeclaration.</div><div>Should we just not create the implicit built-in declaration when user declaration is local? If we do this,</div>
<div>then the missing warning you mentioned will come out (and my bug gets fixed). But, we will miss the warning </div><div>about "<font face="Menlo"><span style="font-size:11px">incompatible redeclaration of library function ‘memcpy’” on local “redeclaration”.</span></font></div>
<div><font face="Menlo"><span style="font-size:11px">Which, I think, is ok as it is no longer a redeclaration.</span></font></div><div><font face="Menlo"><span style="font-size:11px">Am I reading you correctly?</span></font></div>
</div></blockquote><div><br></div><div>I think we should still produce the "incompatible redeclaration of library function" warning. I think it'd be better if we didn't create the implicit built-in declaration at all, but I don't think it should matter whether the declaration is local. If I write a non-local declaration:</div></div></div></div></blockquote><div><br></div>I have an experimental patch which does not create the implicit built-in declaration at all. It fixes my original bug and also produces the error</div><div>for the test case that you sent earlier:</div><div><br></div><div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:1:16: warning: incompatible redeclaration of library function 'memcpy'</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">void f() { int memcpy(void); } </div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"> ^</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:1:16: note: 'memcpy' is a builtin with type 'void *(void *, const void *, unsigned long)'</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:3:12: warning: use of out-of-scope declaration of 'memcpy'</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">void g() { memcpy(0,0,0); }</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"> ^</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:1:16: note: previous declaration is here</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">void f() { int memcpy(void); } </div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"> ^</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:3:19: error: too many arguments to function call, expected 0, have 3</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">void g() { memcpy(0,0,0); }</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"> ~~~~~~ ^~~~~</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">fix.c:1:12: note: 'memcpy' declared here</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">void f() { int memcpy(void); } </div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"> ^</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">2 warnings and 1 error generated.</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"><br></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">But there are several issues remaining.</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"><br></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;">1) This patch issues a diagnostic only once. So, for example, for this test:</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;"><div style="margin: 0px;">void f() { int memcpy(void); } </div><div style="margin: 0px;">void g() { int memcpy(void); }</div><div style="margin: 0px;"><br></div><div style="margin: 0px;">or:</div><div style="margin: 0px;"><div style="margin: 0px;">void f() { int memcpy(void); } </div><div style="margin: 0px;">int memcpy(void) {}</div></div><div style="margin: 0px;"><br></div><div style="margin: 0px;">We now issue the warning on first declaration of memcpy. Reason being that after 1st declaration we</div><div style="margin: 0px;">treat memcpy as a user declaration and the 2nd declaration will not be seen as built-in</div><div style="margin: 0px;">(you mentioned that there is a Builtin context I can check without requiring BuiltinID. But I</div><div style="margin: 0px;">cannot find it).</div><div style="margin: 0px;"><br></div><div style="margin: 0px;">Many tests had to be modified mainly because global declaration of builtin functions in these tests are</div><div style="margin: 0px;">incorrect and this patch catches it. But this also points that projects will break.</div><div style="margin: 0px;"><br></div><div style="margin: 0px;">Patch is attached for your further comments.</div><div style="margin: 0px;">- Thanks, Fariborz</div><div style="margin: 0px;"></div></div></div></body></html>