Hm. It's a bit much to put in the actual warning text, though, and most people who use clang for Objective-C won't be looking at Clang release notes anyway. Maybe I can try to put it through in our internal documentation (what appears on developer.apple.com).
Jordan On Jul 9, 2012, at 10:06 , Jean-Daniel Dupas <[email protected]> wrote: > While this is just a warning now, I found the comment in the release note > very helpful to understand why we should never do it. > > Le 9 juil. 2012 à 18:54, Jordan Rose a écrit : > >> Author: jrose >> Date: Mon Jul 9 11:54:44 2012 >> New Revision: 159939 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=159939&view=rev >> Log: >> Downgrade the "direct comparison" error for ObjC literals to a warning. >> >> Chris pointed out that while the comparison is certainly problematic >> and does not have well-defined behavior, it isn't any worse than some >> of the other abuses that we merely warn about and doesn't need to make >> the compilation fail. >> >> Revert the release notes change (r159766) now that this is just a new >> warning. >> >> Modified: >> cfe/trunk/docs/ReleaseNotes.html >> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td >> cfe/trunk/lib/Sema/SemaExpr.cpp >> cfe/trunk/test/FixIt/objc-literals.m >> cfe/trunk/test/SemaObjC/objc-literal-comparison.m >> >> Modified: cfe/trunk/docs/ReleaseNotes.html >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/ReleaseNotes.html?rev=159939&r1=159938&r2=159939&view=diff >> ============================================================================== >> --- cfe/trunk/docs/ReleaseNotes.html (original) >> +++ cfe/trunk/docs/ReleaseNotes.html Mon Jul 9 11:54:44 2012 >> @@ -218,21 +218,7 @@ >> <h3 id="objcchanges">Objective-C Language Changes in Clang</h3> >> <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >> --> >> >> -<ul> >> - <li> >> - <p>It is now an error to compare against the addresses of Objective-C >> - literals. This is usually a simple mistake (using <code>==</code> >> instead >> - of <code>-isEqual:</code>), and the result depends on the >> implementation >> - of the various literals, none of which are guaranteed to be uniqued >> or >> - always newly-allocated.</p> >> - <p>In the past, we allowed comparisons against literal strings >> - (<code>@"..."</code>), since they are currently uniqued across >> - translation units at link time. This is an implementation detail and >> - should not be relied upon. If you are using such code, please use >> global >> - string constants instead (<code>NSString * const MyConst = >> @"..."</code>) >> - or use <code>-isEqual:</code>.</p> >> - </li> >> -</ul> >> +<p>...</p> _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
