Author: george.karpenkov Date: Mon Oct 22 18:30:45 2018 New Revision: 344991
URL: http://llvm.org/viewvc/llvm-project?rev=344991&view=rev Log: [analyzer] [www] Drop references to GC mode, which was deprecated years ago Differential Revision: https://reviews.llvm.org/D53302 Removed: cfe/trunk/www/analyzer/images/example_cf_returns_retained_gc.png Modified: cfe/trunk/www/analyzer/annotations.html Modified: cfe/trunk/www/analyzer/annotations.html URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/analyzer/annotations.html?rev=344991&r1=344990&r2=344991&view=diff ============================================================================== --- cfe/trunk/www/analyzer/annotations.html (original) +++ cfe/trunk/www/analyzer/annotations.html Mon Oct 22 18:30:45 2018 @@ -152,16 +152,6 @@ analyzer typically does not make any ass is returned retained. Explicitly adding the 'ns_returns_retained' attribute to C functions allows the analyzer to perform extra checking.</p> -<p><b>Important note when using Garbage Collection</b>: Note that the analyzer -interprets this attribute slightly differently when using Objective-C garbage -collection (available on Mac OS 10.5+). When analyzing Cocoa code that uses -garbage collection, "alloc" methods are assumed to return an object -that is managed by the garbage collector (and thus doesn't have a retain count -the caller must balance). These same assumptions are applied to methods or -functions annotated with 'ns_returns_retained'. If you are returning a Core -Foundation object (which may not be managed by the garbage collector) you should -use 'cf_returns_retained'.</p> - <p><b>Example</b></p> <pre class="code_example"> @@ -243,16 +233,15 @@ that is functionally equivalent to the o <p><b>Placing on Objective-C methods</b>: With respect to Objective-C methods., this attribute is identical in its behavior and usage to 'ns_returns_retained' except for the distinction of returning a Core Foundation object instead of a -Cocoa object. This distinction is important for two reasons:</p> +Cocoa object. -<ul> - <li>Core Foundation objects are not automatically managed by the Objective-C - garbage collector.</li> - <li>Because Core Foundation is a C API, the analyzer cannot always tell that a - pointer return value refers to a Core Foundation object. In contrast, it is - trivial for the analyzer to recognize if a pointer refers to a Cocoa object - (given the Objective-C type system). -</ul> +This distinction is important for the following reason: +as Core Foundation is a C API, +the analyzer cannot always tell that a pointer return value refers to a +Core Foundation object. +In contrast, it is +trivial for the analyzer to recognize if a pointer refers to a Cocoa object +(given the Objective-C type system). <p><b>Placing on C functions</b>: When placing the attribute 'cf_returns_retained' on the declarations of C functions, the analyzer @@ -264,17 +253,11 @@ interprets the function as:</p> contained the keywords "create" or "copy". This means the returned object as a +1 retain count that must be released by the caller, either by sending a <tt>release</tt> message (via toll-free bridging to an Objective-C -object pointer), calling <tt>CFRelease</tt> (or similar function), or using -<tt>CFMakeCollectable</tt> to register the object with the Objective-C garbage -collector.</li> +object pointer), or calling <tt>CFRelease</tt> or a similar function.</li> </ol> <p><b>Example</b></p> -<p>In this example, observe the difference in output when the code is compiled -to not use garbage collection versus when it is compiled to only use garbage -collection (<tt>-fobjc-gc-only</tt>).</p> - <pre class="code_example"> <span class="command">$ cat test.m</span> $ cat test.m @@ -322,15 +305,6 @@ CFDateRef returnsRetainedCFDate() { <img src="images/example_cf_returns_retained.png" alt="example returns retained"> -<p>When the above code is compiled using Objective-C garbage collection (i.e., -code is compiled with the flag <tt>-fobjc-gc</tt> or <tt>-fobjc-gc-only</tt>), -<tt>scan-build</tt> produces both the above error (with slightly different text -to indicate the code uses garbage collection) as well as the following warning, -which indicates a leak that occurs <em>only</em> when using garbage -collection:</p> - -<img src="images/example_cf_returns_retained_gc.png" alt="example returns retained gc"> - <h4 id="attr_cf_returns_not_retained">Attribute 'cf_returns_not_retained' (Clang-specific)</h4> @@ -372,13 +346,6 @@ static analyzer that a <tt>release</tt> parameter upon completion of the call to the given function or method. The Foundation framework defines a macro <b><tt>NS_RELEASES_ARGUMENT</tt></b> that is functionally equivalent to the <tt>NS_CONSUMED</tt> macro shown below.</p> - -<p><b>Important note when using Garbage Collection</b>: Note that the analyzer -essentially ignores this attribute when code is compiled to use Objective-C -garbage collection. This is because the <tt>release</tt> message does nothing -when using GC. If the underlying function/method uses something like -<tt>CFRelease</tt> to decrement the reference count, consider using -the <a href="#attr_cf_consumed">cf_consumed</a> attribute instead.</p> <p><b>Example</b></p> @@ -432,10 +399,7 @@ to the given function or method. The Cor <b><tt>CF_RELEASES_ARGUMENT</tt></b> that is functionally equivalent to the <tt>CF_CONSUMED</tt> macro shown below.</p> -<p>Operationally this attribute is nearly identical to 'ns_consumed' with the -main difference that the reference count decrement still occurs when using -Objective-C garbage collection (which is important for Core Foundation types, -which are not automatically garbage collected).</p> +<p>Operationally this attribute is nearly identical to 'ns_consumed'.</p> <p><b>Example</b></p> Removed: cfe/trunk/www/analyzer/images/example_cf_returns_retained_gc.png URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/analyzer/images/example_cf_returns_retained_gc.png?rev=344990&view=auto ============================================================================== Binary file - no diff available. _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
