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diff --git a/clang/docs/AutomaticReferenceCounting.html b/clang/docs/AutomaticReferenceCounting.html index 27d017c3171..74506b04b15 100644 --- a/clang/docs/AutomaticReferenceCounting.html +++ b/clang/docs/AutomaticReferenceCounting.html @@ -1,8 +1,10 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" + "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>Objective-C Automatic Reference Counting (ARC)</title> -<link type="text/css" rel="stylesheet" href="../menu.css" /> -<link type="text/css" rel="stylesheet" href="../content.css" /> +<link type="text/css" rel="stylesheet" href="../menu.css"> +<link type="text/css" rel="stylesheet" href="../content.css"> <style type="text/css"> /* Collapse the items in the ToC to the left. */ div#toc ul { @@ -26,7 +28,7 @@ div div div div h1 { margin: 1.12em 0 } span.term { font-style: italic; font-weight: bold } </style> -<script lang="javascript"> +<script type="text/javascript"> /// A little script to recursively build a table of contents. function buildTOC(div, toc, ancestry) { var children = div.childNodes; @@ -739,7 +741,7 @@ semantics as the respective operation would have on an <tt>void*</tt> lvalue with the same alignment and non-ownership qualification.</p> <p><span class="term">Reading</span> occurs when performing a -lvalue-to-rvalue conversion on an object lvalue. +lvalue-to-rvalue conversion on an object lvalue.</p> <ul> <li>For <tt>__weak</tt> objects, the current pointee is retained and @@ -749,10 +751,9 @@ release of the pointee.</li> <li>For all other objects, the lvalue is loaded with primitive semantics.</li> </ul> -</p> <p><span class="term">Assignment</span> occurs when evaluating -an assignment operator. The semantics vary based on the qualification: +an assignment operator. The semantics vary based on the qualification:</p> <ul> <li>For <tt>__strong</tt> objects, the new pointee is first retained; second, the lvalue is loaded with primitive semantics; third, the new @@ -771,11 +772,10 @@ stored into the lvalue using primitive semantics.</li> <li>For <tt>__autoreleasing</tt> objects, the new pointee is retained, autoreleased, and stored into the lvalue using primitive semantics.</li> </ul> -</p> <p><span class="term">Initialization</span> occurs when an object's lifetime begins, which depends on its storage duration. -Initialization proceeds in two stages: +Initialization proceeds in two stages:</p> <ol> <li>First, a null pointer is stored into the lvalue using primitive semantics. This step is skipped if the object @@ -784,7 +784,6 @@ is <tt>__unsafe_unretained</tt>.</li> evaluated and then assigned into the object using the usual assignment semantics.</li> </ol> -</p> <p><span class="term">Destruction</span> occurs when an object's lifetime ends. In all cases it is semantically equivalent to @@ -863,7 +862,7 @@ is left.</p> <p>A program is ill-formed if an expression of type <tt>T*</tt> is converted, explicitly or implicitly, to the type <tt>U*</tt>, where <tt>T</tt> and <tt>U</tt> have different ownership -qualification, unless: +qualification, unless:</p> <ul> <li><tt>T</tt> is qualified with <tt>__strong</tt>, <tt>__autoreleasing</tt>, or <tt>__unsafe_unretained</tt>, and @@ -876,9 +875,8 @@ qualification, unless: <li>the conversion is a well-formed <a href="#ownership.restrictions.pass_by_writeback">pass-by-writeback</a>.</li> </ul> -</p> -<p>The analogous rule applies to <tt>T&</tt> and <tt>U&</tt> in +<p>The analogous rule applies to <tt>T&</tt> and <tt>U&</tt> in Objective-C++.</p> <div class="rationale"><p>Rationale: these rules provide a reasonable @@ -933,7 +931,7 @@ where <tt>oq</tt> is an ownership qualifier, then the argument is a candidate for <span class="term">pass-by-writeback</span> if:</p> <ul> -<li><tt>oq</tt> is <tt>__strong</tt> or <tt>__weak</tt>, and +<li><tt>oq</tt> is <tt>__strong</tt> or <tt>__weak</tt>, and</li> <li>it would be legal to initialize a <tt>T __strong *</tt> with a <tt>U __strong *</tt>.</li> </ul> @@ -946,7 +944,7 @@ implicit conversion sequence not requiring a pass-by-writeback.</p> not have a legal form:</p> <ul> -<li><tt>&var</tt>, where <tt>var</tt> is a scalar variable of +<li><tt>&var</tt>, where <tt>var</tt> is a scalar variable of automatic storage duration with retainable object pointer type</li> <li>a conditional expression where the second and third operands are both legal forms</li> @@ -963,7 +961,7 @@ that the user will see confusing aliasing problems due to the implementation, below, where their store to the writeback temporary is not immediately seen in the original argument variable.</p></div> -<p>A pass-by-writeback is evaluated as follows: +<p>A pass-by-writeback is evaluated as follows:</p> <ol> <li>The argument is evaluated to yield a pointer <tt>p</tt> of type <tt>U oq *</tt>.</li> @@ -978,7 +976,7 @@ not immediately seen in the original argument variable.</p></div> actual call.</li> <li>After the call completes, the temporary is loaded with primitive semantics, and that value is assigned into <tt>*p</tt>.</li> -</ol></p> +</ol> <div class="rationale"><p>Rationale: this is all admittedly convoluted. In an ideal world, we would see that a local variable is @@ -1055,7 +1053,6 @@ it is implicitly qualified with <tt>__unsafe_unretained</tt>;</li> <li>otherwise, it is implicitly qualified with <tt>__autoreleasing</tt>.</li> </ul> -</p> <div class="rationale"><p>Rationale: <tt>__autoreleasing</tt> exists mostly for this case, the Cocoa convention for out-parameters. Since @@ -1101,7 +1098,7 @@ template argument was deduced or explicitly specified. </p> family</span>, which is a conventional set of behaviors ascribed to it by the Cocoa conventions.</p> -<p>A method is in a certain method family if: +<p>A method is in a certain method family if:</p> <ul> <li>it has a <tt>objc_method_family</tt> attribute placing it in that family; or if not that,</li> @@ -1109,7 +1106,7 @@ by the Cocoa conventions.</p> it in a different or no family, and</li> <li>its selector falls into the corresponding selector family, and</li> <li>its signature obeys the added restrictions of the method family.</li> -</ul></p> +</ul> <p>A selector is in a certain selector family if, ignoring any leading underscores, the first component of the selector either consists @@ -1132,7 +1129,7 @@ declares or contains a call to an <tt>init</tt> method whose return type is neither <tt>id</tt> nor a pointer to a super-class or sub-class of the declaring class (if the method was declared on a class) or the static receiver type of the call (if it was declared -on a protocol).</p> +on a protocol). <div class="rationale"><p>Rationale: there are a fair number of existing methods with <tt>init</tt>-like selectors which nonetheless don't @@ -1361,14 +1358,13 @@ clearer.</p></div> <p>A program is ill-formed if it contains a method definition, message send, or <tt>@selector</tt> expression for any of the following -selectors: +selectors:</p> <ul> <li><tt>autorelease</tt></li> <li><tt>release</tt></li> <li><tt>retain</tt></li> <li><tt>retainCount</tt></li> </ul> -</p> <div class="rationale"><p>Rationale: <tt>retainCount</tt> is banned because ARC robs it of consistent semantics. The others were banned @@ -1519,7 +1515,7 @@ retained during enumeration, and the collection itself cannot be synchronously modified. It can be overridden by explicitly qualifying the variable with <tt>__strong</tt>, which will make the variable mutable again and cause the loop to retain the objects it -encounters.</div> +encounters.</p></div> </div> @@ -1540,7 +1536,7 @@ retain during capture.</p> <p><tt>__block</tt> variables of retainable object owner type are moved off the stack by initializing the heap copy with the result of -moving from the stack copy.</tt></p> +moving from the stack copy.</p> <p>With the exception of retains done as part of initializing a <tt>__strong</tt> parameter variable or reading a <tt>__weak</tt> @@ -1555,7 +1551,7 @@ used only as an argument to a call.</p> <h1>Exceptions</h1> <p>By default in Objective C, ARC is not exception-safe for normal -releases: +releases:</p> <ul> <li>It does not end the lifetime of <tt>__strong</tt> variables when their scopes are abnormally terminated by an exception.</li> |
