clang/www/analyzer/implicit_checks.html

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  20 <h1>Implicit Checkers</h1>
  21 Even though the implicit checkers do not produce any warnings, they are used to
  22 support the analyzer core and model known APIs. See also
  23 <a href = "available_checks.html">Default Checkers</a>
  24 and <a href = "alpha_checks.html">Experimental (Alpha) Checkers</a>.
  25 <ul>
  26 <li><a href="#core_implicit_checkers">Core Implicit Checkers</a></li>
  27 <li><a href="#osx_implicit_checkers">OS X Implicit Checkers</a></li>
  28 </ul>
  29
  30 <!-- =========================== core implicit =========================== -->
  31 <h3 id="core_implicit_checkers">Core Implicit Checkers</h3>
  32 <table class="checkers">
  33 <colgroup><col class="namedescr"><col class="example"></colgroup>
  34 <thead><tr><td>Name, Description</td><td>Example</td></tr></thead>
  35
  36 <tbody>
  37 <tr><td><div class="namedescr expandable"><span class="name">
  38 core.DynamicTypePropagation</span><span class="lang">
  39 (C++, ObjC)</span><div class="descr">
  40 Generate dynamic type information.</div></div></td>
  41 <td><div class="exampleContainer expandable">
  42 <div class="example"><pre>
  43 // C++
  44 class A {
  45 public:
  46   A(int x) {}
  47   virtual int foo();
  48 };
  49
  50 class B: public A {
  51 public:
  52   B()
  53   :A(foo())
  54   // DynamicTypeInfo for 'this' rigion will wrap type 'A'
  55   // unless the base constructor call expression is processed
  56   {}
  57   virtual int foo();
  58 };
  59 </pre></div><div class="separator"></div>
  60 <div class="example"><pre>
  61 // Objective-C
  62 @interface MyClass : NSObject {}
  63 @end
  64
  65 @implementation MyClass
  66 + (void)foo {
  67   MyClass *x = [[self alloc] init];
  68   // DynamicTypeInfo from a cast: from 'id' to 'MyClass *'
  69 }
  70 @end
  71
  72 void test() {
  73   MyClass *x = [MyClass alloc];
  74   // DynamicTypeInfo from a call to alloc:
  75   // from 'id' to 'MyClass *'
  76 }
  77 </pre></div></div></td></tr>
  78
  79
  80 <tr><td><div class="namedescr expandable"><span class="name">
  81 core.builtin.BuiltinFunctions</span><span class="lang">
  82 (C)</span><div class="descr">
  83 Evaluate compiler builtin functions (e.g., <code>alloca()</code>)</div></div></td>
  84 <td><div class="exampleContainer expandable">
  85 <div class="example"><pre>
  86 void test(int x) {
  87   int *p = (int *)__builtin_alloca(8);
  88     // evaluates to AllocaRegion
  89
  90   if(__builtin_expect(x > 10, 0)) // evaluates to 'x > 10'
  91     x = 0;
  92 }
  93 </pre></div></div></td></tr>
  94
  95
  96 <tr><td><div class="namedescr expandable"><span class="name">
  97 core.builtin.NoReturnFunctions</span><span class="lang">
  98 (C, ObjC)</span><div class="descr">
  99 Evaluate "panic" functions that are known to not return to the caller.</div></div></td>
 100 <td><div class="exampleContainer expandable">
 101 <div class="example"><pre>
 102 // C
 103 void test() {
 104   panic(); // generate sink
 105 }
 106 </pre></div><div class="separator"></div>
 107 <div class="example"><pre>
 108 // Objective-C
 109 @interface MyObj : NSObject {}
 110 - (void)foo;
 111 @end
 112
 113 @implementation MyObj
 114 - (void)foo {
 115   [[NSAssertionHandler currentHandler] handleFailureInMethod:_cmd
 116                                        object:self
 117                                        file:(@"somefile.m")
 118                                        lineNumber:1
 119                                        description:(@"some text")];
 120     // generate sink
 121 }
 122 @end
 123 </pre></div></div></td></tr>
 124
 125 </tbody></table>
 126
 127 <!-- =========================== OS X implicit =========================== -->
 128 <h3 id="osx_implicit_checkers">OS X Implicit Checkers</h3>
 129 <table class="checkers">
 130 <colgroup><col class="namedescr"><col class="example"></colgroup>
 131 <thead><tr><td>Name, Description</td><td>Example</td></tr></thead>
 132
 133 <tbody>
 134 <tr><td><div class="namedescr expandable"><span class="name">
 135 osx.cocoa.Loops</span><span class="lang">
 136 (ObjC)</span><div class="descr">
 137 Improved modeling of loops using Cocoa collection types.</div></div></td>
 138 <td><div class="exampleContainer expandable">
 139 <div class="example"><pre>
 140 void test() {
 141   id x;
 142   for (x in [NSArray testObject]) {
 143     // assume the value of 'x' is non-nil
 144   }
 145 }
 146 </pre></div></div></td></tr>
 147
 148
 149 <tr><td><div class="namedescr expandable"><span class="name">
 150 osx.cocoa.NonNilReturnValue</span><span class="lang">
 151 (ObjC)</span><div class="descr">
 152 Model the APIs that are guaranteed to return a non-nil value.</div></div></td>
 153 <td><div class="exampleContainer expandable">
 154 <div class="example"><pre>
 155 void test(NSArray *A) {
 156   id subscriptObj = A[1]; // assume the value is non-nil
 157 }
 158 </pre></div></div></td></tr>
 159
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