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<h1>Available Checkers</h1>
The analyzer performs checks that are categorized into families or "checkers". The
default set of checkers covers a variety of checks targeted at finding security
and API usage bugs, dead code, and other logic errors. See the
<a href = "#default_checkers">Default Checkers</a> list below. In addition to
these, the analyzer contains a number of <a href = "alpha_checks.html">
Experimental (Alpha) Checkers</a>.

<h3>Writeups with examples of some of the bugs that the analyzer finds</h3>
<ul>
<li><a href="http://www.mobileorchard.com/bug-finding-with-clang-5-resources-to-get-you-started/">Bug Finding With Clang: 5 Resources To Get You Started</a></li>
<li><a href="http://fruitstandsoftware.com/blog/index.php/2008/08/finding-memory-leaks-with-the-llvmclang-static-analyzer/#comment-2">Finding Memory Leaks With The LLVM/Clang Static Analyzer</a></li>
<li><a href="http://www.rogueamoeba.com/utm/2008/07/14/the-clang-static-analyzer/">Under the Microscope - The Clang Static Analyzer</a></li>
<li><a href="http://www.mikeash.com/?page=pyblog/friday-qa-2009-03-06-using-the-clang-static-analyzer.html">Mike Ash - Using the Clang Static Analyzer</a></li>
</ul>

<h2 id="default_checkers">Default Checkers</h2>
<ul>
<li><a href="#core_checkers">Core Checkers</a> model core language features and perform general-purpose checks such as division by zero, null pointer dereference, usage of uninitialized values, etc.</li>
<li><a href="#cplusplus_checkers">C++ Checkers</a> perform C++-specific checks</li>
<li><a href="#deadcode_checkers">Dead Code Checkers</a> check for unused code</li>
<li><a href="#nullability_checkers">Nullability Checkers</a> </li>
<li><a href="#optin_checkers">Optin Checkers</a> </li>
<li><a href="#osx_checkers">OS X Checkers</a> perform Objective-C-specific checks and check the use of Apple's SDKs (OS X and iOS)</li>
<li><a href="#security_checkers">Security Checkers</a> check for insecure API usage and perform checks based on the CERT Secure Coding Standards</li>
<li><a href="#unix_checkers">Unix Checkers</a> check the use of Unix and POSIX APIs</li>
</ul>

<!-- =========================== core =========================== -->
<h3 id="core_checkers">Core Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
core.CallAndMessage</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for logical errors for function calls and Objective-C message expressions
(e.g., uninitialized arguments, null function pointers).</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
// C
struct S {
  int x;
};

void f(struct S s);

void test() {
  struct S s;
  f(s); // warn: passed-by-value arg contain uninitialized data
}
</pre></div>
<div class="example"><pre>
// C
void test() {
  void (*foo)(void);
  foo(); // warn: function pointer is uninitialized
}
</pre></div>
<div class="example"><pre>
// C
void test() {
  void (*foo)(void);
  foo = 0;
  foo(); // warn: function pointer is null
}
</pre></div>
<div class="example"><pre>
// C++
class C {
public:
  void f();
};

void test() {
  C *pc;
  pc-&gt;f(); // warn: object pointer is uninitialized
}
</pre></div>
<div class="example"><pre>
// C++
class C {
public:
  void f();
};

void test() {
  C *pc = 0;
  pc-&gt;f(); // warn: object pointer is null
}
</pre></div>
<div class="example"><pre>
// Objective-C
@interface MyClass : NSObject
@property (readwrite,assign) id x;
- (long double)longDoubleM;
@end

void test() {
  MyClass *obj1;
  long double ld1 = [obj1 longDoubleM];
    // warn: receiver is uninitialized
}
</pre></div>
<div class="example"><pre>
// Objective-C
@interface MyClass : NSObject
@property (readwrite,assign) id x;
- (long double)longDoubleM;
@end

void test() {
  MyClass *obj1;
  id i = obj1.x; // warn: uninitialized object pointer
}
</pre></div>
<div class="example"><pre>
// Objective-C
@interface Subscriptable : NSObject
- (id)objectAtIndexedSubscript:(unsigned int)index;
@end

@interface MyClass : Subscriptable
@property (readwrite,assign) id x;
- (long double)longDoubleM;
@end

void test() {
  MyClass *obj1;
  id i = obj1[0]; // warn: uninitialized object pointer
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.DivideZero</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for division by zero.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test(int z) {
  if (z == 0)
    int x = 1 / z; // warn
}
</pre></div>
<div class="example"><pre>
void test() {
  int x = 1;
  int y = x % 0; // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.NonNullParamChecker</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for null pointers passed as arguments to a function whose arguments are
marked with the <code>nonnull</code> attribute.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
int f(int *p) __attribute__((nonnull));

void test(int *p) {
  if (!p)
    f(p); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.NullDereference</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for dereferences of null pointers.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
// C
void test(int *p) {
  if (p)
    return;

  int x = p[0]; // warn
}
</pre></div>
<div class="example"><pre>
// C
void test(int *p) {
  if (!p)
    *p = 0; // warn
}
</pre></div>
<div class="example"><pre>
// C++
class C {
public:
  int x;
};

void test() {
  C *pc = 0;
  int k = pc->x; // warn
}
</pre></div>
<div class="example"><pre>
// Objective-C
@interface MyClass {
@public
  int x;
}
@end

void test() {
  MyClass *obj = 0;
  obj-&gt;x = 1; // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.StackAddressEscape</span><span class="lang">
(C)</span><div class="descr">
Check that addresses of stack memory do not escape the function.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
char const *p;

void test() {
  char const str[] = "string";
  p = str; // warn
}
</pre></div>
<div class="example"><pre>
void* test() {
   return __builtin_alloca(12); // warn
}
</pre></div>
<div class="example"><pre>
void test() {
  static int *x;
  int y;
  x = &amp;y; // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.UndefinedBinaryOperatorResult</span><span class="lang">
(C)</span><div class="descr">
Check for undefined results of binary operators.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  int y = x + 1; // warn: left operand is garbage
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.VLASize</span><span class="lang">
(C)</span><div class="descr">
Check for declarations of VLA of undefined or zero size.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  int vla1[x]; // warn: garbage as size
}
</pre></div>
<div class="example"><pre>
void test() {
  int x = 0;
  int vla2[x]; // warn: zero size
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.uninitialized.ArraySubscript</span><span class="lang">
(C)</span><div class="descr">
Check for uninitialized values used as array subscripts.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int i, a[10];
  int x = a[i]; // warn: array subscript is undefined
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.uninitialized.Assign</span><span class="lang">
(C)</span><div class="descr">
Check for assigning uninitialized values.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  x |= 1; // warn: left expression is unitialized
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.uninitialized.Branch</span><span class="lang">
(C)</span><div class="descr">
Check for uninitialized values used as branch conditions.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  if (x) // warn
    return;
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.uninitialized.CapturedBlockVariable</span><span class="lang">
(C)</span><div class="descr">
Check for blocks that capture uninitialized values.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  ^{ int y = x; }(); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
core.uninitialized.UndefReturn</span><span class="lang">
(C)</span><div class="descr">
Check for uninitialized values being returned to the caller.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
int test() {
  int x;
  return x; // warn
}
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== C++ =========================== -->
<h3 id="cplusplus_checkers">C++ Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
cplusplus.NewDelete</span><span class="lang">
(C++)</span><div class="descr">
Check for double-free, use-after-free and offset problems involving C++ <code>
delete</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void f(int *p);

void testUseMiddleArgAfterDelete(int *p) {
  delete p;
  f(p); // warn: use after free
}
</pre></div>
<div class="example"><pre>
class SomeClass {
public:
  void f();
};

void test() {
  SomeClass *c = new SomeClass;
  delete c;
  c-&gt;f(); // warn: use after free
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = (int *)__builtin_alloca(sizeof(int));
  delete p; // warn: deleting memory allocated by alloca
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = new int;
  delete p;
  delete p; // warn: attempt to free released
}
</pre></div>
<div class="example"><pre>
void test() {
  int i;
  delete &amp;i; // warn: delete address of local
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = new int[1];
  delete[] (++p);
    // warn: argument to 'delete[]' is offset by 4 bytes
    // from the start of memory allocated by 'new[]'
}
</pre></div></div></td></tr>

<tr><td><div class="namedescr expandable"><span class="name">
cplusplus.NewDeleteLeaks</span><span class="lang">
(C++)</span><div class="descr">
Check for memory leaks. Traces memory managed by <code>new</code>/<code>
delete</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int *p = new int;
} // warn
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== dead code =========================== -->
<h3 id="deadcode_checkers">Dead Code Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
deadcode.DeadStores</span><span class="lang">
(C)</span><div class="descr">
Check for values stored to variables that are never read afterwards.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x;
  x = 1; // warn
}
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== nullability =========================== -->
<h3 id="nullability_checkers">Nullability Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
nullability.NullPassedToNonnull</span><span class="lang">
(ObjC)</span><div class="descr">
Warns when a null pointer is passed to a pointer which has a 
_Nonnull type.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
if (name != nil)
  return;
// Warning: nil passed to a callee that requires a non-null 1st parameter
NSString *greeting = [@"Hello " stringByAppendingString:name];
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
nullability.NullReturnedFromNonnull</span><span class="lang">
(ObjC)</span><div class="descr">
Warns when a null pointer is returned from a function that has 
_Nonnull return type.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
- (nonnull id)firstChild {
  id result = nil;
  if ([_children count] > 0)
    result = _children[0];

  // Warning: nil returned from a method that is expected 
  // to return a non-null value
  return result;
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
nullability.NullableDereferenced</span><span class="lang">
(ObjC)</span><div class="descr">
Warns when a nullable pointer is dereferenced.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
struct LinkedList {
  int data;
  struct LinkedList *next;
};

struct LinkedList * _Nullable getNext(struct LinkedList *l);

void updateNextData(struct LinkedList *list, int newData) {
  struct LinkedList *next = getNext(list);
  // Warning: Nullable pointer is dereferenced
  next->data = 7;
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
nullability.NullablePassedToNonnull</span><span class="lang">
(ObjC)</span><div class="descr">
Warns when a nullable pointer is passed to a pointer which has a _Nonnull type.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
typedef struct Dummy { int val; } Dummy;
Dummy *_Nullable returnsNullable();
void takesNonnull(Dummy *_Nonnull);

void test() {
  Dummy *p = returnsNullable();
  takesNonnull(p); // warn
}
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== optin =========================== -->
<h3 id="optin_checkers">Optin Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
optin.mpi.MPI-Checker</span><span class="lang">
(C)</span><div class="descr">
Checks MPI code</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  double buf = 0;
  MPI_Request sendReq1;
  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 
      0, MPI_COMM_WORLD, &sendReq1);
} // warn: request 'sendReq1' has no matching wait.
</pre></div><div class="separator"></div>
<div class="example"><pre>
void test() {
  double buf = 0;
  MPI_Request sendReq;
  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq);
  MPI_Irecv(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // warn
  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // warn
  MPI_Wait(&sendReq, MPI_STATUS_IGNORE);
}
</pre></div><div class="separator"></div>
<div class="example"><pre>
void missingNonBlocking() {
  int rank = 0;
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Request sendReq1[10][10][10];
  MPI_Wait(&sendReq1[1][7][9], MPI_STATUS_IGNORE); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
optin.osx.cocoa.localizability.EmptyLocalizationContextChecker</span><span class="lang">
(ObjC)</span><div class="descr">
Check that NSLocalizedString macros include a comment for context.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
- (void)test {
  NSString *string = NSLocalizedString(@"LocalizedString", nil); // warn
  NSString *string2 = NSLocalizedString(@"LocalizedString", @" "); // warn
  NSString *string3 = NSLocalizedStringWithDefaultValue(
    @"LocalizedString", nil, [[NSBundle alloc] init], nil,@""); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
optin.osx.cocoa.localizability.NonLocalizedStringChecker</span><span class="lang">
(ObjC)</span><div class="descr">
Warns about uses of non-localized NSStrings passed to UI methods 
expecting localized NSStrings</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
NSString *alarmText = 
  NSLocalizedString(@"Enabled", @"Indicates alarm is turned on");
if (!isEnabled) {
  alarmText = @"Disabled";
}
UILabel *alarmStateLabel = [[UILabel alloc] init];

// Warning: User-facing text should use localized string macro
[alarmStateLabel setText:alarmText];
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== OS X =========================== -->
<h3 id="osx_checkers">OS X Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
osx.API</span><span class="lang">
(C)</span><div class="descr">
Check for proper uses of various Apple APIs:<div class=functions>
dispatch_once</div></div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  dispatch_once_t pred = 0;
  dispatch_once(&amp;pred, ^(){}); // warn: dispatch_once uses local
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.NumberObjectConversion</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for erroneous conversions of objects representing numbers 
into numbers</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
NSNumber *photoCount = [albumDescriptor objectForKey:@"PhotoCount"];
// Warning: Comparing a pointer value of type 'NSNumber *' 
// to a scalar integer value
if (photoCount > 0) {
  [self displayPhotos];
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.SecKeychainAPI</span><span class="lang">
(C)</span><div class="descr">
Check for improper uses of the Security framework's Keychain APIs:<div class=functions>
SecKeychainItemCopyContent<br>
SecKeychainFindGenericPassword<br>
SecKeychainFindInternetPassword<br>
SecKeychainItemFreeContent<br>
SecKeychainItemCopyAttributesAndData<br>
SecKeychainItemFreeAttributesAndData</div></div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  unsigned int *ptr = 0;
  UInt32 length;

  SecKeychainItemFreeContent(ptr, &amp;length);
    // warn: trying to free data which has not been allocated
}
</pre></div>
<div class="example"><pre>
void test() {
  unsigned int *ptr = 0;
  UInt32 *length = 0;
  void *outData;

  OSStatus st =
    SecKeychainItemCopyContent(2, ptr, ptr, length, outData);
    // warn: data is not released
}
</pre></div>
<div class="example"><pre>
void test() {
  unsigned int *ptr = 0;
  UInt32 *length = 0;
  void *outData;

  OSStatus st =
    SecKeychainItemCopyContent(2, ptr, ptr, length, &amp;outData);

  SecKeychainItemFreeContent(ptr, outData);
    // warn: only call free if a non-NULL buffer was returned
}
</pre></div>
<div class="example"><pre>
void test() {
  unsigned int *ptr = 0;
  UInt32 *length = 0;
  void *outData;

  OSStatus st =
    SecKeychainItemCopyContent(2, ptr, ptr, length, &amp;outData);

  st = SecKeychainItemCopyContent(2, ptr, ptr, length, &amp;outData);
    // warn: release data before another call to the allocator

  if (st == noErr)
    SecKeychainItemFreeContent(ptr, outData);
}
</pre></div>
<div class="example"><pre>
void test() {
  SecKeychainItemRef itemRef = 0;
  SecKeychainAttributeInfo *info = 0;
  SecItemClass *itemClass = 0;
  SecKeychainAttributeList *attrList = 0;
  UInt32 *length = 0;
  void *outData = 0;

  OSStatus st =
    SecKeychainItemCopyAttributesAndData(itemRef, info,
                                         itemClass, &amp;attrList,
                                         length, &amp;outData);

  SecKeychainItemFreeContent(attrList, outData);
    // warn: deallocator doesn't match the allocator
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.AtSync</span><span class="lang">
(ObjC)</span><div class="descr">
Check for nil pointers used as mutexes for <code>@synchronized</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test(id x) {
  if (!x)
    @synchronized(x) {} // warn: nil value used as mutex
}
</pre></div>
<div class="example"><pre>
void test() {
  id y;
  @synchronized(y) {} // warn: uninitialized value used as mutex
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.ClassRelease</span><span class="lang">
(ObjC)</span><div class="descr">
Check for sending <code>retain</code>, <code>release</code>, or <code>
autorelease</code> directly to a class.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface MyClass : NSObject
@end

void test(void) {
  [MyClass release]; // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.Dealloc</span><span class="lang">
(ObjC)</span><div class="descr">
Warn about Objective-C classes that lack a correct implementation 
of <code>-dealloc</code>.
</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface MyObject : NSObject {
  id _myproperty;  
}
@end

@implementation MyObject // warn: lacks 'dealloc'
@end
</pre></div><div class="separator"></div>
<div class="example"><pre>
@interface MyObject : NSObject {}
@property(assign) id myproperty;
@end

@implementation MyObject // warn: does not send 'dealloc' to super
- (void)dealloc {
  self.myproperty = 0;
}
@end
</pre></div><div class="separator"></div>
<div class="example"><pre>
@interface MyObject : NSObject {
  id _myproperty;
}
@property(retain) id myproperty;
@end

@implementation MyObject
@synthesize myproperty = _myproperty;
  // warn: var was retained but wasn't released
- (void)dealloc {
  [super dealloc];
}
@end
</pre></div><div class="separator"></div>
<div class="example"><pre>
@interface MyObject : NSObject {
  id _myproperty;
}
@property(assign) id myproperty;
@end

@implementation MyObject
@synthesize myproperty = _myproperty;
  // warn: var wasn't retained but was released
- (void)dealloc {
  [_myproperty release];
  [super dealloc];
}
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.IncompatibleMethodTypes</span><span class="lang">
(ObjC)</span><div class="descr">
Check for an incompatible type signature when overriding an Objective-C method.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface MyClass1 : NSObject
- (int)foo;
@end

@implementation MyClass1
- (int)foo { return 1; }
@end

@interface MyClass2 : MyClass1
- (float)foo;
@end

@implementation MyClass2
- (float)foo { return 1.0; } // warn
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
alpha.osx.cocoa.MissingSuperCall</span><span class="lang">
(ObjC)</span><div class="descr">
Warn about Objective-C methods that lack a necessary call to super. (Note: The
compiler now has a warning for methods annotated with <code>objc_requires_super</code>
attribute. The checker exists to check methods in the Cocoa frameworks
that haven't yet adopted this attribute.)</div></div></td>
<td><div class="example"><pre>
@interface Test : UIViewController
@end
@implementation test
- (void)viewDidLoad {} // warn
@end
</pre></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.NSAutoreleasePool</span><span class="lang">
(ObjC)</span><div class="descr">
Warn for suboptimal uses of NSAutoreleasePool in Objective-C
GC mode (<code>-fobjc-gc</code> compiler option).</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  [pool release]; // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.NSError</span><span class="lang">
(ObjC)</span><div class="descr">
Check usage of <code>NSError**</code> parameters.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface A : NSObject
- (void)foo:(NSError **)error;
@end

@implementation A
- (void)foo:(NSError **)error {
  // warn: method accepting NSError** should have a non-void
  // return value
}
@end
</pre></div>
<div class="example"><pre>
@interface A : NSObject
- (BOOL)foo:(NSError **)error;
@end

@implementation A
- (BOOL)foo:(NSError **)error {
  *error = 0; // warn: potential null dereference
  return 0;
}
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.NilArg</span><span class="lang">
(ObjC)</span><div class="descr">
Check for prohibited nil arguments in specific Objective-C method calls:<div class=functions>
- caseInsensitiveCompare:<br>
- compare:<br>
- compare:options:<br>
- compare:options:range:<br>
- compare:options:range:locale:<br>
- componentsSeparatedByCharactersInSet:<br>
- initWithFormat:</div></div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
NSComparisonResult test(NSString *s) {
  NSString *aString = nil;
  return [s caseInsensitiveCompare:aString];
    // warn: argument to 'NSString' method
    // 'caseInsensitiveCompare:' cannot be nil
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.ObjCGenerics</span><span class="lang">
(ObjC)</span><div class="descr">
Check for type errors when using Objective-C generics</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
NSMutableArray<NSString *> *names = [NSMutableArray array];
NSMutableArray *birthDates = names;

// Warning: Conversion from value of type 'NSDate *' 
// to incompatible type 'NSString *'
[birthDates addObject: [NSDate date]];
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.RetainCount</span><span class="lang">
(ObjC)</span><div class="descr">
Check for leaks and violations of the Cocoa Memory Management rules.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  NSString *s = [[NSString alloc] init]; // warn
}
</pre></div>
<div class="example"><pre>
CFStringRef test(char *bytes) {
  return CFStringCreateWithCStringNoCopy(
           0, bytes, NSNEXTSTEPStringEncoding, 0); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.SelfInit</span><span class="lang">
(ObjC)</span><div class="descr">
Check that <code>self</code> is properly initialized inside an initializer
method.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface MyObj : NSObject {
  id x;
}
- (id)init;
@end

@implementation MyObj
- (id)init {
  [super init];
  x = 0; // warn: instance variable used while 'self' is not
         // initialized
  return 0;
}
@end
</pre></div>
<div class="example"><pre>
@interface MyObj : NSObject
- (id)init;
@end

@implementation MyObj
- (id)init {
  [super init];
  return self; // warn: returning uninitialized 'self'
}
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.SuperDealloc</span><span class="lang">
(ObjC)</span><div class="descr">
Warn about improper use of '[super dealloc]' in Objective-C</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface SuperDeallocThenReleaseIvarClass : NSObject {
  NSObject *_ivar;
}
@end

@implementation SuperDeallocThenReleaseIvarClass
- (void)dealloc {
  [super dealloc];
  [_ivar release]; // warn
}
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.UnusedIvars</span><span class="lang">
(ObjC)</span><div class="descr">
Warn about private ivars that are never used.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
@interface MyObj : NSObject {
@private
  id x; // warn
}
@end

@implementation MyObj
@end
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.cocoa.VariadicMethodTypes</span><span class="lang">
(ObjC)</span><div class="descr">
Check for passing non-Objective-C types to variadic collection initialization
methods that expect only Objective-C types.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  [NSSet setWithObjects:@"Foo", "Bar", nil];
    // warn: argument should be an ObjC pointer type, not 'char *'
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.coreFoundation.CFError</span><span class="lang">
(C)</span><div class="descr">
Check usage of <code>CFErrorRef*</code> parameters.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test(CFErrorRef *error) {
  // warn: function accepting CFErrorRef* should have a
  // non-void return
}
</pre></div>
<div class="example"><pre>
int foo(CFErrorRef *error) {
  *error = 0; // warn: potential null dereference
  return 0;
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.coreFoundation.CFNumber</span><span class="lang">
(C)</span><div class="descr">
Check for improper uses of <code>CFNumberCreate</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
CFNumberRef test(unsigned char x) {
  return CFNumberCreate(0, kCFNumberSInt16Type, &amp;x);
   // warn: 8 bit integer is used to initialize a 16 bit integer
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.coreFoundation.CFRetainRelease</span><span class="lang">
(C)</span><div class="descr">
Check for null arguments to <code>CFRetain</code>, <code>CFRelease</code>,
<code>CFMakeCollectable</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test(CFTypeRef p) {
  if (!p)
    CFRetain(p); // warn
}
</pre></div>
<div class="example"><pre>
void test(int x, CFTypeRef p) {
  if (p)
    return;

  CFRelease(p); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.coreFoundation.containers.OutOfBounds</span><span class="lang">
(C)</span><div class="descr">
Checks for index out-of-bounds when using <code>CFArray</code> API.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  CFArrayRef A = CFArrayCreate(0, 0, 0, &amp;kCFTypeArrayCallBacks);
  CFArrayGetValueAtIndex(A, 0); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
osx.coreFoundation.containers.PointerSizedValues</span><span class="lang">
(C)</span><div class="descr">
Warns if <code>CFArray</code>, <code>CFDictionary</code>, <code>CFSet</code> are
created with non-pointer-size values.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int x[] = { 1 };
  CFArrayRef A = CFArrayCreate(0, (const void **)x, 1,
                               &amp;kCFTypeArrayCallBacks); // warn
}
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== security =========================== -->
<h3 id="security_checkers">Security Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
security.FloatLoopCounter</span><span class="lang">
(C)</span><div class="descr">
Warn on using a floating point value as a loop counter (CERT: FLP30-C,
FLP30-CPP).</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  for (float x = 0.1f; x <= 1.0f; x += 0.1f) {} // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.UncheckedReturn</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of functions whose return values must be always checked:<div class=functions>
setuid<br>
setgid<br>
seteuid<br>
setegid<br>
setreuid<br>
setregid</div></div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  setuid(1); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.getpw</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of the <code>getpw</code> function.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  char buff[1024];
  getpw(2, buff); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.gets</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of the <code>gets</code> function.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  char buff[1024];
  gets(buff); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.mkstemp</span><span class="lang">
(C)</span><div class="descr">
Warn when <code>mktemp</code>, <code>mkstemp</code>, <code>mkstemps</code> or
<code>mkdtemp</code> is passed fewer than 6
X's in the format string.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  mkstemp("XX"); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.mktemp</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of the <code>mktemp</code> function.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  char *x = mktemp("/tmp/zxcv"); // warn: insecure, use mkstemp
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.rand</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of inferior random number generating functions (only if <code>arc4random</code>
function is available):<div class=functions>
drand48<br>
erand48<br>
jrand48<br>
lcong48<br>
lrand48<br>
mrand48<br>
nrand48<br>
random<br>
rand_r</div></div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  random(); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.strcpy</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of the <code>strcpy</code> and <code>strcat</code> functions.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  char x[4];
  char *y = "abcd";

  strcpy(x, y); // warn
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
security.insecureAPI.vfork</span><span class="lang">
(C)</span><div class="descr">
Warn on uses of the <code>vfork</code> function.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  vfork(); // warn
}
</pre></div></div></td></tr>

</tbody></table>

<!-- =========================== unix =========================== -->
<h3 id="unix_checkers">Unix Checkers</h3>
<table class="checkers">
<colgroup><col class="namedescr"><col class="example"></colgroup>
<thead><tr><td>Name, Description</td><td>Example</td></tr></thead>

<tbody>
<tr><td><div class="namedescr expandable"><span class="name">
unix.API</span><span class="lang">
(C)</span><div class="descr">
Check calls to various UNIX/POSIX functions:<div class=functions>
open<br>
pthread_once<br>
calloc<br>
malloc<br>
realloc<br>
alloca<br>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
// Currently the check is performed for apple targets only.
void test(const char *path) {
  int fd = open(path, O_CREAT);
    // warn: call to 'open' requires a third argument when the
    // 'O_CREAT' flag is set
}
</pre></div>
<div class="example"><pre>
void f();

void test() {
  pthread_once_t pred = {0x30B1BCBA, {0}};
  pthread_once(&amp;pred, f);
    // warn: call to 'pthread_once' uses the local variable
}
</pre></div>
<div class="example"><pre>
void test() {
  void *p = malloc(0); // warn: allocation size of 0 bytes
}
</pre></div>
<div class="example"><pre>
void test() {
  void *p = calloc(0, 42); // warn: allocation size of 0 bytes
}
</pre></div>
<div class="example"><pre>
void test() {
  void *p = malloc(1);
  p = realloc(p, 0); // warn: allocation size of 0 bytes
}
</pre></div>
<div class="example"><pre>
void test() {
  void *p = alloca(0); // warn: allocation size of 0 bytes
}
</pre></div>
<div class="example"><pre>
void test() {
  void *p = valloc(0); // warn: allocation size of 0 bytes
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.Malloc</span><span class="lang">
(C)</span><div class="descr">
Check for memory leaks, double free, and use-after-free and offset problems
involving <code>malloc</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  int *p = malloc(1);
  free(p);
  free(p); // warn: attempt to free released memory
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = malloc(sizeof(int));
  free(p);
  *p = 1; // warn: use after free
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = malloc(1);
  if (p)
    return; // warn: memory is never released
}
</pre></div>
<div class="example"><pre>
void test() {
  int a[] = { 1 };
  free(a); // warn: argument is not allocated by malloc
}
</pre></div>
<div class="example"><pre>
void test() {
  int *p = malloc(sizeof(char));
  p = p - 1;
  free(p); // warn: argument to free() is offset by -4 bytes
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.MallocSizeof</span><span class="lang">
(C)</span><div class="descr">
Check for dubious <code>malloc</code>, <code>calloc</code> or
<code>realloc</code> arguments involving <code>sizeof</code>.</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  long *p = malloc(sizeof(short));
    // warn: result is converted to 'long *', which is
    // incompatible with operand type 'short'
  free(p);
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.MismatchedDeallocator</span><span class="lang">
(C, C++, ObjC)</span><div class="descr">
Check for mismatched deallocators (e.g. passing a pointer allocating
with <code>new</code> to <code>free()</code>).</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
// C, C++
void test() {
  int *p = (int *)malloc(sizeof(int));
  delete p; // warn
}
</pre></div>
<div class="example"><pre>
// C, C++
void __attribute((ownership_returns(malloc))) *user_malloc(size_t);

void test() {
  int *p = (int *)user_malloc(sizeof(int));
  delete p; // warn
}
</pre></div>
<div class="example"><pre>
// C, C++
void test() {
  int *p = new int;
  free(p); // warn
}
</pre></div>
<div class="example"><pre>
// C, C++
void test() {
  int *p = new int[1];
  realloc(p, sizeof(long)); // warn
}
</pre></div>
<div class="example"><pre>
// C, C++
template &lt;typename T&gt;
struct SimpleSmartPointer {
  T *ptr;

  explicit SimpleSmartPointer(T *p = 0) : ptr(p) {}
  ~SimpleSmartPointer() {
    delete ptr; // warn
  }
};

void test() {
  SimpleSmartPointer&lt;int&gt; a((int *)malloc(4));
}
</pre></div>
<div class="example"><pre>
// C++
void test() {
  int *p = (int *)operator new(0);
  delete[] p; // warn
}
</pre></div>
<div class="example"><pre>
// Objective-C, C++
void test(NSUInteger dataLength) {
  int *p = new int;
  NSData *d = [NSData dataWithBytesNoCopy:p
               length:sizeof(int) freeWhenDone:1];
    // warn +dataWithBytesNoCopy:length:freeWhenDone: cannot take
    // ownership of memory allocated by 'new'
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.Vfork</span><span class="lang">
(C)</span><div class="descr">
Check for proper usage of vfork</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
int test(int x) {
  pid_t pid = vfork(); // warn
  if (pid != 0)
    return 0;

  switch (x) {
  case 0:
    pid = 1;
    execl("", "", 0);
    _exit(1);
    break;
  case 1:
    x = 0; // warn: this assignment is prohibited
    break;
  case 2:
    foo(); // warn: this function call is prohibited
    break;
  default:
    return 0; // warn: return is prohibited
  }

  while(1);
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.cstring.BadSizeArg</span><span class="lang">
(C)</span><div class="descr">
Check the size argument passed to <code>strncat</code> for common erroneous
patterns. Use <code>-Wno-strncat-size</code> compiler option to mute other
<code>strncat</code>-related compiler warnings.
</div></div></td>
<td><div class="exampleContainer expandable">
<div class="example"><pre>
void test() {
  char dest[3];
  strncat(dest, "***", sizeof(dest));
    // warn: potential buffer overflow
}
</pre></div></div></td></tr>


<tr><td><div class="namedescr expandable"><span class="name">
unix.cstring.NullArg</span><span class="lang">
(C)</span><div class="descr">
Check for null pointers being passed as arguments to C string functions:<div class=functions>
strlen<br>
strnlen<br>
strcpy<br>
strncpy<br>
strcat<br>
strncat<br>
strcmp<br>
strncmp<br>
strcasecmp<br>
strncasecmp</div></div></div></td>
<td><div class="example"><pre>
int test() {
  return strlen(0); // warn
}
</pre></div></td></tr>

</tbody></table>

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