# List of potential checkers

This page contains a list of potential checkers to implement in the static analyzer. If you are interested in contributing to the analyzer's development, this is a good resource to help you get started. The specific names of the checkers are subject to review, and are provided here as suggestions.

### allocation/deallocation

Name, Description | Example | Progress
memory.LeakNeverReleased (C, C++) Memory may be never released, potential leak of memory |
    #include <stdlib.h>

    int f() {};

    void test() {
      int *p1 = (int*)malloc(sizeof(int)); // warn
      int *p2 = new int; // warn
      int x = f();
      if (x==1)
        return;
      delete p2;
    }
| PR15237
memory.MismatchedFree enhancement to unix.Malloc (C, C++) Mismatched deallocation function is used |
    #include <stdlib.h>

    void test() {
      int *p1 = new int;
      int *p2 = new int[1];

      free(p1); // warn
      free(p2); // warn
    }
| PR15238
memory.LeakPtrValChanged enhancement to unix.Malloc (C, C++) Potential memory leak: a pointer to newly allocated data loses its original value |
    #include <stdlib.h>

    void f(const int *);
    void g(int *);

    void test() {
      int *p1 = new int;
      p1++; // warn
      int *p2 = (int *)malloc(sizeof(int));
      p2 = p1; // warn
      int *p3 = new int;
      f(p3);
      p3++; // warn
      int *p4 = new int;
      f(p4);
      p4++; // ok
    }
| done at r174678 (C case)
memory.LeakEvalOrder (C, C++) Potential memory leak: argument evaluation order is undefined, g() may never be called |
    #include <stdlib.h>

    void f1(int, int);
    void f2(int*, int*);
    int g(int *) { throw 1; };
    int h();

    void test() {
      f1(g(new int), h()); // warn
      f1(g((int *)malloc(sizeof(int))), h()); // warn
      f2(new int, new int);
    }
memory.DstBufferTooSmall (C, C++) Destination buffer too small |
    #include <string.h>

    void test() {
      const char* s1 = "abc";
      char *s2 = new char;
      strcpy(s2, s1); // warn

      int* p1 = new int[3];
      int* p2 = new int;
      memcpy(p2, p1, 3); // warn
    }
memory.NegativeArraySize enhancement to experimental.security.MallocOverflow (C, C++) 'n' is used to specify the buffer size may be negative |
    #include <stdlib.h>

    void test() {
      int *p;
      int n1 = -1;
      p = new int[n1]; // warn
    }

### constructors/destructors

Name, Description | Example | Progress
ctordtor.ExptInsideDtorExplicit (C++) It is dangerous to let an exception leave a destructor. Using try..catch will solve the problem. |
    void f();

    class A {
      A() {}
      ~A() { throw 1; } // warn
    };
ctordtor.ExptInsideDtorImplicit (C++) Calls to functions inside a destructor that are known to throw exceptions is dangerous. Using try..catch will solve the problem. |
    void f() { throw 1; };

    class A {
      A() {}
      ~A() { f(); } // warn
    };
ctordtor.PlacementSelfCopy (C++11) For a placement copy or move, it is almost certainly an error if the constructed object is also the object being copied from. |
    class A {};

    void test(A *dst, A *src) {
      ::new (dst) A(*dst); // warn (should be 'src')
    }

### va_list

Name, Description | Example | Progress
valist.Uninitialized Calls to the `va_arg`, `va_copy`, or `va_end` macro must happen after calling `va_start` and before calling `va_end`. |
    #include <stdarg.h>

    void test(int x, ...) {
      va_list args;
      int y = va_arg(args, int); // warn
      va_start(args, x);
      va_end(args, x);
      int z = va_arg(args, int); // warn
    }
| PR16811
valist.Unterminated Every `va_start` must be matched by a `va_end`. A va_list can only be ended once. This should be folded into the generalized "ownership checker" described on the Open Projects page. |
    #include <stdarg.h>

    void test(int x, ...) {
      va_list args;
      va_start(args, x);
      int y = x + va_arg(args, int);
      // missing va_end
    }
| PR16812

### exceptions

Name, Description | Example | Progress
exceptions.ThrowSpecButNotThrow (C++) Function prototype has throw(T) specifier but the function do not throw |
    void f() throw(int) { // warn
    }
exceptions.NoThrowSpecButThrows (C++) An exception is throw from a function having the throw() specifier |
    void f() throw() {
      throw(1); // warn
    }
exceptions.ThrownTypeDiffersSpec (C++) The type of a thrown exception differs from those specified in the throw(T) specifier |
    struct S{};
    void f() throw(int) {
      S s;
      throw (s); // warn
    }

### smart pointers

Name, Description | Example | Progress
smartptr.SmartPtrInit (C++) C++03: auto_ptr should store a pointer to an object obtained via new as allocated memory will be cleaned using delete C++11: one should use unique_ptr<T[]> to keep a pointer to memory allocated by new[] C++11: to keep a pointer to memory allocated by new[] in a shared_ptr one should use a custom deleter that calls delete[] |
    #include <stdlib.h>
    #include <memory>

    void test() {
      std::auto_ptr<int> p1(new int); // Ok
      std::auto_ptr<int> p2(new int[3]); // warn
      std::auto_ptr<int>
             p3((int *)malloc(sizeof(int))); // warn
    }

### dead code

Name, Description | Example | Progress
deadcode.UnmodifiedVariable (C, C++) A variable is never modified but was not declared const and is not a reference. (opt-in checker) |
    extern int computeDelta();

    int foo(bool cond) {
      int i = 0;
      if (cond) {
        const int delta = computeDelta();
        // Forgot to modify 'i'.
      }
      return i;
    }
| PR16890

### undefined behavior

Name, Description | Example | Progress
undefbehavior.ExitInDtor (C++) Undefined behavior: std::exit is called to end the program during the destruction of an object with static storage duration |
    #include <cstdlib>

    class A {
    public:
      ~A() {
        std::exit(1); // warn
      }
    };

    A a;
undefbehavior.LocalStaticDestroyed (C++) Undefined behavior: function containing a definition of static local object is called during the destruction of an object with static storage duration so that flow of control passes through the definition of the previously destroyed static local object |
    void f();

    class A {
    public:
      ~A() {
        f(); // warn
      }
    };

    class B {};

    A a;

    void f() {
      static B b; // <-
    }
undefbehavior.UseAfterRelease enhancement to unix.Malloc (C, C++) Pointer to deleted object is referenced (The effect of using an invalid pointer value is undefined) |
    #include <stdlib.h>

    void test() {
      int *p = new int;
      delete p;
      int i = *p; // warn
    }
undefbehavior.ZeroAllocDereference enhancement to unix.Malloc (C, C++) The effect of dereferencing a pointer returned as a request for zero size is undefined |
    #include <stdlib.h>

    int *p = new int[0];
    int i = p[0]; // warn
undefbehavior.DeadReferenced (C++) Undefined behavior: the following usage of the pointer to the object whose lifetime has ended can result in undefined behavior |
    // C++03
    #include <new>

    class A {
    public:
      int i;
      void f() {};
    };

    class B : public A {
    };

    void test() {
      B *b = new B;
      new(b) A;
      b->i; // warn
      b->f(); // warn
      static_cast<A*>(b); // warn
      dynamic_cast<A*>(b); // warn
      delete b; // warn
    }

    // C++11
    #include <new>

    class A {
    public:
      int i;
      void f() {};
    };

    class B : public A {
    public:
      ~B() {};
    };

    void test() {
      A *a = new A;
      new(a) B;
      a->i; // warn
      a->f(); // warn
      B *b = new B;
      new(b) A;
      b->i; // warn
      b->f(); // warn
      static_cast<A*>(b); // warn
      dynamic_cast<A*>(b); // warn
      delete b; // warn
    }
undefbehavior.ObjLocChanges (C++) Undefined behavior: the program must ensure that an object occupies the same storage location when the implicit or explicit destructor call takes place |
    #include <new>

    class T { };
    struct B {
      ~B();
    };

    void test() {
      B *b1 = new B;
      B b2;
      new (b1) T;
      new (&b2) T;
      delete b1; // warn
    } // warn
undefbehavior.ExprEvalOrderUndef (C, C++03) Undefined behavior: a scalar object shall have its stored value modified at most once by the evaluation of an expression |
    void test () {
      int i = 0;
      int v[1] = {0};
      i = v[i++]; // warn
      i = ++i + 1; // warn
    }
undefbehavior.StaticInitReentered (C) Undefined behavior: static declaration is re-entered while the object is being initialized |
    int test(int i) {
      static int s = test(2*i); // warn
      return i+1;
    }
undefbehavior.ConstModified (C, C++) Undefined behavior: const object is being modified |
    #include <stdlib.h>

    class X {
    public :
      mutable int i;
      int j;
    };
    class Y {
    public :
      X x;
      Y();
    };

    void test() {
      const int *ciq =
        (int *)malloc(sizeof(int));
      int *iq = const_cast<int *>(ciq);
      *iq = 1; // warn

      const Y y;
      Y* p = const_cast<Y*>(&y);
      p->x.i = 1; // ok
      p->x.j = 1; // warn
    }
undefbehavior.DeadDestructed (C++) Undefined behavior: the destructor is invoked for an object whose lifetime has ended |
    class A {
    public:
      void f() {};
      A() {};
      ~A() {};
    };

    void test() {
      A a;
      a.~A();
    } // warn
undefbehavior.MethodCallBeforeBaseInit (C++) Undefined behavior: calls member function but base not yet initialized |
    class A {
    public :
      A(int );
    };
    class B : public A {
    public :
      int f();
      B() : A(f()) {} // warn
    };
undefbehavior.MemberOrBaseRefBeforeCtor (C++) C++ Undefined behavior: non-static member or base class of non-POD class type is referred before constructor begins execution C++11 Undefined behavior: non-static member or base class of a class with a non-trivial constructor is referred before constructor begins execution |
    // C++03
    struct POD {
      int i;
    };

    struct non_POD : public POD {
      int j;
      POD pod;
    };

    extern POD pod;
    extern non_POD non_pod;

    int *p1 = &non_pod.j; // warn
    int *p2 = &non_pod.pod.i; // warn
    int *p3 = &pod.i; // ok
    POD *p4 = &non_pod; // warn

    POD a;
    non_POD b;

    struct S {
      int *k;
      non_POD non_pod;
      S() : k(&non_pod.j) {} // warn
    };

    // C++11
    struct trivial {
      int i;
    };

    struct non_trivial: public trivial {
      non_trivial() {};
      int j;
      trivial pod;
    };

    extern trivial t;
    extern non_trivial nt;

    int *p1 = &nt.j; // warn
    int *p2 = &nt.i; // warn
    int *p3 = &t.i; // ok
    trivial *p4 = &nt;

    trivial t;
    non_trivial nt;

    struct S {
      int *k;
      non_trivial nt;
      S() : k(&nt.j) {} // warn
    };
undefbehavior.MemberRefAfterDtor (C++) C++03: Undefined behavior: non-static member of non-POD class type is referred after destructor ends execution C++11: Undefined behavior: non-static member of a class with a non-trivial destructor is referred after destructor ends execution |
    // C++03
    struct non_POD {
      virtual void f() {};
    };

    void test() {
      non_POD *non_pod = new non_POD();
      non_pod->~non_POD();
      non_pod->f(); // warn
    }

    // C++11
    struct S {
      ~S() {};
      void f() {};
    };

    void test() {
      S *s = new S();
      s->~S();
      s->f(); // warn
    }
undefbehavior.CtorForeignCall (C++) Undefined behavior: call to virtual function of an object under construction whose type is neither the constructors own class or one of its bases |
    class A {
    public:
      virtual void f() {};
    };

    class B {
    public:
      B(A* a) { a->f(); } // warn
    };

    class C : public A, B {
    public:
      C() : B((A*)this) {}
    };
undefbehavior.CtorForeignCast undefbehavior.CtorForeignTypeid (C++) Undefined behavior: the operand of typeid/dynamic_cast is an object under construction whose type is neither the constructors own class or one of its bases |
    #include <typeinfo>

    class A {
    public:
      virtual void f() {};
    };

    class B {
    public:
      B(A* a) {
        typeid(*a); // warn
        dynamic_cast<B*>(a); //warn
      }
    };

    class C : public A, B {
    public:
      C() : B((A*)this) {}
    };
undefbehavior.MemberRefInCatch undefbehavior.BaseRefInCatch (C++) Undefined behavior: referring to any non-static member or base class of an object in the handler for a function-try-block of a constructor or destructor for that object results in undefined behavior |
    class C {
      int i;
    public :
      C()
      try
      : i(1) {}
      catch (...)
      {
        i=2; // warn
      }
    };
undefbehavior.ReturnAtCatchEnd (C++) Undefined behavior: a function returns when control reaches the end of a handler. This results in undefined behavior in a value-returning function |
    int test() try {
    }
    catch(int) {
    } // warn
undefbehavior.AutoptrsOwnSameObj (C++03) Undefined behavior: if more than one auto_ptr owns the same object at the same time the behavior of the program is undefined. |
    #include <memory>

    void test() {
      int *data = new int;
      std::auto_ptr<int> p(data);
      std::auto_ptr<int> q(data); // warn
    }
undefbehavior.BasicStringBoundAccess (C++03) Undefined behavior: out-of-bound basic_string access |
    void test() {
      std::basic_string<char> s;
      char c = s[10]; // warn
    }
undefbehavior.BasicStringBoundModification (C++) Undefined behavior: out-of-bound basic_string modification |
    void test() {
      std::basic_string<char> s;
      s[10] = 0; // warn
    }
undefbehavior.EosDereference (C++) Undefined behavior: the result of operator*() on an end of stream is undefined |
    #include <vector>

    void test() {
      std::vector<int> v;
      int i = *v.end(); // warn
      *v.end() = 0; // warn
    }
undefbehavior.QsortNonPOD undefbehavior.QsortNonTrivial C++ C++03: Undefined behavior: the objects in the array passed to qsort are of non-POD type C++11: Undefined behavior: the objects in the array passed to qsort are of non-trivial type |
    // C++03
    #include <cstdlib>

    struct non_POD {
      int i;
      non_POD(int ii) : i(ii) {}
    };

    non_POD values[] = { non_POD(2), non_POD(1) };

    int compare(const void *a,
                const void *b) {
      return ( (*(non_POD*)a).i -
               (*(non_POD*)b).i );
    }

    void test() {
      qsort(values, 2, sizeof(non_POD),
            compare); // warn
    }

    // C++11
    #include <cstdlib>

    struct S {};

    struct trivial_non_POD : public S {
      int i;
    };

    struct non_trivial {
      int i;
      non_trivial() {}
    };

    trivial_non_POD tnp[2];
    non_trivial nt[2];

    int compare1(const void *a,
                 const void *b) {
      return ( (*(trivial_non_POD *)a).i -
               (*(trivial_non_POD *)b).i );
    }

    int compare2(const void *a,
                 const void *b) {
      return ( (*(non_trivial *)a).i -
               (*(non_trivial *)b).i );
    }

    void test() {
      qsort(tnp, 2, sizeof(trivial_non_POD),
            compare1); // ok
      qsort(nt, 2, sizeof(non_trivial),
            compare2); // warn
    }
undefbehavior.ThrowWhileCopy C++ Undefined behavior: copy constructor/assignment operator can throw an exception. The effects are undefined if an exception is thrown. |
    struct S {
      int i, j;
      S (const S &s) {
        i = s.i;
        throw 1; // warn
        j = s.j;
      };
      S &operator=(const S &s) {
        i = s.i;
        throw 1; // warn
        j = s.j;
      }
    };
undefbehavior.ValarrayArgBound (C++) Undefined behavior: the value of the second argument is greater than the number of values pointed to by the first argument |
    #include <valarray>

    struct S {
      int i;
      S(int ii) : i(ii) {};
    };

    void test(void) {
      S s[] = { S(1), S(2) };
      std::valarray<S> v(s,3); // warn
    }
undefbehavior.ValarrayLengthDiffer (C++) Undefined behavior: valarray operands are of different length |
    // C++03
    #include <valarray>

    void test(void) {
      std::valarray<int> a(0, 1), b(0, 2);
      std::valarray<bool> c(false, 1);
      a = b; // warn
      a *= b; // warn
      a = a * b; // warn
      c = a == b; // warn
      b.resize(1);
      a = b; // OK
    }

    // C++11
    #include <valarray>

    void test(void) {
      std::valarray<int> a(0, 1), b(0, 2);
      std::valarray<bool> c(false, 1);
      a = b; // ok
      a *= b; // ok
      a = a * b; // warn
      c = a == b; // warn
      b.resize(1);
      a = b; // OK
    }
undefbehavior.ValarrayZeroLength (C++) Undefined behavior: calling sum()/min()/max() method of an array having zero length, the behavior is undefined |
    #include <valarray>

    void test(void) {
      std::valarray<int> v(0, 0);
      v.sum(); // warn
      v.min(); // warn
      v.max(); // warn
    }
undefbehavior.ValarrayBadIndirection (C++) Undefined behavior: element N is specified more than once in the indirection |
    #include <valarray>

    void test() {
      size_t addr[] = {0, 1, 1}; // N is 1
      std::valarray<size_t>indirect(addr, 3);
      std::valarray<int> a(0, 5), b(1, 3);
      a[indirect] = b; //warn
      a[indirect] *= b; //warn
    }
undefbehavior.IosBaseDestroyedBeforeInit (C++) Undefined behavior: ios_base object is destroyed before initialization have taken place. basic_ios::init should be call to initialize ios_base members |
    #include <ios>

    using namespace std;
    template <class T, class Traits = std::char_traits<T>>
    class my_stream1 : public std::basic_ios<T, Traits> {
    };

    template <class T, class Traits = std::char_traits<T>>
    class my_stream2 : public std::basic_ios<T, Traits> {
      class my_streambuf : public std::basic_streambuf<T, Traits> {
      };
    public:
      my_stream2() {
        this->init(new my_streambuf);
      }
    };

    void test() {
      my_stream1<char> *p1 = new my_stream1<char>
      my_stream2<char> *p2 = new my_stream2<char>
      delete p1; // warn
      delete p2; // ok
    }
undefbehavior.IosBaseUsedBeforeInit (C++11) Undefined behavior: ios_base object is used before initialization have taken place. basic_ios::init should be call to initialize ios_base members |
    #include <ios>

    using namespace std;
    template <class T, class Traits = std::char_traits<T>>
    class my_stream1 : public std::basic_ios<T, Traits> {
    };

    template <class T, class Traits = std::char_traits<T>>
    class my_stream2 : public std::basic_ios<T, Traits> {
      class my_streambuf : public std::basic_streambuf<T, Traits> {
      };
    public:
      my_stream2() {
        this->init(new my_streambuf);
      }
    };

    void test() {
      my_stream1<char> *p1 = new my_stream1<char>
      my_stream2<char> *p2 = new my_stream2<char>
      p1->narrow('a', 'b'); // warn
      p2->narrow('a', 'b'); // ok
      delete p1; // warn
      delete p2; // ok
    }
undefbehavior.MinusOnePosType (C++) Undefined behavior: passing -1 to any streambuf/istream/ostream member that accepts a value of type traits::pos_type result in undefined behavior |
    #include <fstream>

    class my_streambuf : public std::streambuf {
      void f() {
        seekpos(-1); // warn
      }
    };

    void test() {
      std::filebuf fb;
      std::istream in(&fb);
      std::ostream out(&fb);
      std::filebuf::off_type pos(-1);
      in.seekg(pos); // warn
      out.seekp(-1); // warn
    }

### different

Name, Description | Example | Progress
different.ArgEvalOrderUndef (C) Errors because of the order of evaluation of function arguments is undefined |
    void f(int, int);

    void test() {
      int i = 0;
      int v[1] = {0};
      f(v[i], i++); // warn
    }
different.IdenticalExprBinOp (C) There are identical sub-expressions to the left and to the right of the operator |
    #define A 1
    #define B 1

    bool isNan(double d) {
      return d != d; // ok
    }

    int f();

    void test() {
      int i = 0;
      if (i != 0 && i != 0) {} // warn

      if(i == A || i == B) {} // ok

      if (++i != 0 && ++i != 0) {} // ok

      if (f() && f()) {} // ok
    }
different.FuncPtrInsteadOfCall (C) Possibly a function call should be used instead of a pointer to function |
    int f();

    void test() {
      if (f == 0) {} // warn
    }
different.IdenticalCondIfElseIf (C) The use of 'if (A) {...} else if (A) {...}' pattern was detected. There is a probability of logical error presence |
    void test() {
      int i = 7;
      if (i == 1) {}
      else if (i == 1) {} // warn
    }
SuccessiveAssign (C) Successive assign to a variable |
    void test() {
      int i=0;
      i=1;
      i=2; // warn
    }
different.NullDerefStmtOrder enhancement to core.NullDereference (C) Dereferencing of the null pointer might take place. Checking the pointer for null should be performed first |
    struct S {
      int x;
    };

    S* f();

    void test() {
      S *p1 = f();
      int x1 = p1->x; // warn
      if (p1) {};

      S *p2 = f();
      int x2 = p2->x; // ok
    }
different.NullDerefCondOrder enhancement to core.NullDereference (C) Dereferencing of the null pointer might take place. Checking the pointer for null should be performed first |
    struct S{bool b;};

    S* f();

    void test() {
      S *p = f();
      if (p->b && p) {}; // warn
    }
different.IdenticalStmtThenElse (C) The 'else' statement is equivalent to the 'then' statement |
    void test() {
      int i;
      if (i==1) {
        i++;
      }
      else { // warn
        i++;
      }
    }
different.MultipleAccessors (C++) multiple accessors met for 'class::field' |
    class A {
      int i;
      int j;
    public:
      int getI() { return i; }
      int getJ() { return i; } // warn
      void setI(int& ii) { i = ii; }
      void setJ(int& jj) { i = jj; } // warn
    };
different.AccessorsForPublic (C++) Accessors exist for 'class::field'. Should this field really be public? |
    class A {
    public:
      int i; // warn
      int getI() { return i; }
      void setI(int& ii) { i = ii; }
    };
different.LibFuncResultUnised (C, C++) Calling 'f' ignoring its return value is of no use (* create the list of known system/library/API functions falling into this category) |
    #include <vector>

    void test() {
      std::vector<int> v;
      v.empty(); // warn
    }
different.WrongVarForStmt (C, C++) Possibly wrong variable is used in the loop/cond-expression of the 'for' statement. Did you mean 'proper_variable_name'? |
    void test() {
      int i;
      int j;
      for (j=0; j<3; ++i); // warn
      for (int j=0; i<3; ++j); // warn
    }
different.FloatingCompare (C) Comparing floating point numbers may be not precise |
    #include <math.h>

    void test() {
      double b = sin(M_PI / 6.0);
      if (b == 0.5) // warn
        b = 0;
    }
different.BoolCompare maybe merge with experimental.core.BoolAssignment (C, C++) Comparing boolean to a value other then 0 or 1 |
    void test() {
      int i;
      if (0 < i < 3) {}; // warn
      bool b;
      if (b == 3) {}; // warn
    }
different.BitwiseOpBoolArg maybe join with experimental.core.BoolAssignment (C, C++) bool value is used at the left/right part of the & (|) operator. Did you mean && (||) ? |
    int f();

    void test() {
      bool b = true;
      if (b & f()) {} // warn
    }
different.LabelInsideSwitch (C) Possible misprint: label found inside the switch() statement. (* did you mean 'default'?) |
    void test() {
      int c = 7;
      switch(c){
      case 1:
        c += 1; break;
      defalt: // warn
        c -= 1; break;
      }
    }
different.IdenticalCondIfIf (C) The conditions of two subsequent 'if' statements are identical |
    void test() {
      int c = 7;
      if (c > 5) // <-
        c += 1;
      if (c > 5) // warn
        c -= 1;
    }
different.CondOpIdenticalReturn (C) The return expressions of the '?:' operator are identical |
    void test() {
      unsigned a;
      a = a > 5 ? a : a; // warn
    }
different.LogicalOpUselessArg (C) The second operand of the && operator has no impact on expression result |
    void test() {
      unsigned a;
      if (a<7 && a<10) {}; // warn
    }
different.SameResLogicalExpr (C) The expression always evaluates to true/false |
    void test() {
      int i=0;
      if (i!=0) {}; // warn
      if (i==0 && i==1) {}; // warn
      if (i<0 || i>=0) {}; // warn
    }
different.SameResUnsignedCmp (C) Comparison of unsigned expression 'op expr' is always true/false |
    void test() {
      unsigned u;
      if (u < -1) {}; // warn
      if (u >= 0) {}; // warn
    }
different.OpPrecedenceAssignCmp (C) Comparison operation has higher precedence then assignment. Bool value is assigned to variable of type 'type'. Parenthesis may bee required around an assignment |
    int f();

    void test() {
      bool b;
      int x, y;
      if((b = x != y)) {} // ok
      if((x = f() != y)) {} // warn
    }
different.OpPrecedenceIifShift (C) ?: has lower precedence then << |
    #include <iostream>

    void test() {
      int a;
      std::cout << a ? "a" : "b"; // warn
      a << a>7 ? 1 : 2; // warn
    }
different.ObjectUnused (C++) The object was created but is not being used The exception object was created but is not being used. Did you mean 'throw std::exception();'? |
    #include <exception>

    struct S {
      int x, y;
      S(int xx, int yy) : x(xx), y(yy) {
      }
      S(int xx) {
        S(xx, 0); // warn
      }
    };

    void test() {
      S(0, 0); // warn
      std::exception(); // warn
    }
different.StaticArrayPtrCompare (C) Pointer to static array is being compared to NULL. May the subscripting is missing |
    void test() {
      int a1[1];
      if (a1 == 0) {}; // warn

      int a2[1][1];
      if (a2[0]) {}; // warn
    }
different.ConversionToBool maybe join with experimental.core.BoolAssignment (C, C++) Odd implicit conversion from 'type' to 'bool' |
    bool test() {
      return 1.; // warn
      return ""; // warn
    }
different.ArrayBound enhancement to experimental.security.ArrayBound[v2] (C, C++) Out-of-bound dynamic array access |
    #include <stdlib.h>

    void test() {
      int *p2 = new int[1];
      if(p2[1]) {}; // warn
      int i = 1;
      if(p2[i]) {}; // warn
    }
different.StrcpyInputSize enhancement to experimental.unix.cstring.OutOfBounds (C) Buffer copy without checking size of input |
    void test(char* string) {
      char buf[24];
      strcpy(buf, string); // warn
    }
different.IntegerOverflow (C) Integer overflow |
    #include <limits.h>

    int f(int x) {
      return INT_MAX+1; // warn
    }

    void test() {
      int x = INT_MAX+1; // warn
      f(INT_MAX+1); // warn

      int y = INT_MAX/2+1; // warn
      x = y*2; // warn
    }
different.SignExtension (C) Unexpected sign extension might take place |
    void f(unsigned int i);
    int g();

    unsigned int test() {
      long long sll;
      unsigned long long ull = sll; // warn
      long sl;
      unsigned long ul = sl; // warn
      int si;
      unsigned int ui = si; // warn
      short ss;
      unsigned short us = ss; // warn
      signed char sc;
      unsigned char uc = sc; // warn
      f(si); // warn
      ui = g(); // warn
      return si; // warn
    }
different.NumericTruncation (C) Numeric truncation might take place |
    void f(int i);
    int g();

    int test() {
      unsigned long long ull;
      long long sll;
      unsigned long ul = ull; // warn
      long sl = sll; // warn
      unsigned int ui = ul; // warn
      int si = sl; // warn
      unsigned short us = ui; // warn
      short ss = si; // warn
      unsigned char uc = us; // warn
      signed char sc = uc; // warn
      f(sll); // warn
      ss = g(); // warn
      return sll; // warn
    }
different.MissingCopyCtorAssignOp (C, C++) The class has dynamically allocated data members but do not define a copy constructor/assignment operator |
    class C { // warn
      int *p; // <-
    public:
      C() { p = new int; }
      ~C() { delete p; }
    };

### WinAPI

Name, Description | Example | Progress
WinAPI.CreateProcess (C) After calling CreateProcess(), ensure that process and thread handles get closed (* for the given example: examine data flow from pi, pi.hProcess and pi.hThread) |
    #include <windows.h>

    void test() {
      STARTUPINFO si;
      PROCESS_INFORMATION pi;
      BOOL fSuccess;
      fSuccess = CreateProcess(
        NULL, TEXT("MyProgram.exe"), NULL, NULL,
        TRUE, 0, NULL, NULL, &si, &pi);
    } // warn
WinAPI.LoadLibrary (C) Calling LoadLibrary without a fully qualified path may allow to load a DLL from arbitrary location |
    #include <windows.h>

    void test() {
      HINSTANCE h = LoadLibrary("X.dll"); // warn
    }
WinAPI.WideCharToMultiByte (C) Buffer overrun while calling WideCharToMultiByte |
    #include <windows.h>

    void test()
    {
      wchar_t ws[] = L"abc";
      char s[3];
      int res1 = WideCharToMultiByte(
                   CP_UTF8, 0, ws, -1, s,
                   3, NULL, NULL); // warn
      int res2 = WideCharToMultiByte(
                   CP_UTF8, 0, ws, -1, s,
                   3, NULL, NULL); // ok
      if (res2 == sizeof(s))
        s[res2-1] = 0;
      else
       s[res2] = 0;
    }

### optimization

Name, Description | Example | Progress
optimization.PassConstObjByValue (C, C++) Optimization: It is more effective to pass const n-th parameter by reference to avoid unnecessary object copying |
    struct A {
      int a[20];
      int b;
    };

    bool FirstIsZero(const struct A a) { // warn
      return a.a[0] == 0;
    }
optimization.PostfixIncIter (C++) Optimization: It is more effective to use prefix ++ with iterator here |
    #include <vector>

    void test() {
      std::vector<int> v;
      std::vector<int>::const_iterator it;
      for(it = v.begin();
          it != v.end(); it++) {}; // warn
    }
optimization.MultipleCallsStrlen (C) Optimization: multiple calls to strlen for a given string in the given expression. It is more effective to hold strlen result in a temporary variable |
    #include <string.h>

    void test() {
      const char* s = "abc";
      if (strlen(s) > 0 &&
          strlen(s) < 7) {}; // warn
    }
optimization.EmptyCstrDetect (C) Optimization: it is more efficient to use "str[0] != '\0'" to identify an empty string |
    #include <string.h>

    void test() {
      const char* s = "abc";
      if (strlen(s) > 0) {}; // warn
    }
optimization.StrLengthCalculation (C, C++) Optimization: it is more efficient to use string::length() method to calculate string length |
    #include <string>
    #include <string.h>

    void test() {
      std::string s;
      if (strlen(s.c_str()) != 0) {}; // warn
    }
optimization.EmptyContainerDetect (C, C++) Optimization: It is more efficient to use container.empty() to identify an empty container |
    #include <list>

    void test() {
      std::list<int> l;
      if (l.size() != 0) {}; // warn
    }