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C++

C++ static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C++ code

  • All rules 674
  • Vulnerability13
  • Bug139
  • Security Hotspot19
  • Code Smell503

  • Quick Fix 91
Filtered: 22 rules found
unpredictable
    Impact
      Clean code attribute
        1. Globals should not depend on possibly not yet initialized variables

           Code Smell
        2. Coroutine should have co_return on each execution path or provide return_void

           Bug
        3. Thread local variables should not be used in coroutines

           Code Smell
        4. Arguments evaluation order should not be relied on

           Bug
        5. A single statement should not have more than one resource allocation

           Code Smell
        6. Functions that throw exceptions should not be used as hash functions

           Code Smell
        7. A call to "wait()" on a "std::condition_variable" should have a condition

           Bug
        8. Keywords shall not be used as macros identifiers

           Code Smell
        9. Incomplete types should not be deleted

           Code Smell
        10. Dereferenced null pointers should not be bound to references

           Code Smell
        11. Header guards should be followed by a matching "#define" macro

           Code Smell
        12. "memcmp" should only be called with pointers to trivially copyable types with no padding

           Bug
        13. Stack allocated memory and non-owned memory should not be freed

           Bug
        14. Destructors should not be called explicitly

           Code Smell
        15. An object shall not be accessed outside of its lifetime

           Bug
        16. Reads and writes on the same file stream shall be separated by a positioning operation

           Bug
        17. A pointer to an incomplete "class" type shall not be deleted

           Bug
        18. An object shall not be used while in a "potentially moved-from state"

           Code Smell
        19. A comparison of a "potentially virtual" pointer to member function shall only be with "nullptr"

           Bug
        20. Local variables shall not have static storage duration

           Code Smell
        21. The value of an object must not be read before it has been set

           Bug
        22. A line whose first token is "#" shall be a valid preprocessing directive

           Bug

        Globals should not depend on possibly not yet initialized variables

        intentionality - logical
        maintainability
        reliability
        Code Smell
        • unpredictable

        This rule raises an issue if the initializer of a global variable a, refers to another global variable b, when there is no guarantee that b is initialized before a.

        Why is this an issue?

        How can I fix it?

        More Info

        C++ allows global variables to have arbitrally complex initializers.

        Such variables are zero-initialized statically, and further initialization is performed at runtime, in the process referred to as dynamic initialization.

        The dynamic initialization of such variables is performed in the order of their definitions within a single source file. However, the order of initialization of variables defined in different source files is not specified. Therefore, when a global variable refers to a variable defined in a different source file, the behavior of the program is not guaranteed:

        extern int global1;
        // Defined in different source file as:
        // int global1 = 20;
        
        int const global2 = global1 + 10; // Noncompliant
        

        Depending on the order of initialization of global1 and global2, global2 may be set to:

        • 30 if global1 is initialized before global2
        • 10 if global2 is initialized before global1, as global1 will only be zero-initialized to 0.

        This rule raises an issue if the initializer of a global variable a, directly refers to another global variable b, when there is no guarantee that b is initialized before a.

        This is a subset of the issues related to initialization of global variables, commonly referred to as a static initialization order fiasco.

        What is the potential impact?

        The behavior of any program that is prone to static initialization order fiasco issues, is very fragile. The order of initialization may change at any time, for instance, when performing unrelated changes to the source code, or even differ between the builds of the same source. Such issues are very hard to reproduce and debug.

        Furthermore, the impact is not only limited to observing fluctuating values of global variables, as presented in the previous example.

        For class types, invoking any member functions of an object that is only zero-initialized and for which the constructor has not run, may cause undefined behavior and crash the program:

        extern std::string const string1;
        std::string const string2 = string1; // Noncompliant: undefined behavior
        

        Even if, for a particular implementation, zero-initialized objects are equivalent to default-initialized objects, the program may still encounter undefined behavior:

        extern std::vector<std::string> const list;
        // Defined in different source file as:
        // std::vector<std::string> const list{"entry1", "entry2"};
        
        std::string const firstElem = list[0]; // Noncompliant: undefined behavior
        

        Static class data members also use dynamic initialization

        Static data members of classes are dynamically initialized if their initializers are not constant expressions. Therefore, this rule will consider static data members of classes as if they were global variables.

        // Clazz.hpp
        extern int global;
        class Clazz {
          static int staticMem;
        };
        
        // Clazz.cpp
        #include "Clazz.hpp"
        
        int Clazz::staticMem = global + 10; // Noncompliant: "global" may not yet be fully initialized
        
        // Source.cpp
        #include "Clazz.hpp"
        
        int global = 10;
        int otherGlobal = Clazz::staticMem; // Noncompliant: "Clazz::staticMem" may not yet be fully initialized
        

        Initialization of instantiated variable is unordered

        If a global variable instantiated from a template requires a dynamic initialization (because its initialization is non-constant), the ordering of this initialization is unspecified. It may be performed before the initialization of a global variable declared before it. As a consequence, such variables should not refer to any dynamically initialized global variable in their initializers, or be referred to from the initializer of any global variable with dynamic initialization.

        An instantiated variable may be produced directly from the instantiation of a variable template (introduced in C++14):

        int global1 = runtimeFunc();
        
        template<typename T>
        T varTempl = global1; // Noncompliant: "global1" may be initialized later
        
        int global2 = varTempl<long>; // Noncompliant: "varTempl" may be initialized later
        

        Similarly, static data members of class template instantiation behave as instantiated global variables:

        int global1 = runtimeFunc();
        
        template<typename T>
        struct Clazz {
          static T staticMem;
        };
        
        template<typename T>
        T Clazz<T>::staticMem = global1; // Noncompliant: "global1" may be initialized later
        
        int global2 = Clazz<long>::staticMem; // Noncompliant: "Clazz<long>::staticMem" may be initialized later
        
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