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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 315
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  • Bug76
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  • Code Smell207

  • Quick Fix 19
Filtered: 10 rules found
cppcoreguidelines
    Impact
      Clean code attribute
        1. Function-like macros should not be used

           Code Smell
        2. Boolean operations should not have numeric operands, and vice versa

           Bug
        3. A cast shall not remove any const or volatile qualification from the type of a pointer or reference

           Code Smell
        4. Loop variables should be declared in the minimal possible scope

           Code Smell
        5. Relational and subtraction operators should not be used with pointers to different arrays

           Bug
        6. Arguments evaluation order should not be relied on

           Bug
        7. User-defined types should not be passed as variadic arguments

           Bug
        8. Local variables and member data should not be volatile

           Code Smell
        9. Types and variables should be declared in separate statements

           Code Smell
        10. Type specifiers should be listed in a standard order

           Code Smell

        Local variables and member data should not be volatile

        consistency - conventional
        maintainability
        Code Smell
        • cppcoreguidelines
        • c11
        • multi-threading
        • cert
        • since-c++11

        Why is this an issue?

        More Info

        The main intended use-case for volatile in C and C++ is to access data that can be modified by something external to the program, typically some hardware register. In contrast with some other languages with a volatile keyword, it does not provide any useful guarantees related to atomicity, memory ordering, or inter-thread synchronization. It is only really needed for the kind of low-level code found in kernels or embedded software, i.e. using memory-mapped I/O registers to manipulate hardware directly.

        According to the C standard:

        volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation.

        Local variables and data members are completely controlled by the C++ language. This means they can’t change their value without the compiler knowing about it. Therefore, it doesn’t make sense for them to be marked as volatile.

        If the intent is to share those variables between threads, race conditions can be avoided by using synchronization primitives (such as std::mutex) or atomic types (_Atomic in C11, std::atomic<T> in C++11).

        This rule raises an issue when a local variable or class data member is declared as volatile (at the top level of the type, pointers to volatile are not reported).

        Noncompliant code example

        volatile int counter; // Noncompliant
        User * volatile vpUser; // Noncompliant; pointer is volatile
        User volatile * pvUser;  // Compliant; User instance is volatile, not the pointer
        

        Compliant solution

        atomic_int counter;
        std::atomic<User*> vpUser;
        User volatile * pvUser;
        
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