False Positive unreadVariable + RAII lock_guard

[Frank Hackemesser]

Hello,

the following minimal example code gives the warning:
"Variable 'lock' is assigned a value that is never used CppCheck(unreadVariable)" warning.
In my opinion this is a false positive, as this is a valid RAII usage of a mutex lock guard.

#include <mutex>

std::mutex mutex;

std::lock_guard<std::mutex> lock_raii()
{
    return std::lock_guard<std::mutex>(mutex);
}

void test()
{
    {
        auto lock = lock_raii(); // THIS LINE GIVES THE WARNING
        // some protected code
    }
}

What do you think?

Regards,
Frank

[Daniel Marjamäki]

Thanks for reporting this. yes of course it's a false positive. I have created ticket https://trac.cppcheck.net/ticket/10505