Cpp:s2095 FP when using scoped objects to close resource

[Tohnmeister (Tonni Tielens)]

S2095 reports resources that are not closed. It seems to ignore when the resources are closed using scoped objects to close the resource. E.g. a custom written scope_exit.

Example:

class scope_exit {
public:
    using ExitFunc = std::function<void()>;
    
    explicit scope_exit(ExitFunc exitFunc) :
        _exitFunc(std::move(exitFunc)) {
    }

    ~scope_exit() {
        if (_exitFunc) {
            _exitFunc();
        }
    }

    scope_exit(const scope_exit &) = delete;
    scope_exit& operator=(const scope_exit &) = delete;
    scope_exit(scope_exit &&other) noexcept {
        _exitFunc.swap(other._exitFunc);
        other._exitFunc = nullptr;
    } 
    scope_exit& operator=(scope_exit &&other) noexcept {
        if (this != &other) {
            _exitFunc();
            _exitFunc.swap(other._exitFunc);
            other._exitFunc = nullptr;
        }

        return *this;
    }
private:
    ExitFunc _exitFunc;

};

int main() {
    FILE* file = fopen("c:\\temp\\somefile.bin", "rb");
    scope_exit scoped([file] {
        fclose(file);
    });

    return 0;
}

I can see how this is a complex situation to analyze. Is there any way I can modify the scope_exit class to indicate to SonarLint that is in fact handling the resource?

[Abbas (Abbas Sabra)]

Hello @Tohnmeister,

Thanks for the detailed report.

I was able to reproduce the issue. It is related to the handling of `std::function. I created this ticket CPP-3703 that you can follow.

@Tohnmeister

Is there any way I can modify the scope_exit class to indicate to SonarLint that is in fact handling the resource?

I’m not sure that changing perfectly fine code to make SonarLint happy is the right approach. Instead, I would recommend:

• Using connected mode(if you are using SonarQube or SonarCloud). This way you can mark the issue as false-positive on the server and it won’t appear in your IDE.
• if you cannot use connected mode. I would suggest ignoring the issue and vote-up this under consideration feature: “Mute individual issues on-the-fly in your IDE”.

Thanks,