6-5-2 and 6-5-4 on while loop checking std::vector::empty()

[cgpzs]

Hi,

We have a static analyzer that is reporting warnings related to 6-5-2 and 6-5-4 in the following code:

Code:

    std::vector<std::int32_t> v{};
    // Fill vector
    // ...
  
    // Consume vector
    while (!v.empty())  // <<< 6-5-2, 6-5-4 violated here?
    {
        std::int32_t const value{v.back()};
        v.pop_back();
        std::cout << value << "\n";
    }

The warning is that the "loop counter v" is not compared against a relational operator (6-5-2) nor is it modified via ++ et al. (6-5-4).

The static analysis tool vendor claims this is not a false positive and indeed it's required by the MISRA rules.

Could you shed some light as to whether the code above is violating 6-5-2 and 6-5-4? Is "v" really a loop counter as per the MISRA definition? One could argue that the loop counter is the private member std::vector::__size, but is that really the scope of this rule?

This code pattern is very typical when implementing e.g. graph search, having a list of Nodes and inspecting them one by one until a condition is reached or the list of nodes is empty. The list of nodes can typically grow while inspecting each node, so iterator-based searches are not a good implementation alternative.