Question up Front

Why is the simple inclusion of SegmentedBounds causing stack corruption? It is never used (yet), and I can continue through the program after the corruption warning without any apparent adverse effects.

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Details

I have an OpenCV 2.4.10 project in Visual Studio 2013, which has suddenly started causing a stack corruption error:

Run-Time Check Failure #2 - Stack around the variable 'was_processed' was corrupted!

Interestingly, this is part of the OpenCV framework, not my code. It fails inside of sources/modules/highgui/src/window_w32.cpp in the WindowProc() function.

I can continue through the program with no apparent adverse effects, though.

Here is their code:

static LRESULT CALLBACK WindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
    LRESULT ret;

    if( hg_on_preprocess )
    {
        int was_processed = 0;
        int rethg = hg_on_preprocess(hwnd, uMsg, wParam, lParam, &was_processed);
        if( was_processed )
            return rethg;
    }
    ret = HighGUIProc(hwnd, uMsg, wParam, lParam);

    if(hg_on_postprocess)
    {
        int was_processed = 0;
        int rethg = hg_on_postprocess(hwnd, uMsg, wParam, lParam, &was_processed);
        if( was_processed )
            return rethg;
    }

    return ret;
} // <================= Debugger says it stopped here

Here is my code:

class ImageVariants {
public:
    Mat getOriginal() const;
    ...

private:
    Point3i Bounds3D;
    SubjectFace Face;
    Mat Mask;
    Mat Original;
    Bounds SegmentedBounds; // PROBLEMS
    Bounds Subject;

    bool boundsSet = false;
};

What fails:

Here is the kicker, SegmentedBounds is only declared and not (yet) used anywhere. Commenting it out "fixes" this problem.

Also, if the variable is of type Bounds* there is no corruption. It looks like if the memory footprint of ImageVariants exceeds a certain size, then we get problems.

This also happened before, under the exact same circumstances when the STL vector<> was declared and not used in the same class. I just removed it though, since I didn't need it.

How it is triggered:

I used OpenCV's HighGUI tools to interact with the program. Whenever I access a function from the ImageVariants class, it appears to bork:

Scalar color(255.0, 0.0, 0.0);
Point end(x, y);

//Draw the rectangle the user is drawing
Mat img = w->Segmenter.Variants.getOriginal();

rectangle(img, w->MouseStart, end, color, 1, 8, 0);
w->draw(&img);

getOriginal() just returns Original from the ImageVariants class. It doesn't access, set, or use SegmentedBounds in any way.

What I know:

• I'm a very experienced C++ developer, so things like "you don't know what you are doing", just an uninitialized variable, loop out of bounds, did you copy and paste code? etc... need not apply. This code is very well written and understood.
• The Bounds type you see associated with the variable just really just a fancy struct. It is very thoroughly used in many ways throughout the program without any problems.
• The Bounds type has passed all of its rigorous unit and integration tests, so there isn't something fundamentally wrong with it.

After about two weeks of struggling, I found the answer. Apparently, some features of some OpenCV modules require you to call a function to initialize the module before using it:

initModule_<module name>();

I hadn't mentioned this in my question, but I was using the features2d module in this class. Specifically I was using the KeyPoints object from that library. So, in the constructor I added:

initModule_features2d();

All of my problems went away, no strangeness needed. I'm not sure why these functions are totally undocumented, as I can't find anywhere what they even do, but they work.

Credit: nikk from this post made me aware of these function and saved my bacon, big time.