QOpenGLVertexArrayObject crash if QGLWidget not visible on close action

[alketi]

I have a Qt 5.2.1 program that uses QOpenGLVertexArrayObjects and creates more than one QGLWidget, each placed inside of a QStackedWidget. Thus, only one QGLWidget is visible at any one time.

The issue is -- if I close the program and the QGLWidget that uses a QOpenGLVertexArrayObject ISN'T currently visible, it crashes with the message:

Warning: QOpenGLVertexArrayObject::~QOpenGLVertexArrayObjec t() failed to make VAO's context current (opengl/qopenglvertexarrayobject.cpp:370, virtual QOpenGLVertexArrayObject::~QOpenGLVertexArrayObjec t())

Looking through the source code, the destructor of QOpenGLVertexArrayObject contains the following code:

/*!
    Destroys the QOpenGLVertexArrayObject and the underlying OpenGL resource.
*/
QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject()
{
    QOpenGLContext* ctx = QOpenGLContext::currentContext();
 
    Q_D(QOpenGLVertexArrayObject);
    QOpenGLContext *oldContext = 0;
    if (d->context && ctx && d->context != ctx) {
        oldContext = ctx;
        if (d->context->makeCurrent(oldContext->surface())) {
            ctx = d->context;
        } else {
            qWarning("QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject() failed to make VAO's context current");
            ctx = 0;
        }
    }
 
    if (ctx)
        destroy();
 
    if (oldContext) {
        if (!oldContext->makeCurrent(oldContext->surface()))
            qWarning("QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject() failed to restore current context");
    }
}

/*!
    Destroys the QOpenGLVertexArrayObject and the underlying OpenGL resource.
*/
QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject()
{
    QOpenGLContext* ctx = QOpenGLContext::currentContext();

    Q_D(QOpenGLVertexArrayObject);
    QOpenGLContext *oldContext = 0;
    if (d->context && ctx && d->context != ctx) {
        oldContext = ctx;
        if (d->context->makeCurrent(oldContext->surface())) {
            ctx = d->context;
        } else {
            qWarning("QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject() failed to make VAO's context current");
            ctx = 0;
        }
    }

    if (ctx)
        destroy();

    if (oldContext) {
        if (!oldContext->makeCurrent(oldContext->surface()))
            qWarning("QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject() failed to restore current context");
    }
}

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- Is it possible to use QOpenGLVertexArrayObjects in a QGLWidget that's not currently visible and close the program successfully?

- Is this a bug?

[ChrisW67]

The warning issued is not a crash. Where does it crash? Have you looked at the backtrace?