QObject::connect says "no such signal"

[munna]

try this

QObject::connect(
        &sB,  SIGNAL(valueChanged(int)),
        &app, SLOT(quit())
    );

QObject::connect(
        &sB,  SIGNAL(valueChanged(int)),
        &app, SLOT(quit())
    );

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In signal and slot you should only specify the variable type and not the variable name.