Warns when a lambda inside a connect captures local variables by reference. This usually results in a crash since the lambda might get called after the captured variable went out of scope.
int a;
connect(obj, &MyObj::mySignal, [&a]{ ... });
Although it's dangerous to capture by reference in other situations too, this check only warns for connects, otherwise it would generate false-positives in legitimate situations where you only use the lambda before going out of scope.