TIL Swift 6.4 warns about weak captures in nested closures

TIL Swift 6.4 warns when an inner closure captures [weak self] while the outer closure implicitly captures self strongly: Why Swift is introducing a warning for weak captures within nested closures.

timer = Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { _ in
    service.load { [weak self] in self?.update($0) } // outer closure still holds self strongly
}

Fix: move [weak self] to the outer closure.

[weak self] buried in an inner closure always bothered me — I had to trace the whole capture chain to see whether it does what the author expected. Good to have the compiler do this now.