Why does the body of FeatureView get recomputed when the alert is shown/dismissed? There is no @State on that view.

App.swift

@main
struct PreviewApp: App {
    var body: some Scene {
        WindowGroup {
            NavigationView {
                AlertContainer { route in
                    FeatureView(route: route)
                }
            }
            let _ = print(type(of: self), "body")
        }
    }
    
}

struct FeatureView: View {
    let route: Binding<String?>
    
    var body: some View {
        Button("Tap") {
            route.wrappedValue = "route"
        }
        let _ = print(type(of: self), "body")
    }
}

struct AlertContainer<C: View>: View {
    @State var route: String?
    @ViewBuilder let content: (Binding<String?>) -> C
    
    var body: some View {
        let _ = print(type(of: self), "body")
        content($route)
            .alert(isPresented: $route.hasValue(), content: {
                Alert(title: Text("Open \(String(describing: route))"))
            })
    }
}


extension Binding {
    func hasValue<T>() -> Binding<Bool> where Value == Optional<T> {
        .init {
            self.wrappedValue != nil
        } set: { newValue in
            if newValue == false {
                self.wrappedValue = nil
            }
        }
    }
}

https://twitter.com/alexito4/status/1466453681197522945

I was not expecting FeatureView.body to be called when the alert changes since that view doesn't have any observable state.

Binding conforms to DynamicProperty so from SwiftUI tracking perspective its like State.