(edited)
koher
struct Foo { var count: Int = 0 var a: Int = 42 { didSet { print("Foo.a didSet: \(count)") count += 1 } } } struct Bar { var count: Int = 0 var foo: Foo = Foo() { didSet { print("Bar.foo didSet: \(count), \(foo.count)") count += 1 // foo.count += 100 self[keyPath: \Bar.foo].count += 100 } } } var bar = Bar() bar.foo.a = -1Version:
swift-4.1.1-RELEASEOutput:
Foo.a didSet: 0 Bar.foo didSet: 0, 1 Bar.foo didSet: 1, 101 Bar.foo didSet: 2, 201 Bar.foo didSet: 3, 301 Bar.foo didSet: 4, 401 Bar.foo didSet: 5, 501 Bar.foo didSet: 6, 601 Bar.foo didSet: 7, 701 Bar.foo didSet: 8, 801 Bar.foo didSet: 9, 901 Bar.foo didSet: 10, 1001 Bar.foo didSet: 11, 1101 Bar.foo didSet: 12, 1201 Bar.foo didSet: 13, 1301 Bar.foo didSet: 14, 1401 Bar.foo didSet: 15, 1501 Bar.foo didSet: 16, 1601 Bar.foo didSet: 17, 1701 Bar.foo didSet: 18, 1801 Bar.foo didSet: 19, 1901 Bar.foo didSet: 20, 2001 Bar.foo didSet: 21, 2101 Bar.foo didSet: 22, 2201 Bar.foo didSet: 23, 2301 Bar.foo didSet: 24, 2401 Bar.foo didSet: 25, 2501 Bar.foo didSet: 26, 2601 Bar.foo didSet: 27, 2701 Bar.foo didSet: 28, 2801 Bar.foo didSet: 29, 2901 Bar.foo didSet: 30, 3001 Bar.foo didSet: 31, 3101 Bar.foo didSet: 32, 3201 Bar.foo didSet: 33, 3301 Bar.foo didSet: 34, 3401 Bar.foo didSet: 35, 3501 Bar.foo didSet: 36, 3601 Bar.foo didSet: 37, 3701 Bar.foo didSet: 38, 3801 Bar.foo didSet: 39, 3901 ...Error:
/usr/bin/swift[0x3f24d64] /usr/bin/swift[0x3f250a6] /lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7fb6ec227390] /usr/lib/swift/linux/libswiftCore.so(swift_conformsToProtocol+0x3e)[0x7fb6e840373e] /usr/lib/swift/linux/libswiftCore.so(+0x39c05f)[0x7fb6e83f505f] /usr/lib/swift/linux/libswiftCore.so(+0x39b82d)[0x7fb6e83f482d] /usr/lib/swift/linux/libswiftCore.so(+0x2e518a)[0x7fb6e833e18a] Stack dump: 0. Program arguments: /usr/bin/swift -frontend -interpret /usercode/main.swift -disable-objc-interop -I /Libraries/All/.build/release -module-name main -lAll Segmentation fault (core dumped) 6/3/2018 3:51 PM