1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
// RUN: %target-run-simple-swift( -enable-experimental-feature Embedded -wmo -runtime-compatibility-version none) | %FileCheck %s
// RUN: %target-run-simple-swift(-O -enable-experimental-feature Embedded -wmo -runtime-compatibility-version none) | %FileCheck %s
// REQUIRES: swift_in_compiler
// REQUIRES: executable_test
// REQUIRES: optimized_stdlib
// REQUIRES: OS=macosx || OS=linux-gnu
@dynamicMemberLookup
public struct Box<T>: ~Copyable {
init() {
self.value = UnsafeMutablePointer<T>.allocate(capacity: 1)
}
subscript<U>(dynamicMember member: WritableKeyPath<T, U>) -> U {
@_transparent
get { return self.value.pointer(to: member)!.pointee }
@_transparent
set { self.value.pointer(to: member)!.pointee = newValue }
}
var value: UnsafeMutablePointer<T>
}
public struct Foo {
var a: Int
var b: Int
}
public func test_read(x: inout Box<Foo>) -> Int {
return x.b
}
public func test_write(x: inout Box<Foo>) {
x.b = 42
}
var box = Box<Foo>()
_ = test_read(x: &box)
test_write(x: &box)
print(box.b)
// CHECK: 42
|
