Implement a pointee initialization method that doesn't use lambdas

Library/Hylo/Core/PointerToMutable.hylo

@@ -93,4 +93,19 @@ public extension PointerToMutable where Pointee: Movable {
     return base as* (remote sink Pointee)
   }
 
+  /// Initialize the value at the address represented by `self` to `value`.
+  ///
+  /// - Requires: the `MemoryLayout<Pointee>.size()` bytes starting at the address are uninitialized
+  ///   and suitably aligned for `Pointee`.
+  public fun unsafe_initialize_pointee(_ value: sink Pointee) {
+    initialize<Pointee>(&(base as* (remote set Pointee)), to: value)
+  }
+
+}
+
+/// Initializes `x` to `y`.
+///
+/// - Note: This function is a workaround for the lack of `set` bindings (see #925).
+fun initialize<T: Movable>(_ x: set T, to y: sink T) {
+  &x = y
 }

Tests/LibraryTests/TestCases/PointerToMutableTests.hylo

@@ -24,16 +24,25 @@ fun test_advance() {
   precondition(!(f == e))
 }
 
-fun test_pointee() {
+fun test_initialize_pointee_lambda() {
   let p = PointerToMutable<Int>.allocate(count: 1)
   p.unsafe_initialize_pointee(fun (_ i: set Int) -> Void { &i = 42 })
   let y = p.unsafe_pointee()
-  precondition(42 == y)
+  precondition(y == 42)
+  p.deallocate()
+}
+
+fun test_initialize_pointee_direct() {
+  let p = PointerToMutable<Int>.allocate(count: 1)
+  p.unsafe_initialize_pointee(42)
+  let y = p.unsafe_pointee()
+  precondition(y == 42)
   p.deallocate()
 }
 
 public fun main() {
   test_advance_by_bytes()
   test_advance()
-  test_pointee()
+  test_initialize_pointee_lambda()
+  test_initialize_pointee_direct()
 }