[stdlib] Work around ~Escapable breaking Optional.init syntax

Author: lorentey

stdlib/public/core/Optional.swift

@@ -162,12 +162,29 @@ where Wrapped: ~Copyable & ~Escapable {
   }
 }
 
-extension Optional where Wrapped: ~Copyable & ~Escapable {
+extension Optional where Wrapped: ~Copyable {
   /// Creates an instance that stores the given value.
   @_transparent
   @_preInverseGenerics
-  @lifetime(some)
-  public init(_ some: consuming Wrapped) { self = .some(some) }
+  public init(_ value: consuming Wrapped) {
+    // FIXME: Merge this with the generalization below.
+    // This is the original initializer, preserved to avoid breaking source
+    // compatibility with clients that use the `Optional.init` syntax to create
+    // a function reference. The ~Escapable generalization is currently breaking
+    // that. (rdar://147533059)
+    self = .some(value)
+  }
+}
+
+extension Optional where Wrapped: ~Copyable & ~Escapable {
+  /// Creates an instance that stores the given value.
+  @_transparent
+  @_alwaysEmitIntoClient
+  @lifetime(value)
+  public init(_ value: consuming Wrapped) {
+    // FIXME: Merge this into the original entry above.
+    self = .some(value)
+  }
 }
 
 extension Optional {

test/api-digester/Outputs/stability-stdlib-source-base.swift.expected

@@ -216,7 +216,7 @@ Constructor ExpressibleByNilLiteral.init(nilLiteral:) has generic signature chan
 Constructor ManagedBufferPointer.init(bufferClass:minimumCapacity:makingHeaderWith:) has generic signature change from <Header, Element> to <Header, Element where Element : ~Copyable>
 Constructor ManagedBufferPointer.init(unsafeBufferObject:) has generic signature change from <Header, Element> to <Header, Element where Element : ~Copyable>
 Constructor OpaquePointer.init(_:) has generic signature change from <T> to <T where T : ~Copyable>
-Constructor Optional.init(_:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable, Wrapped : ~Escapable>
+Constructor Optional.init(_:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable>
 Constructor Optional.init(_:) has parameter 0 changing from Default to Owned
 Constructor Optional.init(nilLiteral:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable, Wrapped : ~Escapable>
 Constructor Result.init(catching:) has generic signature change from <Success, Failure where Failure == any Swift.Error> to <Success, Failure where Failure : Swift.Error, Success : ~Copyable>

test/api-digester/stability-stdlib-abi-without-asserts.test

@@ -477,8 +477,8 @@ Constructor OpaquePointer.init(_:) has generic signature change from <T> to <T w
 Constructor OpaquePointer.init(_:) has mangled name changing from 'Swift.OpaquePointer.init<A>(Swift.Optional<Swift.UnsafePointer<A>>) -> Swift.Optional<Swift.OpaquePointer>' to 'Swift.OpaquePointer.init<A where A: ~Swift.Copyable>(Swift.Optional<Swift.UnsafePointer<A>>) -> Swift.Optional<Swift.OpaquePointer>'
 Constructor OpaquePointer.init(_:) has mangled name changing from 'Swift.OpaquePointer.init<A>(Swift.UnsafePointer<A>) -> Swift.OpaquePointer' to 'Swift.OpaquePointer.init<A where A: ~Swift.Copyable>(Swift.UnsafePointer<A>) -> Swift.OpaquePointer'
 Constructor OpaquePointer.init(_:) is now with @_preInverseGenerics
-Constructor Optional.init(_:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable, Wrapped : ~Escapable>
-Constructor Optional.init(_:) has mangled name changing from 'Swift.Optional.init(A) -> Swift.Optional<A>' to '(extension in Swift):Swift.Optional< where A: ~Swift.Copyable, A: ~Swift.Escapable>.init(A) -> Swift.Optional<A>'
+Constructor Optional.init(_:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable>
+Constructor Optional.init(_:) has mangled name changing from 'Swift.Optional.init(A) -> Swift.Optional<A>' to '(extension in Swift):Swift.Optional< where A: ~Swift.Copyable>.init(A) -> Swift.Optional<A>'
 Constructor Optional.init(_:) has parameter 0 changing from Default to Owned
 Constructor Optional.init(_:) is now with @_preInverseGenerics
 Constructor Optional.init(nilLiteral:) has generic signature change from <Wrapped> to <Wrapped where Wrapped : ~Copyable, Wrapped : ~Escapable>

test/stdlib/OptionalGeneralizations.swift

@@ -1,7 +1,8 @@
-// RUN: %target-run-simple-swift(-enable-experimental-feature NonescapableTypes)
+// RUN: %target-run-simple-swift(-enable-experimental-feature NonescapableTypes -enable-experimental-feature LifetimeDependence)
 // REQUIRES: executable_test
 // REQUIRES: reflection
 // REQUIRES: swift_feature_NonescapableTypes
+// REQUIRES: swift_feature_LifetimeDependence
 
 import StdlibUnittest
 import Swift
@@ -65,3 +66,29 @@ suite.test("Escapability") {
   expectFalse(isEscapable(Optional<NonescapableNontrivialStruct>.self))
 }
 #endif
+
+func apply<T, U>(
+  _ input: T,
+  _ body: (T) -> U
+) -> U {
+  body(input)
+}
+
+func apply2<T: ~Copyable, U: ~Copyable>(
+  _ input: consuming T,
+  _ body: (consuming T) -> U
+) -> U {
+  body(input)
+}
+
+suite.test("Initializer references") {
+  do {
+    let r = apply(TrivialStruct(), Optional.init)
+    expectTrue(r != nil)
+  }
+
+  do {
+    let r = apply2(NoncopyableStruct(), Optional.init)
+    expectTrue(r != nil)
+  }
+}