From 6f2fedde9ee20700eda6aebd1963a15087556ef2 Mon Sep 17 00:00:00 2001
From: "Timothy J. Wood" <tjw@omnigroup.com>
Date: Sun, 20 Mar 2016 13:33:32 -0700
Subject: [PATCH 1/2] [stdlib] SE-0061: Add Generic Result and Error Handling
 to autoreleasepool()

Added `rethrows` and generic return type to ObjectiveC.autoreleasepool.
Added tests of these new capabilities.

Fixes SR-1394 and SR-842
---
 stdlib/public/SDK/ObjectiveC/ObjectiveC.swift | 10 +++---
 test/Interpreter/SDK/autorelease.swift        | 36 +++++++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
index 8839665049d97..71d818b6b246b 100644
--- a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
+++ b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
@@ -181,7 +181,7 @@ public struct NSZone {
 typealias Zone = NSZone
 
 //===----------------------------------------------------------------------===//
-// FIXME: @autoreleasepool substitute
+// @autoreleasepool substitute
 //===----------------------------------------------------------------------===//
 
 @warn_unused_result
@@ -191,10 +191,12 @@ func __pushAutoreleasePool() -> OpaquePointer
 @_silgen_name("_swift_objc_autoreleasePoolPop")
 func __popAutoreleasePool(_ pool: OpaquePointer)
 
-public func autoreleasepool(_ code: @noescape () -> Void) {
+public func autoreleasepool<Result>(_ body: @noescape () throws -> Result) rethrows -> Result {
   let pool = __pushAutoreleasePool()
-  code()
-  __popAutoreleasePool(pool)
+  defer {
+    __popAutoreleasePool(pool)
+  }
+  return try body()
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/test/Interpreter/SDK/autorelease.swift b/test/Interpreter/SDK/autorelease.swift
index ef5436795c421..e3c8c0be39e5d 100644
--- a/test/Interpreter/SDK/autorelease.swift
+++ b/test/Interpreter/SDK/autorelease.swift
@@ -34,3 +34,39 @@ print("autorelease test end")
 // CHECK-NEXT: object died
 // CHECK-NEXT: after call to useTemp
 // CHECK-NEXT: autorelease test end
+
+// Using an @objc class to check that errors are retained across the pool
+// boundaries. A classic crash is an error created inside a pool and then
+// zombied before handling it outside the pool.
+@objc class Error: NSObject, ErrorProtocol {
+  let message:String
+  init(message:String) {
+    self.message = message
+  }
+}
+
+// Check that rethrow works.
+func requireString(string:String?) throws -> String {
+  guard let string = string else {
+    throw Error(message:"no string")
+  }
+  print("returning \"\(string)\"")
+  return string
+}
+do {
+  try autoreleasepool {
+    try requireString(string: "ok")
+    try requireString(string: nil)
+  }
+} catch let err as Error {
+  print("caught \"\(err.message)\"")
+}
+// CHECK-NEXT:      returning "ok"
+// CHECK-NEXT:      caught "no string"
+
+// Check that a return value can be passed back.
+let result = try autoreleasepool {
+  return "a string"
+}
+print("result = \"\(result)\"")
+// CHECK-NEXT:      result = "a string"

From b5e3938e7b4735224ac119cea308f1cf7e92077f Mon Sep 17 00:00:00 2001
From: "Timothy J. Wood" <tjw@omnigroup.com>
Date: Wed, 4 May 2016 08:37:00 -0700
Subject: [PATCH 2/2] Updated for code style review.

---
 stdlib/public/SDK/ObjectiveC/ObjectiveC.swift |  4 +++-
 test/Interpreter/SDK/autorelease.swift        | 10 +++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
index 71d818b6b246b..d547adef51a51 100644
--- a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
+++ b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
@@ -191,7 +191,9 @@ func __pushAutoreleasePool() -> OpaquePointer
 @_silgen_name("_swift_objc_autoreleasePoolPop")
 func __popAutoreleasePool(_ pool: OpaquePointer)
 
-public func autoreleasepool<Result>(_ body: @noescape () throws -> Result) rethrows -> Result {
+public func autoreleasepool<Result>(
+  _ body: @noescape () throws -> Result
+) rethrows -> Result {
   let pool = __pushAutoreleasePool()
   defer {
     __popAutoreleasePool(pool)
diff --git a/test/Interpreter/SDK/autorelease.swift b/test/Interpreter/SDK/autorelease.swift
index e3c8c0be39e5d..ee9a3b2583991 100644
--- a/test/Interpreter/SDK/autorelease.swift
+++ b/test/Interpreter/SDK/autorelease.swift
@@ -38,17 +38,17 @@ print("autorelease test end")
 // Using an @objc class to check that errors are retained across the pool
 // boundaries. A classic crash is an error created inside a pool and then
 // zombied before handling it outside the pool.
-@objc class Error: NSObject, ErrorProtocol {
-  let message:String
-  init(message:String) {
+@objc class Error : NSObject, ErrorProtocol {
+  let message: String
+  init(message: String) {
     self.message = message
   }
 }
 
 // Check that rethrow works.
-func requireString(string:String?) throws -> String {
+func requireString(string: String?) throws -> String {
   guard let string = string else {
-    throw Error(message:"no string")
+    throw Error(message: "no string")
   }
   print("returning \"\(string)\"")
   return string