merge master

Author: scentini

CHANGELOG.md

@@ -4,29 +4,100 @@ CHANGELOG
 <details>
 <summary>Note: This is in reverse chronological order, so newer entries are added to the top.</summary>
 
-| Version                | Released   | Toolchain   |
-| :--------------------- | :--------- | :---------- |
-| [Swift 5.3](#swift-53) |            |             |
-| [Swift 5.2](#swift-52) | 2020-03-24 | Xcode 11.4  |
-| [Swift 5.1](#swift-51) | 2019-09-20 | Xcode 11.0  |
-| [Swift 5.0](#swift-50) | 2019-03-25 | Xcode 10.2  |
-| [Swift 4.2](#swift-42) | 2018-09-17 | Xcode 10.0  |
-| [Swift 4.1](#swift-41) | 2018-03-29 | Xcode 9.3   |
-| [Swift 4.0](#swift-40) | 2017-09-19 | Xcode 9.0   |
-| [Swift 3.1](#swift-31) | 2017-03-27 | Xcode 8.3   |
-| [Swift 3.0](#swift-30) | 2016-09-13 | Xcode 8.0   |
-| [Swift 2.2](#swift-22) | 2016-03-21 | Xcode 7.3   |
-| [Swift 2.1](#swift-21) | 2015-10-21 | Xcode 7.1   |
-| [Swift 2.0](#swift-20) | 2015-09-17 | Xcode 7.0   |
-| [Swift 1.2](#swift-12) | 2015-04-08 | Xcode 6.3   |
-| [Swift 1.1](#swift-11) | 2014-12-02 | Xcode 6.1.1 |
-| [Swift 1.0](#swift-10) | 2014-09-15 | Xcode 6.0   |
+| Version                   | Released   | Toolchain   |
+| :------------------------ | :--------- | :---------- |
+| [Swift Next](#swift-next) |
+| [Swift 5.3](#swift-53)    |            |             |
+| [Swift 5.2](#swift-52)    | 2020-03-24 | Xcode 11.4  |
+| [Swift 5.1](#swift-51)    | 2019-09-20 | Xcode 11.0  |
+| [Swift 5.0](#swift-50)    | 2019-03-25 | Xcode 10.2  |
+| [Swift 4.2](#swift-42)    | 2018-09-17 | Xcode 10.0  |
+| [Swift 4.1](#swift-41)    | 2018-03-29 | Xcode 9.3   |
+| [Swift 4.0](#swift-40)    | 2017-09-19 | Xcode 9.0   |
+| [Swift 3.1](#swift-31)    | 2017-03-27 | Xcode 8.3   |
+| [Swift 3.0](#swift-30)    | 2016-09-13 | Xcode 8.0   |
+| [Swift 2.2](#swift-22)    | 2016-03-21 | Xcode 7.3   |
+| [Swift 2.1](#swift-21)    | 2015-10-21 | Xcode 7.1   |
+| [Swift 2.0](#swift-20)    | 2015-09-17 | Xcode 7.0   |
+| [Swift 1.2](#swift-12)    | 2015-04-08 | Xcode 6.3   |
+| [Swift 1.1](#swift-11)    | 2014-12-02 | Xcode 6.1.1 |
+| [Swift 1.0](#swift-10)    | 2014-09-15 | Xcode 6.0   |
 
 </details>
 
+Swift Next
+----------
+
+* [SE-0287][]:
+
+  Implicit member expressions now support chains of member accesses, making the following valid:
+  
+  ```swift
+  let milky: UIColor = .white.withAlphaComponent(0.5)
+  let milky2: UIColor = .init(named: "white")!.withAlphaComponent(0.5)
+  let milkyChance: UIColor? = .init(named: "white")?.withAlphaComponent(0.5)
+  ```
+  
+  As is the case with the existing implicit member expression syntax, the resulting type of the chain must be the same as the (implicit) base, so it is not well-formed to write:
+  
+  ```swift
+  let cgMilky: CGColor = .white.withAlphaComponent(0.5).cgColor
+  ```
+  
+  (Unless, of course, appropriate `white` and `withAlphaComponent` members were defined on `CGColor`.)
+  
+  Members of a "chain" can be properties, method calls, subscript accesses, force unwraps, or optional chaining question marks. Furthermore, the type of each member along the chain is permitted to differ (again, as long as the base of the chain matches the resulting type) meaning the following successfully typechecks:
+  
+  ```swift
+  struct Foo {
+    static var foo = Foo()
+    static var bar = Bar()
+    
+    var anotherFoo: Foo { Foo() }
+    func getFoo() -> Foo { Foo() }
+    var optionalFoo: Foo? { Foo() }
+    subscript() -> Foo { Foo() }
+  }
+  
+  struct Bar {
+    var anotherFoo = Foo()
+  }
+
+  let _: Foo? = .bar.anotherFoo.getFoo().optionalFoo?.optionalFoo![]
+  ```
+
 Swift 5.3
 ---------
 
+* [SE-0279][] & [SE-0286][]:
+
+  Trailing closure syntax has been extended to allow additional labeled closures to follow the initial unlabeled closure:
+  
+  ```swift
+  // Single trailing closure argument
+  UIView.animate(withDuration: 0.3) {
+    self.view.alpha = 0
+  }
+  // Multiple trailing closure arguments
+  UIView.animate(withDuration: 0.3) {
+    self.view.alpha = 0
+  } completion: { _ in
+    self.view.removeFromSuperview()
+  }
+  ```
+  
+  Additionally, trailing closure arguments now match the appropriate parameter according to a forward-scan rule (as opposed to the previous backward-scan rule):
+  
+  ```swift
+  func takesClosures(first: () -> Void, second: (Int) -> Void = { _ in }) {}
+  
+  takesClosures {
+    print("First")
+  }
+  ```
+  
+  In the above example, the trailing closure argument matches parameter `first`, whereas pre-Swift-5.3 it would have matched `second`. In order to ease the transition to this new rule, cases in which the forward-scan and backward-scan match a single trailing closure to different parameters, the backward-scan result is preferred and a warning is emitted. This is expected to be upgraded to an error in the next major version of Swift.
+
 * [SR-7083][]:
 
   Property observers such as `willSet` and `didSet` are now supported on `lazy` properties:
@@ -8070,7 +8141,10 @@ Swift 1.0
 [SE-0268]: <https://github.com/apple/swift-evolution/blob/master/proposals/0268-didset-semantics.md>
 [SE-0269]: <https://github.com/apple/swift-evolution/blob/master/proposals/0269-implicit-self-explicit-capture.md>
 [SE-0276]: <https://github.com/apple/swift-evolution/blob/master/proposals/0276-multi-pattern-catch-clauses.md>
+[SE-0279]: <https://github.com/apple/swift-evolution/blob/master/proposals/0279-multiple-trailing-closures.md>
 [SE-0280]: <https://github.com/apple/swift-evolution/blob/master/proposals/0280-enum-cases-as-protocol-witnesses.md>
+[SE-0286]: <https://github.com/apple/swift-evolution/blob/master/proposals/0286-forward-scan-trailing-closures.md>
+[SE-0287]: <https://github.com/apple/swift-evolution/blob/master/proposals/0287-implicit-member-chains.md>
 
 [SR-75]: <https://bugs.swift.org/browse/SR-75>
 [SR-106]: <https://bugs.swift.org/browse/SR-106>

CMakeLists.txt

@@ -369,6 +369,10 @@ option(SWIFT_REPORT_STATISTICS
     "Create json files which contain internal compilation statistics"
     FALSE)
 
+option(SWIFT_DISABLE_OBJC_INTEROP
+    "Disable Objective-C interoperability even on platforms what would normally have it"
+    FALSE)
+
 #
 # User-configurable experimental options.  Do not use in production builds.
 #
@@ -386,10 +390,6 @@ option(SWIFT_RUNTIME_ENABLE_LEAK_CHECKER
   "Should the runtime be built with support for non-thread-safe leak detecting entrypoints"
   FALSE)
 
-option(SWIFT_STDLIB_USE_NONATOMIC_RC
-    "Build the standard libraries and overlays with nonatomic reference count operations enabled"
-    FALSE)
-
 option(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS
   "Enable runtime function counters and expose the API."
   FALSE)
@@ -629,6 +629,22 @@ if("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQU
   set(SWIFT_COMPILER_IS_MSVC_LIKE TRUE)
 endif()
 
+if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
+  # CMake's default for CMAKE_CXX_FLAGS_RELEASE is "-O3 -DNDEBUG". Let's avoid "-O3" for consistency
+  # between Release and RelWithDebInfo. Dropping -DNDEBUG from this setting is blocked by triggering
+  # a test failure of Swift-Unit :: Syntax/./SwiftSyntaxTests/TypeSyntaxTests.MetatypeTypeWithAPIs
+  # because unit tests don't currently explicitly set -DNDEBUG/-UNDEBUG.
+  set(CMAKE_CXX_FLAGS_RELEASE "-O2 -DNDEBUG")
+
+  _compute_lto_flag("${SWIFT_TOOLS_ENABLE_LTO}" _lto_flag_out)
+  if(_lto_flag_out)
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_RELEASE} -gline-tables-only")
+    set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -gline-tables-only")
+  endif()
+else()
+  
+endif()
+
 #
 # Configure SDKs.
 #
@@ -898,7 +914,6 @@ if(NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   endif()
 endif()
 
-find_package(Python2 COMPONENTS Interpreter REQUIRED)
 find_package(Python3 COMPONENTS Interpreter REQUIRED)
 
 #

README.md

@@ -104,6 +104,14 @@ The required version of Xcode changes frequently, and is often a beta release.
 Check this document or the host information on <https://ci.swift.org> for the
 current required version.
 
+Swift's build tooling is meant to support spaces in the paths passed to them,
+but using spaces sometimes tickles bugs in Swift's build scripts or the tools
+they rely on. For example, [SR-13441](https://bugs.swift.org/browse/SR-13441)
+is caused by a space in the Xcode path used on macOS. If you see Swift's build
+tooling misbehave due to a space in a path, please
+[report the bug on the Swift bug tracker](https://swift.org/contributing/#reporting-bugs)
+and then change the path to work around it.
+
 You will also need [CMake](https://cmake.org) and [Ninja](https://ninja-build.org),
 which can be installed via a package manager:
 

benchmark/CMakeLists.txt

@@ -91,6 +91,7 @@ set(SWIFT_BENCH_MODULES
     single-source/Fibonacci
     single-source/FindStringNaive
     single-source/FlattenList
+    single-source/FloatingPointConversion
     single-source/FloatingPointParsing
     single-source/FloatingPointPrinting
     single-source/Hanoi
@@ -136,6 +137,7 @@ set(SWIFT_BENCH_MODULES
     single-source/PrefixWhile
     single-source/Prims
     single-source/PrimsNonStrongRef
+    single-source/ProtocolConformance
     single-source/ProtocolDispatch
     single-source/ProtocolDispatch2
     single-source/Queue

benchmark/scripts/Template.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2020 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -19,4 +19,4 @@ public let {name} = [
 @inline(never)
 public func run_{name}(N: Int) {{
     // TODO
-}}
+}}