---

yaml
---
r: 341993
b: refs/heads/rxwei-patch-1
c: b89764a
h: refs/heads/master
i:
  341991: a386ffb

Author: drodriguez

[refs]

@@ -1015,7 +1015,7 @@ refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-08-18-a: b10b1fce14385faa6d44f6b933e95
 refs/heads/rdar-43033749-fix-batch-mode-no-diags-swift-5.0-branch: a14e64eaad30de89f0f5f0b2a782eed7ecdcb255
 refs/heads/revert-19006-error-bridging-integer-type: 8a9065a3696535305ea53fe9b71f91cbe6702019
 refs/heads/revert-19050-revert-19006-error-bridging-integer-type: ecf752d54b05dd0a20f510f0bfa54a3fec3bcaca
-refs/heads/rxwei-patch-1: b981afb29b26dc02966a75aaa09ed4fd9afca8c4
+refs/heads/rxwei-patch-1: b89764a05f014abdf98726e510c6f9a35f01b0f6
 refs/heads/shahmishal-patch-1: e58ec0f7488258d42bef51bc3e6d7b3dc74d7b2a
 refs/heads/typelist-existential: 4046359efd541fb5c72d69a92eefc0a784df8f5e
 refs/tags/swift-4.2-DEVELOPMENT-SNAPSHOT-2018-08-20-a: 4319ba09e4fb8650ee86061075c74a016b6baab9

branches/rxwei-patch-1/CHANGELOG.md

@@ -26,27 +26,24 @@ CHANGELOG
 Swift Next
 ----------
 
-* [SR-8974][]:
+* [SR-4206][]:
 
-  Duplicate tuple element labels are no longer allowed, because it leads
-  to incorrect behavior. For example:
+  A method override is no longer allowed to have a generic signature with 
+  requirements not imposed by the base method. For example:
 
   ```
-  let dupLabels: (foo: Int, foo: Int) = (foo: 1, foo: 2)
-
-  enum Foo { case bar(x: Int, x: Int) }
-  let f: Foo = .bar(x: 0, x: 1)
+  protocol P {}
+  
+  class Base {
+    func foo<T>(arg: T) {}
+  }
+  
+  class Derived: Base {
+    override func foo<T: P>(arg: T) {}
+  }
   ```
 
-  will now be diagnosed as an error. 
-
-  Note: You can still use duplicate labels when declaring functions and
-  subscripts, as long as the internal labels are different. For example:
-
-  ```
-  func foo(bar x: Int, bar y: Int) {}
-  subscript(a x: Int, a y: Int) -> Int {}
-  ```
+  will now be diagnosed as an error.
 
 * [SR-6118][]:
 
@@ -68,6 +65,28 @@ Swift Next
 Swift 5.1
 ---------
 
+* [SR-8974][]:
+
+  Duplicate tuple element labels are no longer allowed, because it leads
+  to incorrect behavior. For example:
+
+  ```
+  let dupLabels: (foo: Int, foo: Int) = (foo: 1, foo: 2)
+
+  enum Foo { case bar(x: Int, x: Int) }
+  let f: Foo = .bar(x: 0, x: 1)
+  ```
+
+  will now be diagnosed as an error. 
+
+  Note: You can still use duplicate argument labels when declaring functions and
+  subscripts, as long as the internal parameter names are different. For example:
+
+  ```
+  func foo(bar x: Int, bar y: Int) {}
+  subscript(a x: Int, a y: Int) -> Int {}
+  ```
+
 * [SE-0244][]:
 
   Functions can now hide their concrete return type by declaring what protocols
@@ -7708,6 +7727,7 @@ Swift 1.0
 [SR-2608]: <https://bugs.swift.org/browse/SR-2608>
 [SR-2672]: <https://bugs.swift.org/browse/SR-2672>
 [SR-2688]: <https://bugs.swift.org/browse/SR-2688>
+[SR-4206]: <https://bugs.swift.org/browse/SR-4206>
 [SR-4248]: <https://bugs.swift.org/browse/SR-4248>
 [SR-5581]: <https://bugs.swift.org/browse/SR-5581>
 [SR-5719]: <https://bugs.swift.org/browse/SR-5719>

branches/rxwei-patch-1/README.md

@@ -76,7 +76,7 @@ Please make sure you use Python 2.x. Python 3.x is not supported currently.
 
 #### macOS
 
-To build for macOS, you need [Xcode 11 beta](https://developer.apple.com/xcode/downloads/).
+To build for macOS, you need [Xcode 11 beta 4](https://developer.apple.com/xcode/downloads/).
 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.

branches/rxwei-patch-1/benchmark/Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:4.2
+// swift-tools-version:5.0
 
 import PackageDescription
 import Foundation
@@ -9,10 +9,15 @@ unsupportedTests.insert("ObjectiveCBridging")
 unsupportedTests.insert("ObjectiveCBridgingStubs")
 #endif
 
-// This is a stop gap hack so we can edit benchmarks in Xcode.
-let singleSourceLibraries: [String] = {
+//===---
+// Single Source Libraries
+//
+
+/// Return the source files in subDirectory that we will translate into
+/// libraries. Each source library will be compiled as its own module.
+func getSingleSourceLibraries(subDirectory: String) -> [String] {
   let f = FileManager.`default`
-  let dirURL = URL(fileURLWithPath: "single-source").absoluteURL
+  let dirURL = URL(fileURLWithPath: subDirectory)
   let fileURLs = try! f.contentsOfDirectory(at: dirURL,
                                             includingPropertiesForKeys: nil)
   return fileURLs.compactMap { (path: URL) -> String? in
@@ -25,27 +30,45 @@ let singleSourceLibraries: [String] = {
       return nil
     }
 
-    let s = String(c[0])
+    let name = String(c[0])
 
     // We do not support this test.
-    if unsupportedTests.contains(s) {
+    if unsupportedTests.contains(name) {
       return nil
     }
 
-    assert(s != "PrimsSplit")
-    return s
+    return name
   }
-}()
+}
+
+var singleSourceLibraryDirs: [String] = []
+singleSourceLibraryDirs.append("single-source")
+
+var singleSourceLibraries: [String] = singleSourceLibraryDirs.flatMap {
+  getSingleSourceLibraries(subDirectory: $0)
+}
 
-let multiSourceLibraries: [String] = {
+//===---
+// Multi Source Libraries
+//
+
+func getMultiSourceLibraries(subDirectory: String) -> [(String, String)] {
   let f = FileManager.`default`
-  let dirURL = URL(fileURLWithPath: "multi-source").absoluteURL
-  let fileURLs = try! f.contentsOfDirectory(at: dirURL,
-                                            includingPropertiesForKeys: nil)
-  return fileURLs.map { (path: URL) -> String in
-    return path.lastPathComponent
-  }
-}()
+  let dirURL = URL(string: subDirectory)!
+  let subDirs = try! f.contentsOfDirectory(at: dirURL, includingPropertiesForKeys: nil)
+  return subDirs.map { (subDirectory, $0.lastPathComponent) }
+}
+
+var multiSourceLibraryDirs: [String] = []
+multiSourceLibraryDirs.append("multi-source")
+
+var multiSourceLibraries: [(parentSubDir: String, name: String)] = multiSourceLibraryDirs.flatMap {
+  getMultiSourceLibraries(subDirectory: $0)
+}
+
+//===---
+// Products
+//
 
 var products: [Product] = []
 products.append(.library(name: "TestsUtils", type: .static, targets: ["TestsUtils"]))
@@ -54,9 +77,15 @@ products.append(.library(name: "DriverUtils", type: .static, targets: ["DriverUt
 products.append(.library(name: "ObjectiveCTests", type: .static, targets: ["ObjectiveCTests"]))
 #endif
 products.append(.executable(name: "SwiftBench", targets: ["SwiftBench"]))
-products.append(.library(name: "PrimsSplit", type: .static, targets: ["PrimsSplit"]))
+
 products += singleSourceLibraries.map { .library(name: $0, type: .static, targets: [$0]) }
-products += multiSourceLibraries.map { .library(name: $0, type: .static, targets: [$0]) }
+products += multiSourceLibraries.map {
+  return .library(name: $0.name, type: .static, targets: [$0.name])
+}
+
+//===---
+// Targets
+//
 
 var targets: [Target] = []
 targets.append(.target(name: "TestsUtils", path: "utils", sources: ["TestsUtils.swift"]))
@@ -73,7 +102,7 @@ swiftBenchDeps.append(.target(name: "ObjectiveCTests"))
 #endif
 swiftBenchDeps.append(.target(name: "DriverUtils"))
 swiftBenchDeps += singleSourceLibraries.map { .target(name: $0) }
-swiftBenchDeps += multiSourceLibraries.map { .target(name: $0) }
+swiftBenchDeps += multiSourceLibraries.map { .target(name: $0.name) }
 
 targets.append(
     .target(name: "SwiftBench",
@@ -92,20 +121,27 @@ var singleSourceDeps: [Target.Dependency] = [.target(name: "TestsUtils")]
 #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
 singleSourceDeps.append(.target(name: "ObjectiveCTests"))
 #endif
-targets += singleSourceLibraries.map { x in
-    return .target(name: x,
+
+targets += singleSourceLibraries.map { name in
+  return .target(name: name,
       dependencies: singleSourceDeps,
       path: "single-source",
-      sources: ["\(x).swift"])
+      sources: ["\(name).swift"])
 }
-targets += multiSourceLibraries.map { x in
-  return .target(name: x,
+
+targets += multiSourceLibraries.map { lib in
+  return .target(
+    name: lib.name,
     dependencies: [
       .target(name: "TestsUtils")
     ],
-    path: "multi-source/\(x)")
+    path: lib.parentSubDir)
 }
 
+//===---
+// Top Level Definition
+//
+
 let p = Package(
   name: "swiftbench",
   products: products,

branches/rxwei-patch-1/benchmark/README.md

@@ -1,10 +1,8 @@
-Swift Benchmark Suite
-=====================
+# Swift Benchmark Suite
 
 This directory contains the Swift Benchmark Suite.
 
-Running Swift Benchmarks
-------------------------
+## Running Swift Benchmarks
 
 To run Swift benchmarks, pass the `--benchmark` flag to `build-script`. The
 current benchmark results will be compared to the previous run's results if
@@ -16,8 +14,7 @@ impacting changes, and run the benchmarks again. Upon benchmark completion, the
 benchmark results for the development branch will be compared to the most
 recent benchmark results for `master`.
 
-Building with build-script
---------------------------
+## Building with build-script
 
 By default, Swift benchmarks for OS X are compiled during the Swift build
 process. To build Swift benchmarks for additional platforms, pass the following
@@ -33,8 +30,7 @@ drivers dynamically link Swift standard library dylibs from a path
 relative to their run-time location (../lib/swift) so the standard
 library should be distributed alongside them.
 
-Building Independently
-----------------------
+## Building Independently
 
 To build the Swift benchmarks using only an Xcode installation: install an
 Xcode version with Swift support, install cmake 2.8.12, and ensure Xcode is
@@ -110,8 +106,7 @@ installed libraries instead, enable
 This will reflect the performance of the Swift standard library
 installed on the device, not the one included in the Swift root.
 
-Using the Benchmark Driver
---------------------------
+## Using the Benchmark Driver
 
 ### Usage
 
@@ -154,17 +149,15 @@ You can use test numbers instead of test names like this:
 Test numbers are not stable in the long run, adding and removing tests from the
 benchmark suite will reorder them, but they are stable for a given build.
 
-Using the Harness Generator
----------------------------
+## Using the Harness Generator
 
 `scripts/generate_harness/generate_harness.py` runs `gyb` to automate generation
 of some benchmarks.
 
 ** FIXME ** `gyb` should be invoked automatically during the
    build so that manually invoking `generate_harness.py` is not required.
 
-Adding New Benchmarks
----------------------
+## Adding New Benchmarks
 
 The harness generator supports both single and multiple file tests.
 
@@ -244,8 +237,8 @@ public func run_YourTestName(N: Int) {
 The current set of tags are defined by the `BenchmarkCategory` enum in
 `TestsUtils.swift` .
 
-Testing the Benchmark Drivers
------------------------------
+## Testing the Benchmark Drivers
+
 When working on tests, after the initial build
 ````
 swift-source$ ./swift/utils/build-script -R -B

branches/rxwei-patch-1/cmake/modules/AddSwift.cmake

@@ -1512,10 +1512,9 @@ function(add_swift_host_library name)
 
   if(NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
     swift_install_in_component(TARGETS ${name}
-                               ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-                               LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-                               RUNTIME DESTINATION bin
-                               COMPONENT dev)
+      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT dev
+      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT dev
+      RUNTIME DESTINATION bin COMPONENT dev)
   endif()
 
   swift_is_installing_component(dev is_installing)
@@ -2139,10 +2138,15 @@ function(add_swift_target_library name)
 
       if(sdk STREQUAL WINDOWS AND CMAKE_SYSTEM_NAME STREQUAL Windows)
         swift_install_in_component(TARGETS ${name}-windows-${SWIFT_PRIMARY_VARIANT_ARCH}
-                                   RUNTIME DESTINATION "bin"
-                                   LIBRARY DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/${resource_dir}/${resource_dir_sdk_subdir}/${SWIFT_PRIMARY_VARIANT_ARCH}"
-                                   ARCHIVE DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/${resource_dir}/${resource_dir_sdk_subdir}/${SWIFT_PRIMARY_VARIANT_ARCH}"
-                                   COMPONENT "${SWIFTLIB_INSTALL_IN_COMPONENT}"
+                                   RUNTIME
+                                     DESTINATION "bin"
+                                     COMPONENT "${SWIFTLIB_INSTALL_IN_COMPONENT}"
+                                   LIBRARY
+                                     DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/${resource_dir}/${resource_dir_sdk_subdir}/${SWIFT_PRIMARY_VARIANT_ARCH}"
+                                     COMPONENT "${SWIFTLIB_INSTALL_IN_COMPONENT}"
+                                   ARCHIVE
+                                     DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/${resource_dir}/${resource_dir_sdk_subdir}/${SWIFT_PRIMARY_VARIANT_ARCH}"
+                                     COMPONENT "${SWIFTLIB_INSTALL_IN_COMPONENT}"
                                    PERMISSIONS ${file_permissions})
       else()
         swift_install_in_component(FILES "${UNIVERSAL_LIBRARY_NAME}"
@@ -2423,8 +2427,9 @@ function(add_swift_host_tool executable)
     ${ASHT_UNPARSED_ARGUMENTS})
 
   swift_install_in_component(TARGETS ${executable}
-                             RUNTIME DESTINATION bin
-                             COMPONENT ${ASHT_SWIFT_COMPONENT})
+                             RUNTIME
+                               DESTINATION bin
+                               COMPONENT ${ASHT_SWIFT_COMPONENT})
 
   swift_is_installing_component(${ASHT_SWIFT_COMPONENT} is_installing)
 

branches/rxwei-patch-1/docs/StandardLibraryProgrammersManual.md

@@ -50,6 +50,19 @@ TODO: Should this subsume or link to [AccessControlInStdlib.rst](https://github.
 
 Optionals can be unwrapped with `!`, which triggers a trap on nil. Alternatively, they can be `.unsafelyUnwrapped()`, which will check and trap in debug builds of user code. Internal to the standard library is `._unsafelyUnwrappedUnchecked()` which will only check and trap in debug builds of the standard library itself. These correspond directly with `_precondition`, `_debugPrecondition`, and `_sanityCheck`. See [that section](#precondition) for details.
 
+#### UnsafeBitCast and Casting References
+
+In general `unsafeBitCast` should be avoided because it's correctness relies on subtle assumptions that will never be enforced, and it indicates a bug in Swift's type system that should be fixed. It's less bad for non-pointer trivial types. Pointer casting should go through one of the memory binding API instead as a last resort.
+
+Reference casting is more interesting. References casting can include converting to an Optional reference and converting from a class constrained existential.
+
+The regular `as` operator should be able to convert between reference types with full dynamic checking.
+
+`unsafeDownCast` is just as capable, but is only dynamically checked in debug mode or if the cast requires runtime support.
+
+`_unsafeUncheckedDowncast` is the same but is only dynamically checked in the stdlib asserts build, or if the cast requires runtime support.
+
+`_unsafeReferenceCast` is only dynamically checked if the cast requires runtime support. Additionally, it does not impose any static `AnyObject` constraint on the incoming reference. This is useful in a generic context where the object-ness can be determined dynamically, as done in some bridged containers.
 
 ### Builtins