Build compiler, other libraries, and tests for back-deployed concurrency.

When build-script is given `--back-deploy-concurrency`, also use that
to build other parts of Swift with the back-deployed versions:

* The compiler allows async and actors to be defined with the
back-deployed availability, e.g., the same as `-Xfrontend
-enable-experimental-back-deploy-concurrency`. (The latter will go
away soon)
* The standard library unit testing framework and distributed actors
library are build with the older OS versions.
* The tests use the older OS versions, with some adjustments to make
them agnostic to the back-deployment setting.

Author: DougGregor

stdlib/private/StdlibUnittest/CMakeLists.txt

@@ -20,6 +20,12 @@ if (SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED)
   list(APPEND swift_stdlib_unittest_link_libraries "swift_Distributed")
 endif()
 
+if (SWIFT_ALLOW_BACK_DEPLOY_CONCURRENCY)
+  set(swift_concurrency_availability "macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0")
+else()
+  set(swift_concurrency_availability "macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0")
+endif()
+
 add_swift_target_library(swiftStdlibUnittest ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
   # This file should be listed the first.  Module name is inferred from the
   # filename.
@@ -55,7 +61,7 @@ add_swift_target_library(swiftStdlibUnittest ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES}
   SWIFT_MODULE_DEPENDS_WINDOWS CRT WinSDK
   SWIFT_COMPILE_FLAGS ${swift_stdlib_unittest_compile_flags} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
     -Xfrontend -define-availability
-    -Xfrontend \"SwiftStdlib 5.5:macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0\"
+    -Xfrontend "SwiftStdlib 5.5:${swift_concurrency_availability}"
   INSTALL_IN_COMPONENT stdlib-experimental
   DARWIN_INSTALL_NAME_DIR "${SWIFT_DARWIN_STDLIB_PRIVATE_INSTALL_NAME_DIR}"
   LINK_LIBRARIES ${swift_stdlib_unittest_link_libraries})

stdlib/public/BackDeployConcurrency/CMakeLists.txt

@@ -38,7 +38,6 @@ endforeach()
 
 # Build the concurrency library for back deployment.
 add_compile_definitions(SWIFT_CONCURRENCY_BACK_DEPLOYMENT)
-set(swift_concurrency_swift_flags -Xfrontend -enable-experimental-back-deploy-concurrency)
 set(swift_concurrency_install_component back-deployment)
 set(swift_concurrency_options BACK_DEPLOYMENT_LIBRARY 5.5)
 

stdlib/public/Concurrency/CMakeLists.txt

@@ -99,7 +99,6 @@ add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
     -Dswift_Concurrency_EXPORTS
   SWIFT_COMPILE_FLAGS
     ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
-    ${swift_concurrency_swift_flags}
     -parse-stdlib
     -Xfrontend -enable-experimental-concurrency
     -Xfrontend -define-availability

stdlib/public/Distributed/CMakeLists.txt

@@ -13,6 +13,13 @@
 set(swift_distributed_link_libraries
   swiftCore)
 
+
+if (SWIFT_ALLOW_BACK_DEPLOY_CONCURRENCY)
+  set(swift_concurrency_availability "macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0")
+else()
+  set(swift_concurrency_availability "macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0")
+endif()
+
 add_swift_target_library(swift_Distributed ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
   AssertDistributed.swift
   ActorTransport.swift
@@ -34,7 +41,7 @@ add_swift_target_library(swift_Distributed ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
     -parse-stdlib
     -Xfrontend -enable-experimental-distributed
     -Xfrontend -define-availability
-    -Xfrontend \"SwiftStdlib 5.5:macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0\"
+    -Xfrontend "SwiftStdlib 5.5:${swift_concurrency_availability}"
   LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
 
   SWIFT_MODULE_DEPENDS _Concurrency

test/CMakeLists.txt

@@ -181,6 +181,7 @@ normalize_boolean_spelling(SWIFT_BUILD_SYNTAXPARSERLIB)
 normalize_boolean_spelling(SWIFT_ENABLE_SOURCEKIT_TESTS)
 normalize_boolean_spelling(SWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING)
 normalize_boolean_spelling(SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY)
+normalize_boolean_spelling(SWIFT_ALLOW_BACK_DEPLOY_CONCURRENCY)
 normalize_boolean_spelling(SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED)
 is_build_type_optimized("${SWIFT_STDLIB_BUILD_TYPE}" SWIFT_OPTIMIZED)
 
@@ -358,6 +359,10 @@ foreach(SDK ${SWIFT_SDKS})
           list(APPEND LIT_ARGS "--param" "concurrency")
         endif()
 
+        if(SWIFT_ALLOW_BACK_DEPLOY_CONCURRENCY)
+          list(APPEND LIT_ARGS "--param" "back_deploy_concurrency")
+        endif()
+
         if(SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED)
           list(APPEND LIT_ARGS "--param" "distributed")
         endif()

test/Concurrency/concurrency_availability.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -parse-stdlib -target x86_64-apple-macosx10.15 -typecheck -verify %s
+// RUN: %target-swift-frontend -parse-stdlib -target x86_64-apple-macosx10.14 -typecheck -verify %s
 // RUN: %target-swift-frontend -parse-stdlib -target x86_64-apple-macosx12 -typecheck %s
 // REQUIRES: OS=macosx
 

test/IRGen/async/weak_availability.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -enable-implicit-dynamic -target %target-cpu-apple-macosx11 -Onone -emit-ir %s | %FileCheck --check-prefix=MAYBE-AVAILABLE %s
+// RUN: %target-swift-frontend -enable-implicit-dynamic -target %target-cpu-apple-macosx10.14 -Onone -emit-ir %s | %FileCheck --check-prefix=MAYBE-AVAILABLE %s
 // REQUIRES: OS=macosx && CPU=x86_64
 
 @available(macOS 12.0, *)

test/ModuleInterface/actor_isolation.swift

@@ -11,70 +11,84 @@
 // REQUIRES: concurrency
 
 // CHECK: public actor SomeActor
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public actor SomeActor {
   nonisolated func maine() { }
 }
 
 // CHECK: @globalActor public struct SomeGlobalActor
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 @globalActor
 public struct SomeGlobalActor {
   public static let shared = SomeActor()
 }
 
 // CHECK: @{{(Test.)?}}SomeGlobalActor public protocol P1
 // CHECK-NEXT: @{{(Test.)?}}SomeGlobalActor func method()
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 @SomeGlobalActor
 public protocol P1 {
   func method()
 }
 
 // CHECK: class C1
 // CHECK-NEXT: @{{(Test.)?}}SomeGlobalActor public func method()
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C1: P1 {
   public func method() { }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 @SomeGlobalActor
 public class C2 { }
 
 // CHECK: @{{(Test.)?}}SomeGlobalActor public class C2
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C3: C2 { }
 
 // CHECK: public class C4 : Swift.UnsafeSendable
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C4: UnsafeSendable { }
 
 // CHECK: public class C5 : @unchecked Swift.Sendable
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C5: @unchecked Sendable { }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C6 { }
 
 // CHECK: extension {{(Test.)?}}C6 : @unchecked Swift.Sendable
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 extension C6: @unchecked Sendable { }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public class C7 { }
 
 // CHECK: extension {{(Test.)?}}C7 : Swift.UnsafeSendable
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 extension C7: UnsafeSendable { }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
+@available(SwiftStdlib 5.5, *)
 public protocol P2 {
   @SomeGlobalActor func method()
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+
 // CHECK: class {{(Test.)?}}C8 : {{(Test.)?}}P2 {
+@available(SwiftStdlib 5.5, *)
 public class C8 : P2 {
   // CHECK: @{{(Test.)?}}SomeGlobalActor public func method()
   public func method() {}

test/ModuleInterface/actor_objc.swift

@@ -15,6 +15,6 @@ import Foundation
 // CHECK-LABEL: @objc @_inheritsConvenienceInitializers
 // CHECK: public actor SomeActor : ObjectiveC.NSObject {
 // CHECK: @objc override public init()
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(SwiftStdlib 5.5, *)
 public actor SomeActor: NSObject {
 }

test/lit.cfg

@@ -408,7 +408,10 @@ config.swift_test_options = '-swift-version ' + swift_version
 
 # Define a macro for the next release OS version.
 # This macro can be used in code as `@available(SwiftStdlib 5.5, *)`.
-swift_stdlib_macro = '\'SwiftStdlib 5.5:macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0\''
+if 'back_deploy_concurrency' in lit_config.params:
+    swift_stdlib_macro = '\'SwiftStdlib 5.5:macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0\''
+else:
+    swift_stdlib_macro = '\'SwiftStdlib 5.5:macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0\''
 config.swift_frontend_test_options += ' -define-availability ' + swift_stdlib_macro
 config.swift_driver_test_options += ' -Xfrontend -define-availability -Xfrontend ' + swift_stdlib_macro