[Concurrency][Stdlib] Add SwiftStdlibCurrentOS availability, use it.

If you use SwiftStdlibCurrentOS availability, you will be able to
use new types and functions from within the implementation. This
works by, when appropriate, building with the CurrentOS availability
set to the current deployment target.

rdar://148275746

Author: al45tair

CMakeLists.txt

@@ -462,6 +462,10 @@ option(SWIFT_STDLIB_ASSERTIONS
     "Enable internal checks for the Swift standard library (useful for debugging the library itself, does not affect checks required for safety)"
     "${SWIFT_STDLIB_ASSERTIONS_default}")
 
+option(SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY
+       "Enable strict availability; this will cause things to break at desk or in CI if the host OS is a lower version than some `@availability` annotations in the runtime code"
+       FALSE)
+
 option(SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER
        "Use the host compiler and not the internal clang to build the swift runtime"
        FALSE)
@@ -1404,8 +1408,9 @@ endif()
 
 if(SWIFT_BUILD_STDLIB OR SWIFT_BUILD_SDK_OVERLAY)
   message(STATUS "Building Swift standard library and overlays for SDKs: ${SWIFT_SDKS}")
-  message(STATUS "  Build type:       ${SWIFT_STDLIB_BUILD_TYPE}")
-  message(STATUS "  Assertions:       ${SWIFT_STDLIB_ASSERTIONS}")
+  message(STATUS "  Build type:               ${SWIFT_STDLIB_BUILD_TYPE}")
+  message(STATUS "  Assertions:               ${SWIFT_STDLIB_ASSERTIONS}")
+  message(STATUS "  Strict availability:      ${SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY}")
   message(STATUS "")
 
   message(STATUS "Building Swift runtime with:")

Runtimes/Core/CMakeLists.txt

@@ -125,6 +125,7 @@ defaulted_option(SwiftCore_ENABLE_BACKTRACING "Enable backtracing runtime suppor
 defaulted_set(SwiftCore_BACKTRACER_PATH STRING "Set a fixed path to the Swift backtracer")
 defaulted_option(SwiftCore_ENABLE_FATALERROR_BACKTRACE "Build stdlib fatalError with backtrace output")
 defaulted_option(SwiftCore_ENABLE_PRESPECIALIZATION "Enable generic metadata prespecialization")
+defaulted_option(SwiftCore_ENABLE_STRICT_AVAILABILITY "Enable strict availability; this will cause things to break at desk or in CI if the host OS is a lower version than some `@availability` annotations in the runtime code")
 
 option(SwiftCore_ENABLE_CLOBBER_FREED_OBJECTS "" OFF)
 option(SwiftCore_ENABLE_RUNTIME_LEAK_CHECKER "" OFF)

Runtimes/Core/cmake/caches/Vendors/Apple/apple-common.cmake

@@ -12,6 +12,8 @@ set(SwiftCore_ENABLE_VECTOR_TYPES ON CACHE BOOL "")
 set(SwiftCore_ENABLE_RUNTIME_FUNCTION_COUNTERS ON CACHE BOOL "")
 set(SwiftCore_ENABLE_BACKDEPLOYMENT_SUPPORT ON CACHE BOOL "")
 set(SwiftCore_ENABLE_FILESYSTEM_SUPPORT ON CACHE BOOL "")
+set(SwiftCore_ENABLE_STRICT_AVAILABILITY ON CACHE BOOL "")
+
 set(SwiftCore_OPTIMIZATION_REMARKS "bitstream" CACHE STRING "")
 
 set(SwiftCore_INSTALL_NESTED_SUBDIR OFF CACHE BOOL "")

Runtimes/Core/cmake/modules/AvailabilityMacros.cmake

@@ -5,4 +5,22 @@ file(STRINGS "${CMAKE_CURRENT_BINARY_DIR}/availability-macros.def" availability_
 list(FILTER availability_defs EXCLUDE REGEX "^\\s*(#.*)?$")
 foreach(def ${availability_defs})
   add_compile_options("$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -define-availability -Xfrontend \"${def}\">")
+
+  if("${def}" MATCHES "SwiftStdlib .*")
+    # For each SwiftStdlib x.y, also define SwiftStdlibTargetOS x.y, which,
+    # will expand to the current `-target` platform if the macro defines a
+    # newer platform as its availability.
+    #
+    # There is a setting, SwiftCore_ENABLE_STRICT_AVAILABILITY, which if set
+    # ON will cause us to use the "proper" availability instead.
+    string(REPLACE "SwiftStdlib" "SwiftStdlibCurrentOS" current "${def}")
+    if(NOT SwiftCore_ENABLE_STRICT_AVAILABILITY AND SwiftCore_SWIFT_AVAILABILITY_PLATFORM)
+      string(REGEX MATCH "${SwiftCore_SWIFT_AVAILABILITY_PLATFORM} ([0-9]+(\.[0-9]+)+)" platform_version "${def}")
+      string(REGEX MATCH "[0-9]+(\.[0-9]+)+" version "${platform_version}")
+      if(NOT version STREQUAL "9999" AND version VERSION_GREATER CMAKE_OSX_DEPLOYMENT_TARGET)
+        string(REGEX REPLACE ":.*" ":${SwiftCore_SWIFT_AVAILABILITY_PLATFORM} ${CMAKE_OSX_DEPLOYMENT_TARGET}" current "${current}")
+      endif()
+    endif()
+    add_compile_options("$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -define-availability -Xfrontend \"${current}\">")
+  endif()
 endforeach()

Runtimes/Core/cmake/modules/DefaultSettings.cmake

@@ -11,6 +11,8 @@ set(SwiftCore_ENABLE_COMMANDLINE_SUPPORT_default OFF) # TODO: enable this by def
 set(SwiftCore_ENABLE_STDIN_default ON)
 set(SwiftCore_ENABLE_TYPE_PRINTING_default ON)
 
+set(SwiftCore_ENABLE_STRICT_AVAILABILITY_default OFF)
+
 set(SwiftCore_BACKTRACER_PATH_default "")
 
 # Provide a boolean option that a user can optionally enable.
@@ -20,7 +22,7 @@ macro(defaulted_option variable helptext)
   if(NOT DEFINED ${variable}_default)
     set(${variable}_default OFF)
   endif()
-  option(${variable} ${helptext} ${${variable}_default})
+  option(${variable} "${helptext}" ${${variable}_default})
 endmacro()
 
 # Create a defaulted cache entry

Runtimes/Core/cmake/modules/PlatformInfo.cmake

@@ -36,3 +36,26 @@ if(NOT SwiftCore_ARCH_SUBDIR)
 
   message(CONFIGURE_LOG "Swift Arch: ${arch}")
 endif()
+
+if(NOT SwiftCore_SWIFT_AVAILABILITY_PLATFORM)
+  set(availability_platform_macosx "macOS")
+  set(availability_platform_ios "iOS")
+  set(availability_platform_watchos "watchOS")
+  set(availability_platform_tvos "tvOS")
+  set(availability_platform_xros "visionOS")
+  set(availability_platform_bridgeos "bridgeOS")
+
+  if(SwiftCore_SWIFT_MODULE_TRIPLE MATCHES ".*-([^-]+)-simulator$")
+    set(platform "${CMAKE_MATCH_1}")
+  elseif(SwiftCore_SWIFT_MODULE_TRIPLE MATCHES ".*-([^-]+)$")
+    set(platform "${CMAKE_MATCH_1}")
+  else()
+    message(ERROR "Unable to extract platform name from triple ${SwiftCore_SWIFT_MODULE_TRIPLE}")
+  endif()
+
+  if(availability_platform_${platform})
+    set(SwiftCore_SWIFT_AVAILABILITY_PLATFORM "${availability_platform_${platform}}")
+  else()
+    message(ERROR "Unknown platform ${platform} for availability")
+  endif()
+endif()

cmake/modules/DarwinSDKs.cmake

@@ -12,7 +12,7 @@ is_sdk_requested(OSX swift_build_osx)
 if(swift_build_osx)
   configure_sdk_darwin(
       OSX "OS X" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_OSX}"
-      macosx macosx macos "${SUPPORTED_OSX_ARCHS}")
+      macosx macosx macos macOS "${SUPPORTED_OSX_ARCHS}")
   configure_target_variant(OSX-DA "OS X Debug+Asserts"   OSX DA "Debug+Asserts")
   configure_target_variant(OSX-RA "OS X Release+Asserts" OSX RA "Release+Asserts")
   configure_target_variant(OSX-R  "OS X Release"         OSX R  "Release")
@@ -26,12 +26,15 @@ if(swift_build_freestanding AND (SWIFT_FREESTANDING_FLAVOR STREQUAL "apple"))
       "Which triple name (e.g. 'none-macho') to use when building the FREESTANDING stdlib")
   set(SWIFT_FREESTANDING_MODULE_NAME "" CACHE STRING
       "Which .swiftmodule name (e.g. 'freestanding') to use when building the FREESTANDING stdlib")
+  set(SWIFT_FREESTANDING_AVAILABILITY_NAME "" CACHE STRING
+      "Which @availability name (e.g. 'macOS') to use when building the FREESTANDING stdlib")
   set(SWIFT_FREESTANDING_ARCHS "" CACHE STRING
       "Which architectures to build when building the FREESTANDING stdlib")
   configure_sdk_darwin(
       FREESTANDING "FREESTANDING" ""
       "${SWIFT_FREESTANDING_SDK}"
-      "${SWIFT_FREESTANDING_TRIPLE_NAME}" "${SWIFT_FREESTANDING_MODULE_NAME}" "${SWIFT_FREESTANDING_ARCHS}")
+      "${SWIFT_FREESTANDING_TRIPLE_NAME}" "${SWIFT_FREESTANDING_MODULE_NAME}"
+      "${SWIFT_FREESTANDING_AVAILABILITY_NAME}" "${SWIFT_FREESTANDING_ARCHS}")
   set(SWIFT_SDK_FREESTANDING_LIB_SUBDIR "freestanding")
   configure_target_variant(FREESTANDING-DA "FREESTANDING Debug+Asserts"   FREESTANDING DA "Debug+Asserts")
   configure_target_variant(FREESTANDING-RA "FREESTANDING Release+Asserts" FREESTANDING RA "Release+Asserts")
@@ -53,7 +56,7 @@ is_sdk_requested(IOS swift_build_ios)
 if(swift_build_ios)
   configure_sdk_darwin(
       IOS "iOS" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_IOS}"
-      iphoneos ios ios "${SUPPORTED_IOS_ARCHS}")
+      iphoneos ios ios iOS "${SUPPORTED_IOS_ARCHS}")
   configure_target_variant(IOS-DA "iOS Debug+Asserts"   IOS DA "Debug+Asserts")
   configure_target_variant(IOS-RA "iOS Release+Asserts" IOS RA "Release+Asserts")
   configure_target_variant(IOS-R  "iOS Release"         IOS R "Release")
@@ -63,7 +66,7 @@ is_sdk_requested(IOS_SIMULATOR swift_build_ios_simulator)
 if(swift_build_ios_simulator)
   configure_sdk_darwin(
       IOS_SIMULATOR "iOS Simulator" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_IOS}"
-      iphonesimulator ios ios-simulator
+      iphonesimulator ios ios-simulator iOS
       "${SUPPORTED_IOS_SIMULATOR_ARCHS}")
   configure_target_variant(
       IOS_SIMULATOR-DA "iOS Debug+Asserts"   IOS_SIMULATOR DA "Debug+Asserts")
@@ -77,7 +80,7 @@ is_sdk_requested(TVOS swift_build_tvos)
 if(swift_build_tvos)
   configure_sdk_darwin(
       TVOS "tvOS" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_TVOS}"
-      appletvos tvos tvos "${SUPPORTED_TVOS_ARCHS}")
+      appletvos tvos tvos tvOS "${SUPPORTED_TVOS_ARCHS}")
   configure_target_variant(TVOS-DA "tvOS Debug+Asserts"   TVOS DA "Debug+Asserts")
   configure_target_variant(TVOS-RA "tvOS Release+Asserts" TVOS RA "Release+Asserts")
   configure_target_variant(TVOS-R  "tvOS Release"         TVOS R "Release")
@@ -87,7 +90,7 @@ is_sdk_requested(TVOS_SIMULATOR swift_build_tvos_simulator)
 if(swift_build_tvos_simulator)
   configure_sdk_darwin(
       TVOS_SIMULATOR "tvOS Simulator" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_TVOS}"
-      appletvsimulator tvos tvos-simulator
+      appletvsimulator tvos tvos-simulator tvOS
       "${SUPPORTED_TVOS_SIMULATOR_ARCHS}")
   configure_target_variant(
     TVOS_SIMULATOR-DA "tvOS Debug+Asserts"   TVOS_SIMULATOR DA "Debug+Asserts")
@@ -101,7 +104,7 @@ is_sdk_requested(WATCHOS swift_build_watchos)
 if(swift_build_watchos)
   configure_sdk_darwin(
       WATCHOS "watchOS" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_WATCHOS}"
-      watchos watchos watchos "${SUPPORTED_WATCHOS_ARCHS}")
+      watchos watchos watchos watchOS "${SUPPORTED_WATCHOS_ARCHS}")
   configure_target_variant(WATCHOS-DA "watchOS Debug+Asserts"   WATCHOS DA "Debug+Asserts")
   configure_target_variant(WATCHOS-RA "watchOS Release+Asserts" WATCHOS RA "Release+Asserts")
   configure_target_variant(WATCHOS-R  "watchOS Release"         WATCHOS R "Release")
@@ -111,7 +114,7 @@ is_sdk_requested(WATCHOS_SIMULATOR swift_build_watchos_simulator)
 if(swift_build_watchos_simulator)
   configure_sdk_darwin(
       WATCHOS_SIMULATOR "watchOS Simulator" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_WATCHOS}"
-      watchsimulator watchos watchos-simulator
+      watchsimulator watchos watchos-simulator watchOS
       "${SUPPORTED_WATCHOS_SIMULATOR_ARCHS}")
   configure_target_variant(WATCHOS_SIMULATOR-DA "watchOS Debug+Asserts"   WATCHOS_SIMULATOR DA "Debug+Asserts")
   configure_target_variant(WATCHOS_SIMULATOR-RA "watchOS Release+Asserts" WATCHOS_SIMULATOR RA "Release+Asserts")
@@ -122,7 +125,7 @@ is_sdk_requested(XROS swift_build_xros)
 if(swift_build_xros)
   configure_sdk_darwin(
       XROS "xrOS" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_XROS}"
-      xros xros xros "${SUPPORTED_XROS_ARCHS}")
+      xros xros xros visionOS "${SUPPORTED_XROS_ARCHS}")
   configure_target_variant(XROS-DA "xrOS Debug+Asserts"   XROS DA "Debug+Asserts")
   configure_target_variant(XROS-RA "xrOS Release+Asserts" XROS RA "Release+Asserts")
   configure_target_variant(XROS-R  "xrOS Release"         XROS R "Release")
@@ -132,7 +135,7 @@ is_sdk_requested(XROS_SIMULATOR swift_build_xros_simulator)
 if(swift_build_xros_simulator)
   configure_sdk_darwin(
       XROS_SIMULATOR "xrOS Simulator" "${SWIFT_DARWIN_DEPLOYMENT_VERSION_XROS}"
-      xrsimulator xros xros-simulator
+      xrsimulator xros xros-simulator visionOS
       "${SUPPORTED_XROS_SIMULATOR_ARCHS}")
 
   configure_target_variant(

cmake/modules/SwiftConfigureSDK.cmake

@@ -136,6 +136,7 @@ endfunction()
 #     deployment_version # Deployment version
 #     xcrun_name         # SDK name to use with xcrun
 #     triple_name        # The name used in Swift's -triple
+#     availability_name  # The name used in Swift's @availability
 #     architectures      # A list of architectures this SDK supports
 #   )
 #
@@ -165,9 +166,11 @@ endfunction()
 #   SWIFT_SDK_${prefix}_ARCH_${ARCH}_TRIPLE       Triple name
 #   SWIFT_SDK_${prefix}_ARCH_${ARCH}_MODULE       Module triple name for this SDK
 #   SWIFT_SDK_${prefix}_USE_BUILD_ID              Whether to pass --build-id to the linker
+#   SWIFT_SDK_${prefix}_AVAILABILITY_NAME       Name to use in @availability
+#
 macro(configure_sdk_darwin
     prefix name deployment_version xcrun_name
-    triple_name module_name architectures)
+    triple_name module_name availability_name architectures)
   # Note: this has to be implemented as a macro because it sets global
   # variables.
 
@@ -201,6 +204,7 @@ macro(configure_sdk_darwin
   set(SWIFT_SDK_${prefix}_DEPLOYMENT_VERSION "${deployment_version}")
   set(SWIFT_SDK_${prefix}_LIB_SUBDIR "${xcrun_name}")
   set(SWIFT_SDK_${prefix}_TRIPLE_NAME "${triple_name}")
+  set(SWIFT_SDK_${prefix}_AVAILABILITY_NAME "${availability_name}")
   set(SWIFT_SDK_${prefix}_OBJECT_FORMAT "MACHO")
   set(SWIFT_SDK_${prefix}_USE_ISYSROOT TRUE)
   set(SWIFT_SDK_${prefix}_SHARED_LIBRARY_PREFIX "lib")

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -1003,6 +1003,25 @@ function(add_swift_target_library_single target name)
   # Define availability macros.
   foreach(def ${SWIFT_STDLIB_AVAILABILITY_DEFINITIONS})
     list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS "-Xfrontend" "-define-availability" "-Xfrontend" "${def}")
+
+    if("${def}" MATCHES "SwiftStdlib .*")
+      # For each SwiftStdlib x.y, also define SwiftStdlibTargetOS x.y, which,
+      # will expand to the current `-target` platform if the macro defines a
+      # newer platform as its availability.
+      #
+      # There is a setting, SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY, which if set
+      # ON will cause us to use the "proper" availability instead.
+      string(REPLACE "SwiftStdlib" "SwiftStdlibCurrentOS" current "${def}")
+      if(NOT SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY AND SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_AVAILABILITY_NAME)
+        string(REGEX MATCH "${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_AVAILABILITY_NAME} ([0-9]+(\.[0-9]+)+)" platform_version "${def}")
+        string(REGEX MATCH "[0-9]+(\.[0-9]+)+" version "${platform_version}")
+        if(NOT version STREQUAL "9999" AND version VERSION_GREATER "${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_DEPLOYMENT_VERSION}")
+          string(REGEX REPLACE ":.*" ":${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_AVAILABILITY_NAME} ${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_DEPLOYMENT_VERSION}" current "${current}")
+        endif()
+      endif()
+
+      list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS "-Xfrontend" "-define-availability" "-Xfrontend" "${current}")
+    endif()
   endforeach()
 
   # Enable -target-min-inlining-version

stdlib/public/Concurrency/CFExecutor.swift

@@ -43,7 +43,7 @@ enum CoreFoundation {
 
 // .. Main Executor ............................................................
 
-@available(SwiftStdlib 6.2, *)
+@available(SwiftStdlibCurrentOS 6.2, *)
 public final class CFMainExecutor: DispatchMainExecutor, @unchecked Sendable {
 
   override public func run() throws {
@@ -58,7 +58,7 @@ public final class CFMainExecutor: DispatchMainExecutor, @unchecked Sendable {
 
 // .. Task Executor ............................................................
 
-@available(SwiftStdlib 6.2, *)
+@available(SwiftStdlibCurrentOS 6.2, *)
 public final class CFTaskExecutor: DispatchGlobalTaskExecutor,
                                    @unchecked Sendable {