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

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

@@ -78,14 +78,14 @@ set(SwiftCore_VENDOR_MODULE_DIR "${SwiftCore_CMAKE_MODULES_DIR}/vendor"
 include(GNUInstallDirs)
 include(CheckSymbolExists)
 include(CheckIncludeFileCXX)
-include(AvailabilityMacros)
 include(CompilerSettings)
 include(DefaultSettings)
 include(EmitSwiftInterface)
 include(PlatformInfo)
 include(gyb)
 include(ResourceEmbedding)
 include(CatalystSupport)
+include(AvailabilityMacros)
 
 check_symbol_exists("asl_log" "asl.h" SwiftCore_HAS_ASL)
 check_symbol_exists("dladdr" "dlfcn.h" SwiftCore_HAS_DLADDR)
@@ -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 +5,32 @@ 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("${def}" MATCHES "SwiftStdlib .*")
+    # For each SwiftStdlib x.y, also define SwiftStdlibCurrentOS x.y, which,
+    # will expand to the current `-target` platform if the macro defines a
+    # newer platform as its availability.
+    #
+    # There is a setting, SwiftCore_ENABLE_STRICT_AVAILABILITY, which if set
+    # ON will cause us to use the "proper" availability instead.
+    string(REPLACE "SwiftStdlib" "SwiftStdlibCurrentOS" current "${def}")
+    if(NOT SwiftCore_ENABLE_STRICT_AVAILABILITY AND SwiftCore_SWIFT_AVAILABILITY_PLATFORM)
+      if(SwiftCore_SWIFT_AVAILABILITY_PLATFORM STREQUAL "macOS" and SwiftCore_VARIANT_AVAILABILITY_PLATFORM STREQUAL "iOS")
+        string(REGEX MATCH "iOS ([0-9]+(\.[0-9]+)+)" ios_platform_version "${def}")
+        string(REGEX MATCH "[0-9]+(\.[0-9]+)+" ios_version "${ios_platform_version}")
+        string(REGEX MATCH "macOS ([0-9]+(\.[0-9]+)+)" macos_platform_version "${def}")
+        string(REGEX MATCH "[0-9]+(\.[0-9]+)+" macos_version "${macos_platform_version}")
+        if((NOT macos_version STREQUAL "9999" OR NOT ios_version STREQUAL "9999") AND (macos_version VERSION_GREATER CMAKE_OSX_DEPLOYMENT_TARGET OR ios_version VERSION_GREATER SwiftCore_VARIANT_DEPLOYMENT_VERSION))
+          string(REGEX REPLACE ":.*" ": macOS ${CMAKE_OSX_DEPLOYMENT_VERSION}, iOS ${SwiftCore_VARIANT_DEPLOYMENT_VERSION}" current "${current}")
+        endif()
+      else()
+        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()
+    endif()
+    add_compile_options("$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -define-availability -Xfrontend \"${current}\">")
+  endif()
 endforeach()

Runtimes/Core/cmake/modules/CatalystSupport.cmake

@@ -34,5 +34,12 @@ if(SwiftCore_COMPILER_VARIANT_TARGET)
     set(SwiftCore_VARIANT_MODULE_TRIPLE "${module_triple}" CACHE STRING "Triple used for installed swift{module,interface} files for the target variant")
     mark_as_advanced(SwiftCore_VARIANT_MODULE_TRIPLE)
     message(CONFIGURE_LOG "Swift target variant module triple: ${module_triple}")
+
+    string(JSON triple GET "${target_info_json}" "target" "triple")
+    if(triple MATCHES "apple-([a-zA-Z]+)([0-9]+[.0-9]*)-macabi")
+      set(SwiftCore_VARIANT_DEPLOYMENT_VERSION "${CMAKE_MATCH_2}")
+      mark_as_advanced(SwiftCore_VARIANT_DEPLOYMENT_VERSION)
+      message(CONFIGURE_LOG "Swift target variant deployment version: ${SwiftCore_VARIANT_DEPLOYMENT_VERSION}")
+    endif()
   endif()
 endif()

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 +36,40 @@ if(NOT SwiftCore_ARCH_SUBDIR)
 
   message(CONFIGURE_LOG "Swift Arch: ${arch}")
 endif()
+
+set(availability_platform_macosx "macOS")
+set(availability_platform_ios "iOS")
+set(availability_platform_watchos "watchOS")
+set(availability_platform_tvos "tvOS")
+set(availability_platform_xros "visionOS")
+set(availability_platform_bridgeos "bridgeOS")
+
+if(NOT SwiftCore_SWIFT_AVAILABILITY_PLATFORM)
+  if(SwiftCore_SWIFT_MODULE_TRIPLE MATCHES ".*-([^-]+)-simulator$")
+    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 ${platform} for availability")
+  endif()
+endif()
+
+if(SwiftCore_VARIANT_MODULE_TRIPLE)
+  if(SwiftCore_VARIANT_MODULE_TRIPLE MATCHES ".*-([^-]+)$")
+    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_VARIANT_AVAILABILITY_PLATFORM "${availability_platform_${platform}}")
+  else()
+    message(ERROR "Unknown platform ${platform} for variant 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 +1003,41 @@ 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("${def}" MATCHES "SwiftStdlib .*")
+      # For each SwiftStdlib x.y, also define SwiftStdlibCurrentOS x.y, which,
+      # will expand to the current `-target` platform if the macro defines a
+      # newer platform as its availability.
+      #
+      # There is a setting, SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY, which if set
+      # ON will cause us to use the "proper" availability instead.
+      string(REPLACE "SwiftStdlib" "SwiftStdlibCurrentOS" current "${def}")
+      if(NOT SWIFT_STDLIB_ENABLE_STRICT_AVAILABILITY AND SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_AVAILABILITY_NAME)
+        if(SWIFTLIB_SINGLE_SDK STREQUAL "OSX" AND SWIFTLIB_SINGLE_MACCATALYST_BUILD_FLAVOR STREQUAL "ios-like")
+          string(REGEX MATCH "iOS ([0-9]+(\.[0-9]+)+)" platform_version "${def}")
+          string(REGEX MATCH "[0-9]+(\.[0-9]+)+" version "${platform_version}")
+          if(NOT version STREQUAL "9999" AND version VERSION_GREATER "${SWIFT_DARWIN_DEPLOYMENT_VERSION_MACCATALYST}")
+            string(REGEX REPLACE ":.*" ":iOS ${SWIFT_DARWIN_DEPLOYMENT_VERSION_MACCATALYST}" current "${current}")
+          endif()
+        elseif(SWIFTLIB_SINGLE_SDK STREQUAL "OSX" AND SWIFTLIB_SINGLE_MACCATALYST_BUILD_FLAVOR STREQUAL "zippered")
+          string(REGEX MATCH "iOS ([0-9]+(\.[0-9]+)+)" ios_platform_version "${def}")
+          string(REGEX MATCH "[0-9]+(\.[0-9]+)+" ios_version "${ios_platform_version}")
+          string(REGEX MATCH "macOS ([0-9]+(\.[0-9]+)+)" macos_platform_version "${def}")
+          string(REGEX MATCH "[0-9]+(\.[0-9]+)+" macos_version "${macos_platform_version}")
+          if((NOT macos_version STREQUAL "9999" OR NOT ios_version STREQUAL "9999") AND (macos_version VERSION_GREATER "${SWIFT_SDK_OSX_DEPLOYMENT_VERSION}" OR ios_version VERSION_GREATER "${SWIFT_DARWIN_DEPLOYMENT_VERSION_MACCATALYST}"))
+            string(REGEX REPLACE ":.*" ": macOS ${SWIFT_SDK_OSX_DEPLOYMENT_VERSION}, iOS ${SWIFT_DARWIN_DEPLOYMENT_VERSION_MACCATALYST}" current "${current}")
+          endif()
+        else()
+          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 "${current}")
+          endif()
+        endif()
+      endif()
+
+      list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS "-Xfrontend" "-define-availability" "-Xfrontend" "${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 {
 

stdlib/public/Concurrency/CMakeLists.txt

@@ -214,6 +214,13 @@ if((SWIFT_BUILD_CLANG_OVERLAYS
   set(SWIFT_CONCURRENCY_DEPENDENCIES _Builtin_float)
 endif()
 
+# Build with a minimum deployment target of 10.15
+if(SWIFT_DARWIN_DEPLOYMENT_VERSION_OSX VERSION_LESS "10.15")
+  set(osx_deployment_target "10.15")
+else()
+  set(osx_deployment_target "${SWIFT_DARWIN_DEPLOYMENT_VERSION_OSX}")
+endif()
+
 add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
   ${SWIFT_RUNTIME_CONCURRENCY_C_SOURCES}
   ${SWIFT_RUNTIME_CONCURRENCY_EXECUTOR_SOURCES}
@@ -240,6 +247,8 @@ add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
     ${swift_concurrency_incorporate_object_libraries_so}
   LINK_LIBRARIES ${swift_concurrency_link_libraries}
 
+  DEPLOYMENT_VERSION_OSX ${osx_deployment_target}
+
   C_COMPILE_FLAGS
     -Dswift_Concurrency_EXPORTS ${SWIFT_RUNTIME_CONCURRENCY_C_FLAGS}
     -I${SWIFT_SOURCE_DIR}/stdlib/include