Merge pull request #80680 from slavapestov/compatibility-span-6.2

[6.2] Cherry-pick recent CompatibilitySpan work
2025-12-14 20:36:38 +01:00 · 2025-04-23 01:00:29 -04:00
parent cbb0347bea d62e385254
commit a10356aa27
17 changed files with 266 additions and 70 deletions
--- a/Runtimes/Core/cmake/modules/AvailabilityMacros.cmake
+++ b/Runtimes/Core/cmake/modules/AvailabilityMacros.cmake
@@ -1,4 +1,7 @@
-file(STRINGS "${SwiftCore_SWIFTC_SOURCE_DIR}/utils/availability-macros.def" availability_defs)
+configure_file("${SwiftCore_SWIFTC_SOURCE_DIR}/utils/availability-macros.def"
+               "${CMAKE_CURRENT_BINARY_DIR}/availability-macros.def"
+               COPYONLY)
+file(STRINGS "${CMAKE_CURRENT_BINARY_DIR}/availability-macros.def" availability_defs)
 list(FILTER availability_defs EXCLUDE REGEX "^\\s*(#.*)?$")
 foreach(def ${availability_defs})
  add_compile_options("$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -define-availability -Xfrontend \"${def}\">")
--- a/Runtimes/Core/core/CMakeLists.txt
+++ b/Runtimes/Core/core/CMakeLists.txt
@@ -301,7 +301,8 @@ target_compile_options(swiftCore PRIVATE
  $<$<COMPILE_LANGUAGE:Swift>:-nostdimport>
  "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -group-info-path -Xfrontend ${CMAKE_CURRENT_SOURCE_DIR}/GroupInfo.json>"
  "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -disable-objc-attr-requires-foundation-module>"
-  "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -require-explicit-availability=ignore>")
+  "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -require-explicit-availability=ignore>"
+  "$<$<AND:$<PLATFORM_ID:Darwin>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -previous-module-installname-map-file -Xfrontend ${CMAKE_CURRENT_SOURCE_DIR}/PreviousModuleInstallName.json>")
 if(NOT "${CMAKE_BUILD_TYPE}" STREQUAL "MinSizeRel")
  # Using these in MinSizeRel would result in a 15% increase in the binary size
  target_compile_options(swiftCore PRIVATE
--- a/include/swift/AST/RuntimeVersions.def
+++ b/include/swift/AST/RuntimeVersions.def
@@ -152,7 +152,10 @@ RUNTIME_VERSION(

 RUNTIME_VERSION(
  (6, 1),
-  FUTURE
+  PLATFORM(macOS,   (15, 4, 0))
+  PLATFORM(iOS,     (18, 4, 0))
+  PLATFORM(watchOS, (11, 4, 0))
+  PLATFORM(visionOS,(2, 4, 0))
 )

 RUNTIME_VERSION(
--- a/stdlib/cmake/modules/AddSwiftStdlib.cmake
+++ b/stdlib/cmake/modules/AddSwiftStdlib.cmake
@@ -721,6 +721,8 @@ endfunction()
 #     [DONT_EMBED_BITCODE]
 #     [IS_STDLIB]
 #     [IS_STDLIB_CORE]
+#     [ONLY_SWIFTMODULE]
+#     [NO_SWIFTMODULE]
 #     [IS_SDK_OVERLAY]
 #     [IS_FRAGILE]
 #     INSTALL_IN_COMPONENT comp
@@ -742,9 +744,6 @@ endfunction()
 # STATIC
 #   Build a static library.
 #
-# ONLY_SWIFTMODULE
-#   Do not build either static or shared, build just the .swiftmodule.
-#
 # SDK sdk
 #   SDK to build for.
 #
@@ -784,6 +783,12 @@ endfunction()
 # IS_STDLIB_CORE
 #   Compile as the standard library core.
 #
+# ONLY_SWIFTMODULE
+#   Do not build either static or shared, build just the .swiftmodule.
+#
+# NO_SWIFTMODULE
+#   Only build either static or shared, and skip the .swiftmodule.
+#
 # IS_SDK_OVERLAY
 #   Treat the library as a part of the Swift SDK overlay.
 #
@@ -811,6 +816,7 @@ function(add_swift_target_library_single target name)
        SHARED
        STATIC
        ONLY_SWIFTMODULE
+        NO_SWIFTMODULE
        NO_LINK_NAME
        INSTALL_WITH_SHARED
        IS_FRAGILE)
@@ -1035,6 +1041,7 @@ function(add_swift_target_library_single target name)
      ${SWIFTLIB_SINGLE_IS_SDK_OVERLAY_keyword}
      ${SWIFTLIB_SINGLE_IS_FRAGILE_keyword}
      ${SWIFTLIB_SINGLE_ONLY_SWIFTMODULE_keyword}
+      ${SWIFTLIB_SINGLE_NO_SWIFTMODULE_keyword}
      ${embed_bitcode_arg}
      ${SWIFTLIB_SINGLE_STATIC_keyword}
      ${SWIFTLIB_SINGLE_NO_LINK_NAME_keyword}
@@ -1686,6 +1693,8 @@ endfunction()
 #     [INSTALL]
 #     [IS_STDLIB]
 #     [IS_STDLIB_CORE]
+#     [ONLY_SWIFTMODULE]
+#     [NO_SWIFTMODULE]
 #     [INSTALL_WITH_SHARED]
 #     INSTALL_IN_COMPONENT comp
 #     DEPLOYMENT_VERSION_OSX version
@@ -1794,6 +1803,12 @@ endfunction()
 # IS_STDLIB_CORE
 #   Compile as the Swift standard library core.
 #
+# ONLY_SWIFTMODULE
+#   Do not build either static or shared, build just the .swiftmodule.
+#
+# NO_SWIFTMODULE
+#   Only build either static or shared, and skip the .swiftmodule.
+#
 # IS_SDK_OVERLAY
 #   Treat the library as a part of the Swift SDK overlay.
 #
@@ -1882,6 +1897,8 @@ function(add_swift_target_library name)
        IS_STDLIB_CORE
        IS_SWIFT_ONLY
        NOSWIFTRT
+        ONLY_SWIFTMODULE
+        NO_SWIFTMODULE
        OBJECT_LIBRARY
        SHARED
        STATIC
@@ -2493,6 +2510,8 @@ function(add_swift_target_library name)
        ${SWIFTLIB_IS_STDLIB_CORE_keyword}
        ${SWIFTLIB_IS_SDK_OVERLAY_keyword}
        ${SWIFTLIB_NOSWIFTRT_keyword}
+        ${SWIFTLIB_ONLY_SWIFTMODULE_keyword}
+        ${SWIFTLIB_NO_SWIFTMODULE_keyword}
        DARWIN_INSTALL_NAME_DIR "${SWIFTLIB_DARWIN_INSTALL_NAME_DIR}"
        INSTALL_IN_COMPONENT "${SWIFTLIB_INSTALL_IN_COMPONENT}"
        DEPLOYMENT_VERSION_OSX "${SWIFTLIB_DEPLOYMENT_VERSION_OSX}"
--- a/stdlib/cmake/modules/SwiftSource.cmake
+++ b/stdlib/cmake/modules/SwiftSource.cmake
@@ -49,7 +49,7 @@ function(handle_swift_sources
    dependency_sibgen_target_out_var_name
    sourcesvar externalvar name)
  cmake_parse_arguments(SWIFTSOURCES
-      "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;NO_LINK_NAME;IS_FRAGILE;ONLY_SWIFTMODULE"
+      "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;NO_LINK_NAME;IS_FRAGILE;ONLY_SWIFTMODULE;NO_SWIFTMODULE"
      "SDK;ARCHITECTURE;INSTALL_IN_COMPONENT;DEPLOYMENT_VERSION_OSX;DEPLOYMENT_VERSION_IOS;DEPLOYMENT_VERSION_TVOS;DEPLOYMENT_VERSION_WATCHOS;MACCATALYST_BUILD_FLAVOR;BOOTSTRAPPING;INSTALL_BINARY_SWIFTMODULE"
      "DEPENDS;COMPILE_FLAGS;MODULE_NAME;MODULE_DIR;ENABLE_LTO"
      ${ARGN})
@@ -66,6 +66,7 @@ function(handle_swift_sources
  translate_flag(${SWIFTSOURCES_NO_LINK_NAME} "NO_LINK_NAME" NO_LINK_NAME_arg)
  translate_flag(${SWIFTSOURCES_IS_FRAGILE} "IS_FRAGILE" IS_FRAGILE_arg)
  translate_flag(${SWIFTSOURCES_ONLY_SWIFTMODULE} "ONLY_SWIFTMODULE" ONLY_SWIFTMODULE_arg)
+  translate_flag(${SWIFTSOURCES_NO_SWIFTMODULE} "NO_SWIFTMODULE" NO_SWIFTMODULE_arg)
  if(DEFINED SWIFTSOURCES_BOOTSTRAPPING)
    set(BOOTSTRAPPING_arg "BOOTSTRAPPING" ${SWIFTSOURCES_BOOTSTRAPPING})
  endif()
@@ -161,6 +162,7 @@ function(handle_swift_sources
        ${BOOTSTRAPPING_arg}
        ${IS_FRAGILE_arg}
        ${ONLY_SWIFTMODULE_arg}
+        ${NO_SWIFTMODULE_arg}
        INSTALL_BINARY_SWIFTMODULE ${SWIFTSOURCES_INSTALL_BINARY_SWIFTMODULE}
        INSTALL_IN_COMPONENT "${SWIFTSOURCES_INSTALL_IN_COMPONENT}"
        DEPLOYMENT_VERSION_OSX ${SWIFTSOURCES_DEPLOYMENT_VERSION_OSX}
@@ -405,6 +407,8 @@ endfunction()
 #     [IS_MAIN]                         # This is an executable, not a library
 #     [IS_STDLIB]
 #     [IS_STDLIB_CORE]                  # This is the core standard library
+#     [ONLY_SWIFTMODULE]                # Emit swiftmodule only, no binary
+#     [NO_SWIFTMODULE]                  # Emit binary only, no swiftmodule
 #     [OPT_FLAGS]                       # Optimization flags (overrides SWIFT_OPTIMIZE)
 #     [MODULE_DIR]                      # Put .swiftmodule, .swiftdoc., and .o
 #                                       # into this directory.
@@ -419,7 +423,7 @@ function(_compile_swift_files
    dependency_sib_target_out_var_name dependency_sibopt_target_out_var_name
    dependency_sibgen_target_out_var_name)
  cmake_parse_arguments(SWIFTFILE
-    "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;IS_FRAGILE;ONLY_SWIFTMODULE"
+    "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;IS_FRAGILE;ONLY_SWIFTMODULE;NO_SWIFTMODULE"
    "OUTPUT;MODULE_NAME;INSTALL_IN_COMPONENT;DEPLOYMENT_VERSION_OSX;DEPLOYMENT_VERSION_IOS;DEPLOYMENT_VERSION_TVOS;DEPLOYMENT_VERSION_WATCHOS;MACCATALYST_BUILD_FLAVOR;BOOTSTRAPPING;INSTALL_BINARY_SWIFTMODULE"
    "SOURCES;FLAGS;DEPENDS;SDK;ARCHITECTURE;OPT_FLAGS;MODULE_DIR"
    ${ARGN})
@@ -678,6 +682,10 @@ function(_compile_swift_files
  get_bootstrapping_path(lib_dir ${SWIFTLIB_DIR} "${SWIFTFILE_BOOTSTRAPPING}")

  if(NOT SWIFTFILE_IS_MAIN)
+    list(APPEND swift_flags "-parse-as-library")
+  endif()
+
+  if(NOT SWIFTFILE_IS_MAIN AND NOT SWIFTFILE_NO_SWIFTMODULE)
    # Determine the directory where the module file should be placed.
    if(SWIFTFILE_MODULE_DIR)
      set(module_dir "${SWIFTFILE_MODULE_DIR}")
@@ -687,8 +695,6 @@ function(_compile_swift_files
      message(FATAL_ERROR "Don't know where to put the module files")
    endif()

-    list(APPEND swift_flags "-parse-as-library")
-
    set(module_base "${module_dir}/${SWIFTFILE_MODULE_NAME}")

    set(module_dir_static "${SWIFTSTATICLIB_DIR}/${library_subdir}")
@@ -1068,7 +1074,7 @@ function(_compile_swift_files
  #
  # We only build these when we are not producing a main file. We could do this
  # with sib/sibgen, but it is useful for looking at the stdlib.
-  if (NOT SWIFTFILE_IS_MAIN)
+  if (NOT SWIFTFILE_IS_MAIN AND NOT SWIFTFILE_NO_SWIFTMODULE)
    add_custom_command_target(
        module_dependency_target
        COMMAND
--- a/stdlib/public/core/PreviousModuleInstallName.json
+++ b/stdlib/public/core/PreviousModuleInstallName.json
@@ -1,6 +1,6 @@
 [
  {
    "module": "CompatibilitySpan",
-    "install_name": "/usr/lib/swift/libswiftCompatibilitySpan.dylib"
+    "install_name": "@rpath/libswiftCompatibilitySpan.dylib"
  }
 ]
--- a/stdlib/public/core/Span/MutableRawSpan.swift
+++ b/stdlib/public/core/Span/MutableRawSpan.swift
@@ -10,11 +10,16 @@
 //
 //===----------------------------------------------------------------------===//

+#if SPAN_COMPATIBILITY_STUB
+import Swift
+#endif
+
 // A MutableRawSpan represents a span of memory which
 // contains initialized `Element` instances.
@safe
@frozen
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 public struct MutableRawSpan: ~Copyable & ~Escapable {
  @usableFromInline
  internal let _pointer: UnsafeMutableRawPointer?
@@ -40,10 +45,12 @@ public struct MutableRawSpan: ~Copyable & ~Escapable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan: @unchecked Sendable {}

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  @unsafe
@@ -115,7 +122,8 @@ extension MutableRawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {
  @_alwaysEmitIntoClient
  public var byteCount: Int { _count }
@@ -129,7 +137,8 @@ extension MutableRawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  @_alwaysEmitIntoClient
@@ -154,7 +163,8 @@ extension MutableRawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  @_alwaysEmitIntoClient
@@ -166,7 +176,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  public var bytes: RawSpan {
@@ -202,7 +213,8 @@ extension MutableRawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  /// Returns a new instance of the given type, constructed from the raw memory
@@ -338,8 +350,13 @@ extension MutableRawSpan {
  }
 }

+// FIXME: The functions in this extension crash the SIL optimizer when built inside
+// the stub. But these declarations don't generate a public symbol anyway.
+#if !SPAN_COMPATIBILITY_STUB
+
 //MARK: copyMemory
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  @_alwaysEmitIntoClient
@@ -429,9 +446,11 @@ extension MutableRawSpan {
    update(fromContentsOf: source.bytes)
  }
 }
+#endif

 // MARK: sub-spans
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  /// Constructs a new span over the items within the supplied range of
@@ -546,7 +565,8 @@ extension MutableRawSpan {
 }

 // MARK: prefixes and suffixes
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableRawSpan {

  /// Returns a span containing the initial elements of this span,
--- a/stdlib/public/core/Span/MutableSpan.swift
+++ b/stdlib/public/core/Span/MutableSpan.swift
@@ -10,11 +10,16 @@
 //
 //===----------------------------------------------------------------------===//

+#if SPAN_COMPATIBILITY_STUB
+import Swift
+#endif
+
 // A MutableSpan<Element> represents a span of memory which
 // contains initialized `Element` instances.
@safe
@frozen
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 public struct MutableSpan<Element: ~Copyable>
 : ~Copyable, ~Escapable {
  @usableFromInline
@@ -41,10 +46,12 @@ public struct MutableSpan<Element: ~Copyable>
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan: @unchecked Sendable where Element: Sendable {}

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  @unsafe
@@ -87,7 +94,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan {

  @unsafe
@@ -102,7 +110,8 @@ extension MutableSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: BitwiseCopyable {

  @unsafe
@@ -154,7 +163,8 @@ extension MutableSpan where Element: BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {

  @_alwaysEmitIntoClient
@@ -170,7 +180,8 @@ extension Span where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  @_alwaysEmitIntoClient
@@ -182,7 +193,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  @_alwaysEmitIntoClient
@@ -198,7 +210,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  @_alwaysEmitIntoClient
@@ -211,7 +224,8 @@ extension MutableSpan where Element: ~Copyable {
 }

 //MARK: Collection, RandomAccessCollection
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  @_alwaysEmitIntoClient
@@ -228,7 +242,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: BitwiseCopyable {

  /// Construct a RawSpan over the memory represented by this span
@@ -243,7 +258,8 @@ extension MutableSpan where Element: BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  /// Accesses the element at the specified position in the `Span`.
@@ -296,7 +312,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  @_alwaysEmitIntoClient
@@ -319,7 +336,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: BitwiseCopyable {

  /// Accesses the element at the specified position in the `Span`.
@@ -368,7 +386,8 @@ extension MutableSpan where Element: BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  //FIXME: mark closure parameter as non-escaping
@@ -399,7 +418,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: BitwiseCopyable {

  //FIXME: mark closure parameter as non-escaping
@@ -425,7 +445,8 @@ extension MutableSpan where Element: BitwiseCopyable {
 }

 //MARK: bulk-update functions
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan {

  @_alwaysEmitIntoClient
@@ -510,7 +531,8 @@ extension MutableSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

 //  @_alwaysEmitIntoClient
@@ -543,7 +565,8 @@ extension MutableSpan where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan {

  @_alwaysEmitIntoClient
@@ -555,7 +578,8 @@ extension MutableSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: BitwiseCopyable {

  @_alwaysEmitIntoClient
@@ -649,7 +673,8 @@ extension MutableSpan where Element: BitwiseCopyable {
 }

 // MARK: sub-spans
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  /// Constructs a new span over the items within the supplied range of
@@ -767,7 +792,8 @@ extension MutableSpan where Element: ~Copyable {
 }

 // MARK: prefixes and suffixes
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension MutableSpan where Element: ~Copyable {

  /// Returns a span containing the initial elements of this span,
--- a/stdlib/public/core/Span/RawSpan.swift
+++ b/stdlib/public/core/Span/RawSpan.swift
@@ -22,7 +22,8 @@ import Swift
 /// owning the contiguous memory, ensuring temporal safety and avoiding
 /// use-after-free errors. Operations on `RawSpan` are bounds-checked,
 /// ensuring spcial safety and avoiding buffer overflow errors.
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
@frozen
@safe
 public struct RawSpan: ~Escapable, Copyable, BitwiseCopyable {
@@ -84,10 +85,12 @@ public struct RawSpan: ~Escapable, Copyable, BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan: @unchecked Sendable {}

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// Unsafely create a `RawSpan` over initialized memory.
@@ -326,7 +329,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// The number of bytes in the span.
@@ -355,7 +359,8 @@ extension RawSpan {
 }

 // MARK: extracting sub-spans
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// Constructs a new span over the bytes within the supplied range of
@@ -468,7 +473,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// Calls the given closure with a pointer to the underlying bytes of
@@ -498,7 +504,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// View the bytes of this span as type `T`
@@ -530,7 +537,8 @@ extension RawSpan {
 }

 // MARK: load
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// Returns a new instance of the given type, constructed from the raw memory
@@ -646,7 +654,8 @@ extension RawSpan {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {
  /// Returns a Boolean value indicating whether two `RawSpan` instances
  /// refer to the same region in memory.
@@ -678,7 +687,8 @@ extension RawSpan {
 }

 // MARK: prefixes and suffixes
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension RawSpan {

  /// Returns a span containing the initial bytes of this span,
--- a/stdlib/public/core/Span/Span.swift
+++ b/stdlib/public/core/Span/Span.swift
@@ -24,7 +24,8 @@ import Swift
 /// ensuring spcial safety and avoiding buffer overflow errors.
@frozen
@safe
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 public struct Span<Element: ~Copyable>: ~Escapable, Copyable, BitwiseCopyable {

  /// The starting address of this `Span`.
@@ -85,10 +86,12 @@ public struct Span<Element: ~Copyable>: ~Escapable, Copyable, BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span: @unchecked Sendable where Element: Sendable & ~Copyable {}

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {

  /// Unsafely create a `Span` over initialized memory.
@@ -165,7 +168,8 @@ extension Span where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span /*where Element: Copyable*/ {

  /// Unsafely create a `Span` over initialized memory.
@@ -211,7 +215,8 @@ extension Span /*where Element: Copyable*/ {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: BitwiseCopyable {

  /// Unsafely create a `Span` over initialized memory.
@@ -374,7 +379,8 @@ extension Span where Element: BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {

  /// The number of elements in the span.
@@ -406,7 +412,8 @@ extension Span where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {
  @_semantics("fixed_storage.check_index")
  @inline(__always)
@@ -459,7 +466,8 @@ extension Span where Element: ~Copyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: BitwiseCopyable {
  /// Accesses the element at the specified position in the `Span`.
  ///
@@ -509,7 +517,8 @@ extension Span where Element: BitwiseCopyable {
 }

 // MARK: sub-spans
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {

  /// Constructs a new span over the items within the supplied range of
@@ -628,7 +637,8 @@ extension Span where Element: ~Copyable {
 }

 // MARK: UnsafeBufferPointer access hatch
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable  {

  /// Calls a closure with a pointer to the viewed contiguous storage.
@@ -661,7 +671,8 @@ extension Span where Element: ~Copyable  {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: BitwiseCopyable {

  /// Calls the given closure with a pointer to the underlying bytes of
@@ -693,7 +704,8 @@ extension Span where Element: BitwiseCopyable {
  }
 }

-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {
  /// Returns a Boolean value indicating whether two `Span` instances
  /// refer to the same region in memory.
@@ -728,7 +740,8 @@ extension Span where Element: ~Copyable {
 }

 // MARK: prefixes and suffixes
-@available(SwiftStdlib 6.2, *)
+@available(SwiftCompatibilitySpan 5.0, *)
+@_originallyDefinedIn(module: "Swift;CompatibilitySpan", SwiftCompatibilitySpan 6.2)
 extension Span where Element: ~Copyable {

  /// Returns a span containing the initial elements of this span,
--- a/stdlib/toolchain/CompatibilitySpan/CMakeLists.txt
+++ b/stdlib/toolchain/CompatibilitySpan/CMakeLists.txt
@@ -4,6 +4,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin" AND DEFINED SWIFT_STDLIB_LIBRARY_BUILD_TY

  add_swift_target_library("${library_name}" ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
    FakeStdlib.swift
+    ../../public/core/Span/MutableRawSpan.swift
+    ../../public/core/Span/MutableSpan.swift
    ../../public/core/Span/RawSpan.swift
    ../../public/core/Span/Span.swift

@@ -17,6 +19,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin" AND DEFINED SWIFT_STDLIB_LIBRARY_BUILD_TY
      -module-abi-name Swift
      -DSPAN_COMPATIBILITY_STUB

+    NO_SWIFTMODULE
+
    DEPLOYMENT_VERSION_OSX ${COMPATIBILITY_MINIMUM_DEPLOYMENT_VERSION_OSX}
    DEPLOYMENT_VERSION_IOS ${COMPATIBILITY_MINIMUM_DEPLOYMENT_VERSION_IOS}
    DEPLOYMENT_VERSION_TVOS ${COMPATIBILITY_MINIMUM_DEPLOYMENT_VERSION_TVOS}
--- a/stdlib/toolchain/CompatibilitySpan/FakeStdlib.swift
+++ b/stdlib/toolchain/CompatibilitySpan/FakeStdlib.swift
@@ -59,6 +59,20 @@ internal func _overrideLifetime<
  dependent
 }

+@unsafe
+@_unsafeNonescapableResult
+@_alwaysEmitIntoClient
+@_transparent
+@lifetime(&source)
+internal func _overrideLifetime<
+  T: ~Copyable & ~Escapable, U: ~Copyable & ~Escapable
+>(
+  _ dependent: consuming T,
+  mutating source: inout U
+) -> T {
+  dependent
+}
+
 extension Range {
    @_alwaysEmitIntoClient
 	internal init(_uncheckedBounds bounds: (lower: Bound, upper: Bound)) {
--- a/test/abi/macOS/arm64/stdlib.swift
+++ b/test/abi/macOS/arm64/stdlib.swift
@@ -1093,3 +1093,36 @@ Added: _$ss18EnumeratedSequenceVyxGSKsSkRzrlMc

 // Indirect tagged string creation
 Added: __swift_stdlib_CreateIndirectTaggedPointerString
+
+// Span backward deployment
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE10_uncheckedAByxGSryxG_tcfC$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE8_pointerSvSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanV6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanV8_pointerSvSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVN$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE5countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE6_countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE7indicesSnySiGvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE7isEmptySbvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE8_pointerSVSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE8_pointerSVSgvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVss15BitwiseCopyableRzlE9uncheckedxSi_tcipMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVss15BitwiseCopyableRzlEyxSicipMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV11byteOffsetsSnySiGvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV6_countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV7isEmptySbvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV8_pointerSVSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV8_pointerSVSgvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV9byteCountSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVN$
--- a/test/abi/macOS/x86_64/stdlib.swift
+++ b/test/abi/macOS/x86_64/stdlib.swift
@@ -1093,3 +1093,38 @@ Added: _$ss18EnumeratedSequenceVyxGSKsSkRzrlMc

 // Indirect tagged string creation
 Added: __swift_stdlib_CreateIndirectTaggedPointerString
+
+
+// Span backward deployment
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE10_uncheckedAByxGSryxG_tcfC$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss11MutableSpanVsRi_zrlE8_pointerSvSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanV6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanV8_pointerSvSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss14MutableRawSpanVN$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE5countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE6_countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE7indicesSnySiGvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE7isEmptySbvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE8_pointerSVSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVsRi_zrlE8_pointerSVSgvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVss15BitwiseCopyableRzlE9uncheckedxSi_tcipMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss4SpanVss15BitwiseCopyableRzlEyxSicipMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV11byteOffsetsSnySiGvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV6_countSivg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV6_countSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV7isEmptySbvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV8_pointerSVSgvg$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV8_pointerSVSgvpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanV9byteCountSivpMV$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVMa$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVMn$
+Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7RawSpanVN$
+
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -502,7 +502,7 @@ def availability_macro_to_swift_abi_target_triple(macro):
    # Use a regex and split to pull out the components of an availability macro
    # that is formatted like this:
    #    SwiftStdlib 5.0:macOS 10.14.4, iOS 12.2, watchOS 5.2, tvOS 12.2
-    matches = re.search(r'^[\s]*SwiftStdlib[\s]+([0-9\.]+)[\s]*:[\s]*(.+)', macro)
+    matches = re.search(r'^[\s]*Swift(?:Stdlib|CompatibilitySpan)[\s]+([0-9\.]+)[\s]*:[\s]*(.+)', macro)
    stdlib_vers = matches.group(1)
    vers_by_platform = {}
    for platform_vers in matches.group(2).split(', '):
--- a/utils/availability-macros.def
+++ b/utils/availability-macros.def
@@ -36,8 +36,16 @@ SwiftStdlib 5.8:macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4
 SwiftStdlib 5.9:macOS 14.0, iOS 17.0, watchOS 10.0, tvOS 17.0
 SwiftStdlib 5.10:macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4, visionOS 1.1
 SwiftStdlib 6.0:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0
-SwiftStdlib 6.1:macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999
+SwiftStdlib 6.1:macOS 15.4, iOS 18.4, watchOS 11.4, tvOS 18.4, visionOS 2.4
 SwiftStdlib 6.2:macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999
+
+# Like SwiftStdlib 5.0, but also the oldest visionOS from SwiftStdlib 5.10.
+SwiftCompatibilitySpan 5.0:macOS 10.14.4, iOS 12.2, watchOS 5.2, tvOS 12.2, visionOS 1.1
+
+# Note: This cannot be 9999, so use the last non-placeholder entry instead.
+# This will go away once 'SwiftStdlib 6.2' is filled in.
+SwiftCompatibilitySpan 6.2:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0
+
 # TODO: When you add a new version, remember to tell the compiler about it
 # by also adding it to include/swift/AST/RuntimeVersions.def.

--- a/validation-test/ParseableInterface/verify_all_overlays.py
+++ b/validation-test/ParseableInterface/verify_all_overlays.py
@@ -48,6 +48,7 @@ for filename in os.listdir(sdk_overlay_dir):
        "SwiftLang",
        # swiftCxxStdlib uses `-module-interface-preserve-types-as-written`
        "CxxStdlib",
+        "CompatibilitySpan",
    ]:
        continue