[cmake] add FindSwiftPlatformOverlay.cmake (#82895)

Add FindSwiftPlatformOverlay module responsible for finding the platform
overlays for the supplemental libraries

Author: justice-adams-apple

Runtimes/Supplemental/cmake/modules/FindSwiftOverlay.cmake

@@ -0,0 +1,196 @@
+#[=======================================================================[.rst:
+FindSwiftOverlay
+------------
+
+Find SwiftOverlay, deferring to the associated SwiftOverlayConfig.cmake when requested.
+This is meant to find the platform overlays to be linked by the Supplemental libraries.
+
+Imported Targets
+^^^^^^^^^^^^^^^^
+
+The following :prop_tgt:`IMPORTED` TARGETS may be defined:
+
+ ``SwiftOverlay``
+
+Hint Variables
+^^^^^^^^^^^^^^
+
+ ``SDKROOT`` (environment variable)
+   Set the path to the Swift SDK Root.
+   This only affects Windows and Android builds.
+
+ ``Swift_SDKROOT``
+   Set the path to the Swift SDK installation.
+   This affects Linux, Android, and Windows builds.
+   Apple builds always use the overlay provided by the SDK.
+
+#]=======================================================================]
+
+include_guard(GLOBAL)
+
+# This was loosely modelled after other find modules
+# (namely FindGLEW), where the equivalent parameter
+# is not stored in cache (possibly because we want
+# the project importing it to be able to
+# it "immediately")
+if(NOT DEFINED SwiftOverlay_USE_STATIC_LIBS)
+  set(SwiftOverlay_USE_STATIC_LIBS OFF)
+  if(NOT BUILD_SHARED_LIBS AND NOT APPLE)
+    set(SwiftOverlay_USE_STATIC_LIBS ON)
+  endif()
+endif()
+
+if(SwiftOverlay_DIR)
+  if(${CMAKE_FIND_PACKAGE_NAME}_FIND_REQUIRED)
+    list(APPEND args REQUIRED)
+  endif()
+  if(${CMAKE_FIND_PACKAGE_NAME}_FIND_QUIETLY)
+    list(APPEND args QUIET)
+  endif()
+  find_package(SwiftOverlay CONFIG ${args})
+  return()
+endif()
+
+include(FindPackageHandleStandardArgs)
+include(PlatformInfo)
+
+if(APPLE)
+  list(APPEND OVERLAY_TARGET_NAMES "swiftDarwin")
+  # Look in the SDK
+  list(APPEND swiftDarwin_INCLUDE_DIR_HINTS
+    "${CMAKE_OSX_SYSROOT}/usr/lib/swift")
+  list(APPEND swiftDarwin_LIBRARY_HINTS
+    "${CMAKE_OSX_SYSROOT}/usr/lib/swift")
+  # When building for Apple platforms, swiftDarwin always comes from within the
+  # SDK as a tbd for a shared library in the shared cache.
+  list(APPEND swiftDarwin_NAMES libswiftDarwin.tbd)
+  set(swiftDarwin_MODULE_NAME "Darwin.swiftmodule")
+elseif(LINUX)
+  #ToDo(swiftlang/swift/issues/83014): Handle the static MUSL SDK case
+  list(APPEND OVERLAY_TARGET_NAMES "swiftGlibc")
+
+  # Look in the SDK
+  if (SwiftOverlay_USE_STATIC_LIBS)
+    list(APPEND swiftGlibc_INCLUDE_DIR_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift_static/linux")
+    list(APPEND swiftGlibc_LIBRARY_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift_static/linux")
+    list(APPEND swiftGlibc_NAMES libswiftGlibc.a)
+  else()
+    list(APPEND swiftGlibc_INCLUDE_DIR_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift/linux/")
+    list(APPEND swiftGlibc_LIBRARY_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift/linux")
+    list(APPEND swiftGlibc_NAMES libswiftGlibc.so)
+  endif()
+  set(swiftGlibc_MODULE_NAME "Glibc.swiftmodule")
+elseif(WIN32)
+  list(APPEND OVERLAY_TARGET_NAMES "swiftWinSDK")
+  list(APPEND OVERLAY_TARGET_NAMES "swiftCRT")
+
+  list(APPEND swiftWinSDK_INCLUDE_DIR_HINTS
+    "${Swift_SDKROOT}/usr/lib/swift/windows"
+    "$ENV{SDKROOT}/usr/lib/swift/windows")
+  list(APPEND swiftWinSDK_LIBRARY_HINTS
+    "${Swift_SDKROOT}/usr/lib/swift/${${PROJECT_NAME}_PLATFORM_SUBDIR}/${${PROJECT_NAME}_ARCH_SUBDIR}"
+    "${Swift_SDKROOT}/usr/lib/swift"
+    "$ENV{SDKROOT}/usr/lib/swift/${${PROJECT_NAME}_PLATFORM_SUBDIR}/${${PROJECT_NAME}_ARCH_SUBDIR}"
+    "$ENV{SDKROOT}/usr/lib/swift")
+
+  if(SwiftOverlay_USE_STATIC_LIBS)
+    list(APPEND swiftWinSDK_NAMES libswiftWinSDK.lib)
+  else()
+    list(APPEND swiftWinSDK_NAMES swiftWinSDK.lib)
+  endif()
+  list(APPEND swiftWinSDK_MODULE_NAME "WinSDK.swiftmodule")
+
+  list(APPEND swiftCRT_INCLUDE_DIR_HINTS
+    "${Swift_SDKROOT}/usr/lib/swift/windows"
+    "$ENV{SDKROOT}/usr/lib/swift/windows")
+  list(APPEND swiftCRT_LIBRARY_HINTS
+    "${Swift_SDKROOT}/usr/lib/swift/${${PROJECT_NAME}_PLATFORM_SUBDIR}/${${PROJECT_NAME}_ARCH_SUBDIR}"
+    "${Swift_SDKROOT}/usr/lib/swift"
+    "$ENV{SDKROOT}/usr/lib/swift/${${PROJECT_NAME}_PLATFORM_SUBDIR}/${${PROJECT_NAME}_ARCH_SUBDIR}"
+    "$ENV{SDKROOT}/usr/lib/swift")
+
+ if(SwiftOverlay_USE_STATIC_LIBS)
+    list(APPEND swiftCRT_NAMES libswiftCRT.lib)
+  else()
+    list(APPEND swiftCRT_NAMES swiftCRT.lib)
+  endif()
+  set(swiftCRT_MODULE_NAME "CRT.swiftmodule")
+elseif(ANDROID)
+  list(APPEND OVERLAY_TARGET_NAMES "swiftAndroid")
+
+  if (SwiftOverlay_USE_STATIC_LIBS)
+    list(APPEND swiftAndroid_INCLUDE_DIR_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift_static/android"
+      "$ENV{SDKROOT}/usr/lib/swift_static/android")
+    list(APPEND swiftAndroid_LIBRARY_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift_static/android/${${PROJECT_NAME}_ARCH_SUBDIR}"
+      "${Swift_SDKROOT}/usr/lib/swift_static"
+      "$ENV{SDKROOT}/usr/lib/swift_static/android/${${PROJECT_NAME}_ARCH_SUBDIR}"
+      "$ENV{SDKROOT}/usr/lib/swift_static")
+    list(APPEND swiftAndroid_NAMES libswiftAndroid.a)
+  else()
+    list(APPEND swiftAndroid_INCLUDE_DIR_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift/android"
+      "$ENV{SDKROOT}/usr/lib/swift/android")
+    list(APPEND swiftAndroid_LIBRARY_HINTS
+      "${Swift_SDKROOT}/usr/lib/swift/android/${${PROJECT_NAME}_ARCH_SUBDIR}"
+      "${Swift_SDKROOT}/usr/lib/swift"
+      "$ENV{SDKROOT}/usr/lib/swift/android/${${PROJECT_NAME}_ARCH_SUBDIR}"
+      "$ENV{SDKROOT}/usr/lib/swift")
+    list(APPEND swiftAndroid_NAMES libswiftAndroid.so)
+  endif()
+  set(swiftAndroid_MODULE_NAME "Android.swiftmodule")
+else()
+  message(FATAL_ERROR "FindSwiftOverlay.cmake module search not implemented for targeted platform\n"
+  " Build the Overlays for your platform and set the appropriate `SwiftOverlay_DIR` variable to"
+  " the directory containing SwiftOverlayConfig.cmake\n")
+endif()
+
+# Setup SwiftOverlay interface library and link it against the explicit
+# overlay targets
+add_library(SwiftOverlay INTERFACE)
+
+foreach(OVERLAY_TARGET ${OVERLAY_TARGET_NAMES})
+  find_path(${OVERLAY_TARGET}_INCLUDE_DIR
+    ${${OVERLAY_TARGET}_MODULE_NAME}
+    NO_CMAKE_FIND_ROOT_PATH
+    HINTS
+      ${${OVERLAY_TARGET}_INCLUDE_DIR_HINTS})
+  find_library(${OVERLAY_TARGET}_LIBRARY
+    NAMES
+      ${${OVERLAY_TARGET}_NAMES}
+    NO_CMAKE_FIND_ROOT_PATH
+    HINTS
+      ${${OVERLAY_TARGET}_LIBRARY_HINTS})
+
+  if(SwiftOverlay_USE_STATIC_LIBS)
+    add_library(${OVERLAY_TARGET} STATIC IMPORTED GLOBAL)
+  else()
+    add_library(${OVERLAY_TARGET} SHARED IMPORTED GLOBAL)
+  endif()
+
+  target_include_directories(${OVERLAY_TARGET} INTERFACE
+    "${${OVERLAY_TARGET}_INCLUDE_DIR}")
+
+  if(LINUX OR ANDROID)
+    set_target_properties(${OVERLAY_TARGET} PROPERTIES
+      IMPORTED_LOCATION "${${OVERLAY_TARGET}_LIBRARY}")
+  else()
+    set_target_properties(${OVERLAY_TARGET} PROPERTIES
+      IMPORTED_IMPLIB "${${OVERLAY_TARGET}_LIBRARY}")
+  endif()
+
+  target_link_libraries(SwiftOverlay INTERFACE
+      ${OVERLAY_TARGET})
+endforeach()
+
+foreach(OVERLAY_TARGET ${OVERLAY_TARGET_NAMES})
+  list(APPEND vars_to_check "${OVERLAY_TARGET}_LIBRARY" "${OVERLAY_TARGET}_INCLUDE_DIR")
+endforeach()
+
+find_package_handle_standard_args(SwiftOverlay DEFAULT_MSG
+  ${vars_to_check})