generate_apple_*_selection_file: Save/restore PACKAGE_PREFIX_DIR

Issue: #25827

3 files changed, 60 insertions, 0 deletions

diff --git a/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir-stdout.txt b/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir-stdout.txt
new file mode 100644
index 0000000..8821dad
--- /dev/null
+++ b/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir-stdout.txt
@@ -0,0 +1,3 @@
+(-- )?Hello from platform switch
+(-- )?Hello from arch switch
+(-- )?Hello from pkg_a
diff --git a/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir.cmake b/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir.cmake
new file mode 100644
index 0000000..e472665
--- /dev/null
+++ b/Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir.cmake
@@ -0,0 +1,50 @@
+set(CMAKE_INSTALL_DATADIR share)
+set(SWITCH_DIR platform/cmake)
+
+include(CMakePackageConfigHelpers)
+
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/pkg_a-config.cmake.in [[
+@PACKAGE_INIT@
+include("@PACKAGE_SWITCH_DIR@/platform-switch.cmake")
+include("@PACKAGE_CMAKE_INSTALL_DATADIR@/pkg_a_included.cmake")
+]])
+configure_package_config_file(
+  ${CMAKE_CURRENT_BINARY_DIR}/pkg_a-config.cmake.in
+  ${CMAKE_CURRENT_BINARY_DIR}/install/pkg_a-config.cmake
+  INSTALL_DESTINATION .
+  PATH_VARS CMAKE_INSTALL_DATADIR SWITCH_DIR
+)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/install/${CMAKE_INSTALL_DATADIR}/pkg_a_included.cmake
+  [[message(STATUS "Hello from pkg_a")]]
+)
+
+# To expose re-using the same package prefix variable, we need to use a
+# different install prefix. This is really contrived and not representative of
+# what a package should do.
+generate_apple_platform_selection_file(
+  ${CMAKE_CURRENT_BINARY_DIR}/install/platform/cmake/platform-switch.cmake
+  INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX}/platform
+  INSTALL_DESTINATION cmake
+  MACOS_INCLUDE_FILE cmake/switch_included.cmake  # relative to install prefix
+)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/install/platform/cmake/switch_included.cmake
+[[
+message(STATUS "Hello from platform switch")
+include("${CMAKE_CURRENT_LIST_DIR}/../arch/cmake/arch-switch.cmake")
+]]
+)
+
+generate_apple_architecture_selection_file(
+  ${CMAKE_CURRENT_BINARY_DIR}/install/platform/arch/cmake/arch-switch.cmake
+  INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX}/platform/arch
+  INSTALL_DESTINATION cmake
+  UNIVERSAL_ARCHITECTURES i386 x86_64 arm64 $(ARCHS_STANDARD)
+  UNIVERSAL_INCLUDE_FILE cmake/switch_included.cmake  # relative to install prefix
+)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/install/platform/arch/cmake/switch_included.cmake
+  [[message(STATUS "Hello from arch switch")]]
+)
+
+find_package(pkg_a REQUIRED NO_DEFAULT_PATH
+  PATHS ${CMAKE_CURRENT_BINARY_DIR}/install
+)
diff --git a/Tests/RunCMake/CMakePackage/RunCMakeTest.cmake b/Tests/RunCMake/CMakePackage/RunCMakeTest.cmake
index 848c36d..3b4bef5 100644
--- a/Tests/RunCMake/CMakePackage/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CMakePackage/RunCMakeTest.cmake
@@ -75,6 +75,13 @@ if(APPLE AND CMAKE_C_COMPILER_ID STREQUAL "AppleClang")
     set(enable_visionos 1)
   endif()
 
+  string(REPLACE ";" "\\;" macos_archs_for_cmd "${macos_archs}")
+  run_cmake_with_options(ApplePlatformGenSubdir
+    "-DCMAKE_OSX_ARCHITECTURES=${macos_archs_for_cmd}"
+    ${maybe_CMAKE_BUILD_TYPE}
+  )
+  unset(macos_archs_for_cmd)
+
   # Place all export/import steps in a single install prefix.
   set(apple_install ${RunCMake_BINARY_DIR}/apple-install)
   file(REMOVE_RECURSE "${apple_install}")