CMakePackageConfigHelpers: Use unique variable name for pkg prefix

Fixes: #25827

Modules/CMakePackageConfigHelpers.cmake

@@ -377,6 +377,24 @@ macro(WRITE_BASIC_PACKAGE_VERSION_FILE)
   write_basic_config_version_file(${ARGN})
 endmacro()
 
+function(__CMAKE_get_config_file_package_prefix outvar)
+  get_property(counter GLOBAL PROPERTY CMAKE_CONFIGURE_PACKAGE_CONFIG_FILE_COUNTER)
+  if(NOT counter)
+    set(counter 1)
+    set_property(GLOBAL PROPERTY CMAKE_CONFIGURE_PACKAGE_CONFIG_FILE_COUNTER ${counter})
+  endif()
+  set(${outvar} "PACKAGE_\${CMAKE_FIND_PACKAGE_NAME}_COUNTER_${counter}" PARENT_SCOPE)
+endfunction()
+
+function(__CMAKE_increment_config_file_counter)
+  get_property(counter GLOBAL PROPERTY CMAKE_CONFIGURE_PACKAGE_CONFIG_FILE_COUNTER)
+  if(NOT counter)
+    message(FATAL_ERROR "Internal error: global counter unexpectedly not set")
+  endif()
+  math(EXPR counter "${counter} + 1")
+  set_property(GLOBAL PROPERTY CMAKE_CONFIGURE_PACKAGE_CONFIG_FILE_COUNTER ${counter})
+endfunction()
+
 function(CONFIGURE_PACKAGE_CONFIG_FILE _inputFile _outputFile)
   set(options NO_SET_AND_CHECK_MACRO NO_CHECK_REQUIRED_COMPONENTS_MACRO)
   set(oneValueArgs INSTALL_DESTINATION INSTALL_PREFIX)
@@ -412,15 +430,17 @@ function(CONFIGURE_PACKAGE_CONFIG_FILE _inputFile _outputFile)
 
   file(RELATIVE_PATH PACKAGE_RELATIVE_PATH "${absInstallDir}" "${installPrefix}" )
 
+  __CMAKE_get_config_file_package_prefix(prefix_dir)
+
   foreach(var ${CCF_PATH_VARS})
     if(NOT DEFINED ${var})
       message(FATAL_ERROR "Variable ${var} does not exist")
     else()
       if(IS_ABSOLUTE "${${var}}")
-        string(REPLACE "${installPrefix}" "\${PACKAGE_PREFIX_DIR}"
+        string(REPLACE "${installPrefix}" "\${${prefix_dir}}"
                         PACKAGE_${var} "${${var}}")
       else()
-        set(PACKAGE_${var} "\${PACKAGE_PREFIX_DIR}/${${var}}")
+        set(PACKAGE_${var} "\${${prefix_dir}}/${${var}}")
       endif()
     endif()
   endforeach()
@@ -432,7 +452,7 @@ function(CONFIGURE_PACKAGE_CONFIG_FILE _inputFile _outputFile)
 ####### Any changes to this file will be overwritten by the next CMake run ####
 ####### The input file was ${inputFileName}                            ########
 
-get_filename_component(PACKAGE_PREFIX_DIR \"\${CMAKE_CURRENT_LIST_DIR}/${PACKAGE_RELATIVE_PATH}\" ABSOLUTE)
+get_filename_component(${prefix_dir} \"\${CMAKE_CURRENT_LIST_DIR}/${PACKAGE_RELATIVE_PATH}\" ABSOLUTE)
 ")
 
   if("${absInstallDir}" MATCHES "^(/usr)?/lib(64)?/.+")
@@ -443,7 +463,7 @@ get_filename_component(PACKAGE_PREFIX_DIR \"\${CMAKE_CURRENT_LIST_DIR}/${PACKAGE
 get_filename_component(_realCurr \"\${CMAKE_CURRENT_LIST_DIR}\" REALPATH)
 get_filename_component(_realOrig \"${absInstallDir}\" REALPATH)
 if(_realCurr STREQUAL _realOrig)
-  set(PACKAGE_PREFIX_DIR \"${installPrefix}\")
+  set(${prefix_dir} \"${installPrefix}\")
 endif()
 unset(_realOrig)
 unset(_realCurr)
@@ -481,6 +501,10 @@ endmacro()
 
   configure_file("${_inputFile}" "${_outputFile}" @ONLY)
 
+  # We're done writing the file. Make sure the next one has a unique prefix dir
+  # variable name (we may have multiple config files for the one package)
+  __CMAKE_increment_config_file_counter()
+
 endfunction()
 
 function(generate_apple_platform_selection_file _output_file)
@@ -521,12 +545,14 @@ function(generate_apple_platform_selection_file _output_file)
     set(_branch_INIT "")
   endif()
 
+  __CMAKE_get_config_file_package_prefix(prefix_dir)
+
   set(_else ELSE)
   foreach(_opt IN LISTS _config_file_options _else)
     if(_gpsf_${_opt})
       set(_config_file "${_gpsf_${_opt}}")
       if(NOT IS_ABSOLUTE "${_config_file}")
-        string(PREPEND _config_file [[${PACKAGE_PREFIX_DIR}/]])
+        string(PREPEND _config_file "\${${prefix_dir}}/")
       endif()
       set(_branch_${_opt} "include(\"${_config_file}\")")
     elseif(_gpsf_ERROR_VARIABLE)
@@ -600,11 +626,13 @@ function(generate_apple_architecture_selection_file _output_file)
     "endif()\n"
     )
 
+  __CMAKE_get_config_file_package_prefix(prefix_dir)
+
   foreach(pair IN ZIP_LISTS _gasf_SINGLE_ARCHITECTURES _gasf_SINGLE_ARCHITECTURE_INCLUDE_FILES)
     set(arch "${pair_0}")
     set(config_file "${pair_1}")
     if(NOT IS_ABSOLUTE "${config_file}")
-      string(PREPEND config_file [[${PACKAGE_PREFIX_DIR}/]])
+      string(PREPEND config_file "\${${prefix_dir}}/")
     endif()
     string(APPEND _branch_code
       "\n"
@@ -619,7 +647,7 @@ function(generate_apple_architecture_selection_file _output_file)
     string(JOIN " " universal_archs "${_gasf_UNIVERSAL_ARCHITECTURES}")
     set(config_file "${_gasf_UNIVERSAL_INCLUDE_FILE}")
     if(NOT IS_ABSOLUTE "${config_file}")
-      string(PREPEND config_file [[${PACKAGE_PREFIX_DIR}/]])
+      string(PREPEND config_file "\${${prefix_dir}}/")
     endif()
     string(APPEND _branch_code
       "\n"

Tests/RunCMake/CMakePackage/ApplePlatformGenSubdir-stdout.txt

@@ -0,0 +1,3 @@
+(-- )?Hello from platform switch
+(-- )?Hello from arch switch
+(-- )?Hello from pkg_a

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 but still with the same package name. 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
+)

Tests/RunCMake/CMakePackage/NestedConfigFile-stdout.txt

@@ -0,0 +1,2 @@
+(-- )?Hello from pkg_a
+(-- )?Hello from pkg_b

Tests/RunCMake/CMakePackage/NestedConfigFile.cmake

@@ -0,0 +1,39 @@
+set(CMAKE_INSTALL_DATADIR share)
+
+include(CMakePackageConfigHelpers)
+
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/pkg_a-config.cmake.in [[
+@PACKAGE_INIT@
+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/pkg_a-config.cmake
+  INSTALL_DESTINATION .
+  PATH_VARS CMAKE_INSTALL_DATADIR
+)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/install_pkg_a/share/pkg_a_included.cmake
+  [[message(STATUS "Hello from pkg_a")]]
+)
+
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/pkg_b-config.cmake.in [[
+@PACKAGE_INIT@
+include(CMakeFindDependencyMacro)
+find_dependency(pkg_a NO_DEFAULT_PATH
+    PATHS "@CMAKE_CURRENT_BINARY_DIR@/install_pkg_a"
+)
+include("@PACKAGE_CMAKE_INSTALL_DATADIR@/pkg_b_included.cmake")
+]])
+configure_package_config_file(
+  ${CMAKE_CURRENT_BINARY_DIR}/pkg_b-config.cmake.in
+  ${CMAKE_CURRENT_BINARY_DIR}/install_pkg_b/pkg_b-config.cmake
+  INSTALL_DESTINATION .
+  PATH_VARS CMAKE_INSTALL_DATADIR
+)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/install_pkg_b/share/pkg_b_included.cmake
+  [[message(STATUS "Hello from pkg_b")]]
+)
+
+find_package(pkg_b REQUIRED NO_DEFAULT_PATH
+  PATHS ${CMAKE_CURRENT_BINARY_DIR}/install_pkg_b
+)

Tests/RunCMake/CMakePackage/RunCMakeTest.cmake

@@ -4,6 +4,8 @@ if(NOT RunCMake_GENERATOR_IS_MULTI_CONFIG)
   set(maybe_CMAKE_BUILD_TYPE -DCMAKE_BUILD_TYPE=Release)
 endif()
 
+run_cmake_with_options(NestedConfigFile ${maybe_CMAKE_BUILD_TYPE})
+
 function(apple_export platform system_name archs sysroot)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/apple-export-${platform}-build)
   string(REPLACE ";" "\\;" archs "${archs}")
@@ -78,6 +80,12 @@ 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}"
+    ${maybe_CMAKE_BUILD_TYPE}
+  )
+
   apple_export(macos Darwin "${macos_archs}" macosx)
   apple_export(ios iOS "arm64" iphoneos)
   apple_export(tvos tvOS "arm64" appletvos)