1 files changed, 30 insertions, 2 deletions
diff --git a/cmake/QtPlatformTargetHelpers.cmake b/cmake/QtPlatformTargetHelpers.cmake
index b98894829f..9c95c0883f 100644
--- a/cmake/QtPlatformTargetHelpers.cmake
+++ b/cmake/QtPlatformTargetHelpers.cmake
@@ -1,15 +1,20 @@
 # Defines the public Qt::Platform target, which serves as a dependency for all internal Qt target
 # as well as user projects consuming Qt.
 function(qt_internal_setup_public_platform_target)
+    qt_internal_get_platform_definition_include_dir(
+        install_interface_definition_dir
+        build_interface_definition_dir
+    )
+
     ## QtPlatform Target:
     add_library(Platform INTERFACE)
     add_library(Qt::Platform ALIAS Platform)
     add_library(${INSTALL_CMAKE_NAMESPACE}::Platform ALIAS Platform)
     target_include_directories(Platform
         INTERFACE
-        $<BUILD_INTERFACE:${QT_PLATFORM_DEFINITION_BUILD_INTERFACE_DIR}>
+        $<BUILD_INTERFACE:${build_interface_definition_dir}>
         $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
-        $<INSTALL_INTERFACE:${QT_PLATFORM_DEFINITION_DIR}>
+        $<INSTALL_INTERFACE:${install_interface_definition_dir}>
         $<INSTALL_INTERFACE:${INSTALL_INCLUDEDIR}>
         )
     target_compile_definitions(Platform INTERFACE ${QT_PLATFORM_DEFINITIONS})
@@ -33,3 +38,26 @@ function(qt_internal_setup_public_platform_target)
     # By default enable unicode on WIN32 platforms for both Qt and Qt consumers. Can be opted out.
     qt_internal_enable_unicode_defines(Platform)
 endfunction()
+
+function(qt_internal_get_platform_definition_include_dir install_interface build_interface)
+    # Used by consumers of prefix builds via INSTALL_INTERFACE (relative path).
+    set(${install_interface} "${INSTALL_MKSPECSDIR}/${QT_QMAKE_TARGET_MKSPEC}" PARENT_SCOPE)
+
+    # Used by qtbase in prefix builds via BUILD_INTERFACE
+    set(build_interface_base_dir
+        "${CMAKE_CURRENT_LIST_DIR}/../mkspecs"
+    )
+
+    # Used by qtbase and consumers in non-prefix builds via BUILD_INTERFACE
+    if(NOT QT_WILL_INSTALL)
+        set(build_interface_base_dir
+            "${QT_BUILD_DIR}/${INSTALL_MKSPECSDIR}"
+        )
+    endif()
+
+    get_filename_component(build_interface_dir
+        "${build_interface_base_dir}/${QT_QMAKE_TARGET_MKSPEC}"
+        ABSOLUTE
+    )
+    set(${build_interface} "${build_interface_dir}" PARENT_SCOPE)
+endfunction()