Fix and streamline header inclusion

While trying to port qtgraphicaleffects, when trying to configure
the project with a non-prefix build, the configuration fails with
the following error:

CMake Error in src/effects/CMakeLists.txt:
  Imported target "Qt::Qml" includes non-existent path

 "../qt_cmake/qtdeclarative_built_developer/include"

This is because we incorrectly export public include directories
that point to an "/include" folder under the repo build dir, whereas
in a non-prefix build the syncqt "/include" folder is actually in the
qtbase build dir.

Fix this, by introducing a new variable called "foo_repo_include_dir"
which will point to the correct include directory regardles of prefix
or non-prefix build. This variable is set by qt_internal_module_info.

Fix all relevant places to use this new variable. Also streamline
and remove any unncessary include directories in all our functions,
thus making everything consistent and hopefully easier to understand.

Change-Id: Icbe884701275c7754daecadcdba18048b4d779d0
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 67 insertions, 35 deletions

diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index b4d8403de3..724c7de4dd 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -746,7 +746,12 @@ endfunction()
 #  * foo_versioned with the value "Qt6Core" (based on major Qt version)
 #  * foo_upper with the value "CORE"
 #  * foo_lower with the value "core"
-#  * foo_include_dir with the module's include directory in the binary tree
+#  * foo_repo_include_dir with the module's include directory
+#    e.g for QtQuick it would be qtdeclarative_build_dir/include for a prefix build or
+#                                qtbase_build_dir/include for a non-prefix build
+#  * foo_include_dir with the module's include directory
+#    e.g for QtQuick it would be qtdeclarative_build_dir/include/QtQuick for a prefix build or
+#                                qtbase_build_dir/include/QtQuick for a non-prefix build
 #  * foo_define same as foo_uper but with - replaced as _
 function(qt_internal_module_info result target)
     set(module "Qt${target}")
@@ -757,6 +762,7 @@ function(qt_internal_module_info result target)
     string(REPLACE "-" "_" define "${upper}")
     set("${result}_upper" "${upper}" PARENT_SCOPE)
     set("${result}_lower" "${lower}" PARENT_SCOPE)
+    set("${result}_repo_include_dir" "${QT_BUILD_DIR}/include" PARENT_SCOPE)
     set("${result}_include_dir" "${QT_BUILD_DIR}/include/${module}" PARENT_SCOPE)
     set("${result}_define" "${define}" PARENT_SCOPE)
 endfunction()
@@ -1222,26 +1228,32 @@ function(add_qt_module target)
 
     qt_autogen_tools_initial_setup(${target})
 
-    set(_public_includes
-        $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
-        $<BUILD_INTERFACE:${module_include_dir}>
+    set(private_includes
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+        "${CMAKE_CURRENT_BINARY_DIR}"
+        "${module_include_dir}/${PROJECT_VERSION}"
+        "${module_include_dir}/${PROJECT_VERSION}/${module}"
+         ${arg_INCLUDE_DIRECTORIES}
     )
+
+    set(public_includes
+        # For the syncqt headers
+        "$<BUILD_INTERFACE:${module_repo_include_dir}>"
+        "$<BUILD_INTERFACE:${module_include_dir}>"
+    )
+
     if(NOT arg_NO_MODULE_HEADERS)
-        list(APPEND _public_includes $<INSTALL_INTERFACE:include/${module}>)
+        # For the syncqt headers
+        list(APPEND public_includes "$<INSTALL_INTERFACE:include/${module}>")
     endif()
-    list(APPEND _public_includes ${arg_PUBLIC_INCLUDE_DIRECTORIES})
+    list(APPEND public_includes ${arg_PUBLIC_INCLUDE_DIRECTORIES})
 
     extend_target("${target}"
         SOURCES ${arg_SOURCES}
-        PUBLIC_INCLUDE_DIRECTORIES
-            ${_public_includes}
         INCLUDE_DIRECTORIES
-            "${CMAKE_CURRENT_SOURCE_DIR}"
-            "${CMAKE_CURRENT_BINARY_DIR}"
-            $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
-            "${module_include_dir}/${PROJECT_VERSION}"
-            "${module_include_dir}/${PROJECT_VERSION}/${module}"
-            ${arg_INCLUDE_DIRECTORIES}
+            ${private_includes}
+        PUBLIC_INCLUDE_DIRECTORIES
+            ${public_includes}
         PUBLIC_DEFINES
             ${arg_PUBLIC_DEFINES}
             QT_${module_define}_LIB
@@ -1407,19 +1419,23 @@ set(QT_CMAKE_EXPORT_NAMESPACE ${QT_CMAKE_EXPORT_NAMESPACE})")
     # that belong to Qt.
     qt_internal_add_link_flags_no_undefined("${target}")
 
-    target_include_directories("${target_private}" INTERFACE
-        $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
-        $<BUILD_INTERFACE:${module_include_dir}/${PROJECT_VERSION}>
-        $<BUILD_INTERFACE:${module_include_dir}/${PROJECT_VERSION}/${module}>
+    set(interface_includes
+        "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>"
+        "$<BUILD_INTERFACE:${module_include_dir}/${PROJECT_VERSION}>"
+        "$<BUILD_INTERFACE:${module_include_dir}/${PROJECT_VERSION}/${module}>"
     )
 
     if(NOT arg_NO_MODULE_HEADERS)
-        target_include_directories("${target_private}" INTERFACE
-            $<INSTALL_INTERFACE:include/${module}/${PROJECT_VERSION}>
-            $<INSTALL_INTERFACE:include/${module}/${PROJECT_VERSION}/${module}>
+        list(APPEND interface_includes
+            "$<INSTALL_INTERFACE:include/${module}/${PROJECT_VERSION}>"
+            "$<INSTALL_INTERFACE:include/${module}/${PROJECT_VERSION}/${module}>"
         )
     endif()
 
+    target_include_directories("${target_private}" INTERFACE
+        ${interface_includes}
+    )
+
     if(NOT ${arg_DISABLE_TOOLS_EXPORT})
         qt_export_tools(${target})
     endif()
@@ -1616,15 +1632,24 @@ function(add_qt_plugin target)
     set_property(TARGET "${target}" PROPERTY QT_DEFAULT_PLUGIN "${_default_plugin}")
     set_property(TARGET "${target}" APPEND PROPERTY EXPORT_PROPERTIES "QT_PLUGIN_CLASS_NAME;QT_MODULE;QT_DEFAULT_PLUGIN")
 
+    set(private_includes
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+        "${CMAKE_CURRENT_BINARY_DIR}"
+         # For the syncqt headers
+        "$<BUILD_INTERFACE:${module_repo_include_dir}>"
+         ${arg_INCLUDE_DIRECTORIES}
+    )
+
+    set(public_includes
+        ${arg_PUBLIC_INCLUDE_DIRECTORIES}
+    )
+
     extend_target("${target}"
         SOURCES ${arg_SOURCES}
         INCLUDE_DIRECTORIES
-            "${CMAKE_CURRENT_SOURCE_DIR}"
-            "${CMAKE_CURRENT_BINARY_DIR}"
-            # For the syncqt headers
-            $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
-            ${arg_INCLUDE_DIRECTORIES}
-        PUBLIC_INCLUDE_DIRECTORIES ${arg_PUBLIC_INCLUDE_DIRECTORIES}
+            ${private_includes}
+        PUBLIC_INCLUDE_DIRECTORIES
+            ${public_includes}
         LIBRARIES ${arg_LIBRARIES} Qt::PlatformPluginInternal
         PUBLIC_LIBRARIES ${arg_PUBLIC_LIBRARIES}
         DEFINES
@@ -2179,12 +2204,15 @@ function(add_qt_executable name)
         set(extra_libraries "Qt::Core")
     endif()
 
+    set(private_includes
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+        "${CMAKE_CURRENT_BINARY_DIR}"
+         ${arg_INCLUDE_DIRECTORIES}
+    )
+
     extend_target("${name}"
         SOURCES ${arg_SOURCES}
-        INCLUDE_DIRECTORIES
-            "${CMAKE_CURRENT_SOURCE_DIR}"
-            "${CMAKE_CURRENT_BINARY_DIR}"
-            ${arg_INCLUDE_DIRECTORIES}
+        INCLUDE_DIRECTORIES ${private_includes}
         DEFINES ${arg_DEFINES}
         LIBRARIES ${arg_LIBRARIES}
         PUBLIC_LIBRARIES ${extra_libraries} ${arg_PUBLIC_LIBRARIES}
@@ -2231,6 +2259,13 @@ function(add_qt_test name)
         set(gui_text "GUI")
     endif()
 
+    set(private_includes
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+        "${CMAKE_CURRENT_BINARY_DIR}"
+        "$<BUILD_INTERFACE:${QT_BUILD_DIR}/include>"
+         ${arg_INCLUDE_DIRECTORIES}
+    )
+
     add_qt_executable("${name}"
         ${exceptions_text}
         ${gui_text}
@@ -2238,10 +2273,7 @@ function(add_qt_test name)
         OUTPUT_DIRECTORY "${path}"
         SOURCES "${arg_SOURCES}"
         INCLUDE_DIRECTORIES
-            "${CMAKE_CURRENT_SOURCE_DIR}"
-            "${CMAKE_CURRENT_BINARY_DIR}"
-            $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
-            ${arg_INCLUDE_DIRECTORIES}
+            ${private_includes}
         DEFINES
             QT_TESTCASE_BUILDDIR="${CMAKE_CURRENT_BINARY_DIR}"
             QT_TESTCASE_SOURCEDIR="${CMAKE_CURRENT_SOURCE_DIR}"