Fix the GENERATE_PACKAGE_SUBFOLDERS option for Qml modules

Add the missing include directory to workaround QTBUG-115499.
Make sure that '$<TARGET_PROPERTY' genex is evaluated for
_protobuf_registration targets.

TODO: Extra include directories should be removed since they might
lead to ambiguous include records if .proto files contain messages
with same name but in different protobuf packages.

Fixes: QTBUG-114077
Task-number: QTBUG-115499
Pick-to: 6.6
Change-Id: Ifb9002435b20034967f202a5dc94ec51a3704f64
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Konrad Kujawa <konrad.kujawa@qt.io>

src/tools/qtprotobufgen/Qt6ProtobufToolsMacros.cmake

@@ -275,6 +275,7 @@ function(qt6_add_protobuf target)
         set(output_directory "${arg_OUTPUT_DIRECTORY}")
     endif()
 
+    set(extra_include_directories "")
     set(cpp_sources "")
     set(idx 0)
     foreach(f IN LISTS proto_files)
@@ -286,6 +287,8 @@ function(qt6_add_protobuf target)
             endif()
             string(REPLACE "." "/" package_full_path "${package}/")
             math(EXPR idx "${idx} + 1")
+            list(APPEND extra_include_directories
+                "$<BUILD_INTERFACE:${output_directory}/${package_full_path}>")
         else()
             set(package_full_path "")
         endif()
@@ -384,6 +387,10 @@ function(qt6_add_protobuf target)
             PRIVATE "/Zc:__cplusplus" "/permissive-" "/bigobj")
     endif()
 
+    # TODO: adding these include paths might cause the ambiguous include handling if
+    # two different packages contain messages with the same name. This should be fixed
+    # in moc and qmltypesregistar, see QTBUG-115499.
+    target_include_directories(${target} PRIVATE ${extra_include_directories})
     target_link_libraries(${target} PRIVATE
         ${QT_CMAKE_EXPORT_NAMESPACE}::Protobuf
     )
@@ -398,7 +405,7 @@ function(qt6_add_protobuf target)
             add_dependencies(${target} ${target}_protobuf_registration)
 
             target_include_directories(${target}_protobuf_registration
-                PRIVATE "$<TARGET_PROPERTY:${target},INCLUDE_DIRECTORIES>")
+                PRIVATE "$<GENEX_EVAL:$<TARGET_PROPERTY:${target},INCLUDE_DIRECTORIES>>")
             target_link_libraries(${target}_protobuf_registration
                 PRIVATE
                     ${QT_CMAKE_EXPORT_NAMESPACE}::Platform

tests/auto/protobufqml/basic/CMakeLists.txt

@@ -19,6 +19,7 @@ qt_add_protobuf(tst_protobuf_basictypes_qml_gen
     PROTO_FILES
         ../../shared/data/proto/basicmessages.proto
     QML
+    GENERATE_PACKAGE_SUBFOLDERS
     FIELD_ENUM
     OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/qt_protobuf_generated"
 )