CMake: Clean up logic to prepare building pure QML modules

Make sure we don't create bogus typeinfo entries, do create a target if
there are no C++ files, and do install created targets.

This way we do build the qmlcachegen-created files and link them into a
library which is subsequently deployed. It's not a real plugin, though,
and we need to specially handle this in QML. That's material for a
separate change.

Change-Id: I516d4611b6041a23489ce57df38dd83114dcc5de
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

2 files changed, 28 insertions, 9 deletions

diff --git a/src/qml/Qt6QmlBuildInternals.cmake b/src/qml/Qt6QmlBuildInternals.cmake
index c2018d71f8..a9b20235ad 100644
--- a/src/qml/Qt6QmlBuildInternals.cmake
+++ b/src/qml/Qt6QmlBuildInternals.cmake
@@ -91,7 +91,7 @@ function(qt_internal_add_qml_module target)
     endif()
 
 
-    if (arg_CPP_PLUGIN)
+    if (arg_CPP_PLUGIN OR arg_SOURCES)
         set(no_create_option DO_NOT_CREATE_TARGET)
     endif()
 
@@ -121,6 +121,16 @@ function(qt_internal_add_qml_module target)
 
     qt_path_join(qml_module_install_dir ${QT_INSTALL_DIR} "${INSTALL_QMLDIR}/${arg_TARGET_PATH}")
 
+    set(qml_module_build_dir "")
+    if(NOT QT_WILL_INSTALL)
+        qt_path_join(qml_module_build_dir ${QT_INSTALL_DIR} "${INSTALL_QMLDIR}/${arg_TARGET_PATH}")
+        set(qml_module_build_dir OUTPUT_DIRECTORY "${qml_module_build_dir}")
+    endif()
+
+    if (arg_SOURCES AND NOT arg_TYPEINFO)
+        set(arg_TYPEINFO "plugins.qmltypes")
+    endif()
+
     qt6_add_qml_module(${target}
         ${designer_supported_arg}
         ${no_create_option}
@@ -138,8 +148,8 @@ function(qt_internal_add_qml_module target)
         OPTIONAL_IMPORTS "${arg_OPTIONAL_IMPORTS}"
         TYPEINFO "${arg_TYPEINFO}"
         DO_NOT_INSTALL_METADATA
-        DO_NOT_CREATE_TARGET
         INSTALL_QML_FILES
+        ${qml_module_build_dir}
         INSTALL_LOCATION "${qml_module_install_dir}"
         DEPENDENCIES ${arg_DEPENDENCIES}
         RESOURCE_EXPORT "${INSTALL_CMAKE_NAMESPACE}${target}Targets"
diff --git a/src/qml/Qt6QmlMacros.cmake b/src/qml/Qt6QmlMacros.cmake
index b4acf4076d..c6b11d5ba1 100644
--- a/src/qml/Qt6QmlMacros.cmake
+++ b/src/qml/Qt6QmlMacros.cmake
@@ -225,13 +225,20 @@ function(qt6_add_qml_module target)
             QT_QML_MODULE_RESOURCE_EXPORT "${arg_RESOURCE_EXPORT}"
     )
 
-    if (arg_OUTPUT_DIRECTORY AND NOT DO_NOT_CREATE_TARGET)
-        set_target_properties(${target}
-            PROPERTIES
-                LIBRARY_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
-                ARCHIVE_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
-         )
+    if (NOT DO_NOT_CREATE_TARGET)
+        if (arg_OUTPUT_DIRECTORY)
+            set_target_properties(${target}
+                PROPERTIES
+                    LIBRARY_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
+                    ARCHIVE_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
+            )
+        elseif (should_install)
+            install(TARGETS ${target}
+                DESTINATION "${arg_INSTALL_LOCATION}"
+            )
+        endif()
     endif()
+
     if (arg_OUTPUT_DIRECTORY)
         set(target_output_dir ${arg_OUTPUT_DIRECTORY})
     else()
@@ -281,13 +288,15 @@ function(qt6_add_qml_module target)
     endif()
     if (arg_TYPEINFO)
         string(APPEND qmldir_file_contents "typeinfo ${arg_TYPEINFO}\n")
-    else()
+    elseif (arg_SOURCES)
         # This always need to be written out since at the moment we have cases
         # where qmltyperegistrar is not run with the plugin but on a module
         # e.g: src/qml generates the qmltypes for src/imports/qtqml.
         # When this has been fixed/standardized we should move this to
         # qt6_qml_type_registration() so that it is written out when the
         # plugins.qmltypes is actually generated.
+        # However, if there are no sources, then this is a pure QML module. In
+        # that case there cannot be a plugins.qmltypes file.
         string(APPEND qmldir_file_contents "typeinfo plugins.qmltypes\n")
     endif()