CMake: Warn when the qt6_add_qml_module INSTALL_PATH is missing

If a user uses the public API function to create a qml module, they
should also provide the installation path for the qml files, the
compiled plugin (if C++ is involved), and the other accompanying files
like qmldir.

The user can specify the installation path via the INSTALL_PATH option
to qt6_add_qml_module.

Warn the user when they haven't done so.

Also because we can't really guess where to install (we don't want to
install into the Qt qml install prefix and pollute the content there),
make sure to not install the files somewhere randomly.

Task-number: QTBUG-84403
Change-Id: I1d8e9035b07952347f5edf854bf39869d128df4e
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 30 insertions, 19 deletions

diff --git a/src/qml/Qt6QmlMacros.cmake b/src/qml/Qt6QmlMacros.cmake
index 6cb5534053..fba43be215 100644
--- a/src/qml/Qt6QmlMacros.cmake
+++ b/src/qml/Qt6QmlMacros.cmake
@@ -156,29 +156,33 @@ function(qt6_add_qml_module target)
         set(arg_RESOURCE_PREFIX "/org.qt-project/imports")
     endif()
 
+    set(should_install "TRUE")
     if (NOT arg_INSTALL_LOCATION)
-        set(arg_INSTALL_LOCATION "${INSTALL_QMLDIR}/${arg_TARGET_PATH}")
+        message(AUTHOR_WARNING "No Qml install location provided for target ${target}."
+                               "Consider specifying the INSTALL_LOCATION option.")
+        set(should_install "FALSE")
     endif()
+
     if (DEFINED QT_WILL_INSTALL AND NOT QT_WILL_INSTALL
-            AND NOT IS_ABSOLUTE "${arg_INSTALL_LOCATION}")
+            AND NOT IS_ABSOLUTE "${arg_INSTALL_LOCATION}" AND QT_BUILD_DIR)
         set(arg_INSTALL_LOCATION "${QT_BUILD_DIR}/${arg_INSTALL_LOCATION}")
     endif()
 
     set_target_properties(${target}
         PROPERTIES
-            QT_QML_MODULE_TARGET_PATH ${arg_TARGET_PATH}
-            QT_QML_MODULE_URI ${arg_URI}
-            QT_RESOURCE_PREFIX ${arg_RESOURCE_PREFIX}/${arg_TARGET_PATH}
-            QT_QML_MODULE_VERSION ${arg_VERSION}
-            QT_QML_MODULE_INSTALL_DIR ${arg_INSTALL_LOCATION}
+            QT_QML_MODULE_TARGET_PATH "${arg_TARGET_PATH}"
+            QT_QML_MODULE_URI "${arg_URI}"
+            QT_RESOURCE_PREFIX "${arg_RESOURCE_PREFIX}/${arg_TARGET_PATH}"
+            QT_QML_MODULE_VERSION "${arg_VERSION}"
+            QT_QML_MODULE_INSTALL_DIR "${arg_INSTALL_LOCATION}"
             QT_QML_MODULE_RESOURCE_EXPORT "${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 ${arg_OUTPUT_DIRECTORY}
+                LIBRARY_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
+                ARCHIVE_OUTPUT_DIRECTORY "${arg_OUTPUT_DIRECTORY}"
          )
     endif()
     if (arg_OUTPUT_DIRECTORY)
@@ -273,7 +277,7 @@ function(qt6_add_qml_module target)
         if (resource_targets AND arg_RESOURCE_EXPORT)
             install(TARGETS ${resource_targets}
                 EXPORT "${arg_RESOURCE_EXPORT}"
-                DESTINATION ${arg_INSTALL_LOCATION}
+                DESTINATION "${arg_INSTALL_LOCATION}"
             )
         endif()
     else()
@@ -285,9 +289,9 @@ function(qt6_add_qml_module target)
         )
 
         # Install QMLDIR file
-        if (NOT DO_NOT_INSTALL_METADATA)
+        if (NOT DO_NOT_INSTALL_METADATA AND should_install)
             install(FILES ${qmldir_file}
-                DESTINATION ${arg_INSTALL_LOCATION}
+                DESTINATION "${arg_INSTALL_LOCATION}"
             )
         endif()
     endif()
@@ -299,9 +303,9 @@ function(qt6_add_qml_module target)
             PROPERTIES QT_QML_MODULE_PLUGIN_TYPES_FILE "${target_plugin_qmltypes}"
         )
         file(APPEND ${qmldir_file} "typeinfo plugins.qmltypes\n")
-        if (NOT arg_DO_NOT_INSTALL_METADATA)
-            install(FILES ${target_plugin_qmltypes}
-                DESTINATION ${arg_INSTALL_LOCATION}
+        if (NOT arg_DO_NOT_INSTALL_METADATA AND should_install)
+            install(FILES "${target_plugin_qmltypes}"
+                    DESTINATION "${arg_INSTALL_LOCATION}"
             )
         endif()
 
@@ -314,9 +318,9 @@ function(qt6_add_qml_module target)
 
     # Copy/Install type info file
     if (EXISTS ${arg_TYPEINFO})
-        if (NOT arg_DO_NOT_INSTALL_METADATA)
-            install(FILES ${arg_TYPEINFO}
-                DESTINATION ${arg_INSTALL_LOCATION}
+        if (NOT arg_DO_NOT_INSTALL_METADATA AND should_install)
+            install(FILES "${arg_TYPEINFO}"
+                    DESTINATION "${arg_INSTALL_LOCATION}"
             )
         endif()
 
@@ -390,6 +394,13 @@ function(qt6_target_qml_files target)
     get_target_property(skip_type_registration ${target} QT_QML_MODULE_SKIP_TYPE_REGISTRATION)
     get_target_property(target_resource_export ${target} QT_QML_MODULE_RESOURCE_EXPORT)
     get_target_property(qml_module_install_dir ${target} QT_QML_MODULE_INSTALL_DIR)
+
+    if(NOT qml_module_install_dir)
+        message(AUTHOR_WARNING
+            "No QT_QML_MODULE_INSTALL_DIR property value provided for the '${target}' target. "
+            "Installation of qml_files will most likely be broken.")
+    endif()
+
     if (resource_targets)
         install(TARGETS ${resource_targets}
             EXPORT "${target_resource_export}"
@@ -399,7 +410,7 @@ function(qt6_target_qml_files target)
 
     set(file_contents "")
     foreach(qml_file IN LISTS arg_FILES)
-        if (install_qml_files)
+        if (install_qml_files AND qml_module_install_dir)
             if (NOT QT_WILL_INSTALL)
                 file(COPY "${qml_file}" DESTINATION "${qml_module_install_dir}")
             else()