App stoped working after `QTP0004 = NEW`

Dmitry.Sokolov

I've upgraded from v6.5 to v6.8. Then I've got CMake warnings regarding QTP0004, and switched it on as required:

if(QT_KNOWN_POLICY_QTP0004)
    qt_policy(SET QTP0004 NEW)
endif()

qt_add_qml_module(${PROJECT_NAME}
    URI         "myapp"
    QML_FILES   ${QML_FILES}
)

After that I have no any CMake warnings, but the app just stopped working (it exits without showing GUI). Logs:

...
qt.qml.import: addImplicitImport: qrc:/qt/qml/myapp/UI/MainWindow.qml
qt.qml.import: addFileImport: qrc:/qt/qml/myapp/UI/MainWindow.qml "." version "(latest)" as ""
qt.qml.import: importExtension: qrc:/qt/qml/myapp/UI/MainWindow.qml loaded ":/qt/qml/myapp/UI/qmldir"
qt.qml.diskcache: "qrc:/qt/qml/myapp/UI/MainWindow.qml: \"myapp\" is ambiguous. Found in qrc:/qt/qml/myapp/ and in qrc:/qt/qml/myapp/"
QQmlApplicationEngine failed to load component
qrc:/qt/qml/myapp/UI/MainWindow.qml: "myapp" is ambiguous. Found in qrc:/qt/qml/myapp/ and in qrc:/qt/qml/myapp/
The thread 'QQmlThread' (41572) has exited with code 0 (0x0).
qt.qml.gc.statistics: Qml GC memory allocation statistics:
qt.qml.gc.statistics: Total memory allocated: 0
...

The strange error: "myapp" is ambiguous. Found in qrc:/qt/qml/myapp/ and in qrc:/qt/qml/myapp/
What does it mean, and how to fix it?

Dmitry.Sokolov

Reverting to SET QTP0004 OLD fix the problem. But there is CMake warning...

FKosmale

Hi, it's a bit hard to tell what is causing the issue without more information. Could you describe how the files stored in ${QML_FILES} are structured? Do you have QML files which are part of your module and which explicitly import the module itself?

But generally, this sounds like a bug (in Qt itself) – if only to improve the warning message – and I'd be interested in a bug report.

Lastly, as a workaround to avoid warnings, you could also set the "NO_GENERATE_EXTRA_QMLDIRS" option instead of setting the policy to old (if the Qt version is high enough).