CMake: More fixes for QT_CMAKE_EXPORT_NAMESPACE not being available

The _qt_internal_write_qmldir_part function is
deferred to be called in the root CMAKE_BINARY_DIR, where
QT_CMAKE_EXPORT_NAMESPACE is not defined if find_package(Qt6) is not
called in the root of the project.

Make sure to pass the value of QT_CMAKE_EXPORT_NAMESPACE to the
function explicitly, from a scope where it is available.

This avoids errors like:
CMake Error at Qt6QmlMacros.cmake:155 (add_custom_command):
  Error evaluating generator expression:

    $<TARGET_FILE:::qmltyperegistrar>

  No target "::qmltyperegistrar"

As a drive by, do the same for _qt_internal_deferred_aotstats_setup
and use that variable, instead of the hardcoded Qt6:: prefix.

Add test.

Amends b47555feff
Amends f2889262c8

Pick-to: 6.8 6.9 6.10
Fixes: QTBUG-138559
Change-Id: I9ecf2149737f3522fa61b7188403c8470b5a15d3
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/qml/Qt6QmlMacros.cmake

@@ -96,7 +96,14 @@ function(_qt_internal_parse_qml_module_dependency dependency was_marked_as_targe
     endif()
 endfunction()
 
-function(_qt_internal_write_qmldir_part target)
+function(_qt_internal_write_qmldir_part target qt_cmake_export_namespace)
+    # _qt_internal_write_qmldir_part is deferred to be called in the root
+    # CMAKE_BINARY_DIR. If find_package(Qt6) is not called in the root of the project (like in the
+    # Qt Creator super repo), QT_CMAKE_EXPORT_NAMESPACE will not be defined.
+    # Manually define it here, based on the value passed to the function, from a scope where it
+    # is available.
+    set(QT_CMAKE_EXPORT_NAMESPACE "${qt_cmake_export_namespace}")
+
     set(effective_outdir $<TARGET_FILE_DIR:${target}>)
     set(qtconf_file "${effective_outdir}/${target}_qt.part.conf")
     get_target_property(dependency_targets "${target}" QT_QML_DEPENDENT_QML_MODULE_TARGETS)
@@ -1124,7 +1131,8 @@ Check https://doc.qt.io/qt-6/qt-cmake-policy-qtp0001.html for policy details."
             )
             cmake_language(EVAL CODE "
                     cmake_language(DEFER DIRECTORY [[${PROJECT_SOURCE_DIR}]]
-                        CALL _qt_internal_write_qmldir_part ${target})
+                        CALL _qt_internal_write_qmldir_part \"${target}\"
+                        \"${QT_CMAKE_EXPORT_NAMESPACE}\")
                 ")
         else()
             # Before CMake 3.19, we don't have DEFER, so we immediately write out the qt.conf
@@ -1168,12 +1176,20 @@ Check https://doc.qt.io/qt-6/qt-cmake-policy-qtp0001.html for policy details."
         if(NOT aotstats_setup_called)
             set_property(GLOBAL PROPERTY _qt_internal_deferred_aotstats_setup TRUE)
             cmake_language(EVAL CODE "cmake_language(DEFER DIRECTORY \"${CMAKE_BINARY_DIR}\" "
-                "CALL _qt_internal_deferred_aotstats_setup)")
+                "CALL _qt_internal_deferred_aotstats_setup \"${QT_CMAKE_EXPORT_NAMESPACE}\"
+            )")
         endif()
     endif()
 endfunction()
 
-function(_qt_internal_deferred_aotstats_setup)
+function(_qt_internal_deferred_aotstats_setup qt_cmake_export_namespace)
+    # _qt_internal_deferred_aotstats_setup is deferred to be called in the root
+    # CMAKE_BINARY_DIR. If find_package(Qt6) is not called in the root of the project (like in the
+    # Qt Creator super repo), QT_CMAKE_EXPORT_NAMESPACE will not be defined.
+    # Manually define it here, based on the value passed to the function, from a scope where it
+    # is available.
+    set(QT_CMAKE_EXPORT_NAMESPACE "${qt_cmake_export_namespace}")
+
     get_property(module_targets GLOBAL PROPERTY _qt_qml_aotstats_module_targets)
 
     set(onlybytecode_modules "")
@@ -1206,7 +1222,7 @@ function(_qt_internal_deferred_aotstats_setup)
             DEPENDS ${aotstats_files} ${module_aotstats_list_file}
             COMMAND
                 ${tool_wrapper}
-                $<TARGET_FILE:Qt6::qmlaotstats>
+                $<TARGET_FILE:${QT_CMAKE_EXPORT_NAMESPACE}::qmlaotstats>
                 aggregate
                 ${module_aotstats_list_file}
                 ${output}
@@ -1259,13 +1275,13 @@ function(_qt_internal_deferred_aotstats_setup)
         DEPENDS ${module_aotstats_targets} ${module_aotstats_files}
         COMMAND
             ${tool_wrapper}
-            $<TARGET_FILE:Qt6::qmlaotstats>
+            $<TARGET_FILE:${QT_CMAKE_EXPORT_NAMESPACE}::qmlaotstats>
             aggregate
             "${aotstats_list_file}"
             "${all_aotstats_file}"
         COMMAND
             ${tool_wrapper}
-            $<TARGET_FILE:Qt6::qmlaotstats>
+            $<TARGET_FILE:${QT_CMAKE_EXPORT_NAMESPACE}::qmlaotstats>
             format
             "${all_aotstats_file}"
             "${formatted_stats_file}"

tests/auto/cmake/RunCMake/CMakeLists.txt

@@ -5,6 +5,7 @@ _qt_internal_get_cmake_test_configure_options(config_flags)
 if(NOT CMAKE_CROSSCOMPILING)
     add_RunCMake_test(qt_target_qml_sources ${config_flags} "-D_Qt6CTestMacros=${_Qt6CTestMacros}")
 endif()
+add_RunCMake_test(export_namespace_in_root ${config_flags})
 
 _qt_internal_get_cmake_test_configure_options(option_list)
 add_RunCMake_test(generate_qmlls_ini ${option_list})

tests/auto/cmake/RunCMake/export_namespace_in_root/CMakeLists.txt

@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 3.16)
+project(${RunCMake_TEST} LANGUAGES CXX)
+
+add_subdirectory(Foo/Bar)
+add_subdirectory(app)

tests/auto/cmake/RunCMake/export_namespace_in_root/Foo/Bar/CMakeLists.txt

@@ -0,0 +1,21 @@
+find_package(Qt6 6.8 REQUIRED COMPONENTS Gui Quick REQUIRED)
+
+qt_standard_project_setup(REQUIRES 6.8)
+
+qt_add_qml_module(FooBar
+    URI Foo.Bar
+    VERSION 1.0
+    STATIC
+    SOURCES
+        foobar.h foobar.cpp
+    QML_FILES
+        FoobarQML.qml
+    IMPORTS
+        QtQuick
+)
+
+target_link_libraries(FooBar
+    PRIVATE
+        Qt6::Quick
+        Qt6::Gui
+)

tests/auto/cmake/RunCMake/export_namespace_in_root/Foo/Bar/FoobarQML.qml

@@ -0,0 +1,13 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+import QtQuick
+
+Item {
+    id: root
+
+    Rectangle {
+        anchors.fill: root
+        color: "green"
+    }
+}

tests/auto/cmake/RunCMake/export_namespace_in_root/Foo/Bar/foobar.cpp

@@ -0,0 +1,16 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include "foobar.h"
+
+#include <QPainter>
+
+void Foobar::paint(QPainter *painter)
+{
+    QPen pen(QColorConstants::Red, 2);
+    QBrush brush(QColorConstants::Red);
+
+    painter->setPen(pen);
+    painter->setBrush(brush);
+    painter->drawRect(0, 0, 100, 100);
+}

tests/auto/cmake/RunCMake/export_namespace_in_root/Foo/Bar/foobar.h

@@ -0,0 +1,16 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#pragma once
+
+#include <QtQuick/QQuickPaintedItem>
+
+class Foobar : public QQuickPaintedItem
+{
+    Q_OBJECT
+    QML_ELEMENT
+public:
+    using QQuickPaintedItem::QQuickPaintedItem;
+
+    void paint(QPainter *painter) override;
+};

tests/auto/cmake/RunCMake/export_namespace_in_root/RunCMakeTest.cmake

@@ -0,0 +1,24 @@
+include(RunCMake)
+
+include(${_Qt6CTestMacros})
+# Stub function to make `_qt_internal_get_cmake_test_configure_options` work
+function(_qt_internal_get_build_vars_for_external_projects)
+endfunction()
+
+_qt_internal_get_cmake_test_configure_options(config_flags)
+list(APPEND config_flags "-DCMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH}")
+
+function(run_cmake_and_build case)
+    # Set common build directory for configure and build
+    set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${case}-build)
+    run_cmake_with_options(${case} ${config_flags})
+    # Do not remove the current RunCMake_TEST_BINARY_DIR
+    set(RunCMake_TEST_NO_CLEAN 1)
+    run_cmake_command(${case}-build ${CMAKE_COMMAND} --build .)
+endfunction()
+
+if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.19"
+    AND RunCMake_GENERATOR MATCHES "^Ninja"
+)
+    run_cmake_and_build(export_namespace_in_root)
+endif()

tests/auto/cmake/RunCMake/export_namespace_in_root/app/CMakeLists.txt

@@ -0,0 +1,18 @@
+find_package(Qt6 6.8 COMPONENTS Quick REQUIRED)
+
+qt_standard_project_setup(REQUIRES 6.8)
+
+qt_add_executable(app app.cpp)
+qt_add_qml_module(app
+    URI ExampleProjectApp
+    VERSION 1.0
+    QML_FILES Main.qml
+    DEPENDENCIES
+        TARGET FooBar
+)
+
+target_link_libraries(app
+    PRIVATE
+        Qt6::Quick
+        FooBarplugin
+    )

tests/auto/cmake/RunCMake/export_namespace_in_root/app/Main.qml

@@ -0,0 +1,29 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+import QtQuick
+import Foo.Bar
+
+Window {
+    width: 640
+    height: 400
+    visible: true
+    title: qsTr("Example Project")
+
+    Foobar {
+        id: controls
+        anchors.left: parent.left
+        anchors.top: parent.top
+        anchors.margins: 20
+        width: 100
+        height: 100
+    }
+    FoobarQML {
+        id: rect
+        anchors.left: controls.right
+        anchors.top: parent.top
+        anchors.margins: 20
+        width: 100
+        height: 100
+    }
+}

tests/auto/cmake/RunCMake/export_namespace_in_root/app/app.cpp

@@ -0,0 +1,22 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include <QGuiApplication>
+#include <QQmlApplicationEngine>
+#include <QDebug>
+#include <QDirIterator>
+
+int main(int argc, char *argv[])
+{
+    QGuiApplication app(argc, argv);
+
+
+    QDirIterator dirIterator(":/", QDirIterator::Subdirectories);
+    while (dirIterator.hasNext()) {
+        qDebug() << dirIterator.next();
+    }
+    QQmlApplicationEngine engine;
+    engine.loadFromModule("ExampleProjectApp", "Main");
+
+    return app.exec();
+}