Example of Q_FLAG_NS not functioning

App.cpp

#include "App.h"

App.h

#ifndef APP_H_BYLS6KFN
#define APP_H_BYLS6KFN

#include <QObject>

namespace App {
    Q_NAMESPACE

    enum class ComponentRequirementState
    {
        NotRequired        = 0x0,
        RequiredForStartup = 0x01,
        AlwaysRequired     = 0x02,
        testme = NotRequired | AlwaysRequired
    };
    Q_FLAG_NS(ComponentRequirementState)
}

#endif /* end of include guard: APP_H_BYLS6KFN */

/* vim: set ts=4 sw=4 sts=4 expandtab ffs=unix,dos : */

CMakeLists.txt

project(appex)
cmake_minimum_required(VERSION 3.0)

set(Qt_VERSION_RELEASE 5 CACHE STRING "Qt release version")
set(Qt_VERSION_MAJOR   9 CACHE STRING "Qt major version")
set(Qt_VERSION_MINOR   3 CACHE STRING "Qt minor version")
set(Qt_VERSION ${Qt_VERSION_RELEASE}.${Qt_VERSION_MAJOR}.${Qt_VERSION_MINOR})

set(CMAKE_CXX_FLAGS "-std=c++11")

# Guess at where Qt can be found.
find_path(Qt_DIR
	NAME lib/cmake/Qt5/Qt5Config.cmake
	PATHS
		/opt/Qt${Qt_VERSION}/${Qt_VERSION}/gcc_64
		/opt/Qt${Qt_VERSION}/${Qt_VERSION_RELEASE}.${Qt_VERSION_MAJOR}/gcc_64
	DOC "Qt's ${COMPILER_ARCH} directory"
	NO_DEFAULT_PATH
)
message("Using Qt Directory: ${Qt_DIR}")


list(APPEND Qt_COMPONENTS Core)
foreach(pkg IN ITEMS ${Qt_COMPONENTS})
	# Qt_DEPS are our link targets.
	list(APPEND Qt_DEPS Qt${Qt_VERSION_RELEASE}::${pkg})
endforeach()
unset(pkg_name)
find_package(
	Qt${Qt_VERSION_RELEASE} REQUIRED
	COMPONENTS ${Qt_COMPONENTS}
	PATHS ${Qt_DIR}/lib/cmake/Qt${Qt_VERSION_RELEASE}
)

add_executable(app main.cpp App.h App.cpp)
target_link_libraries(app
	${Qt_DEPS}
)

# vim: ts=4 sw=4 sts=0 noet ft=cmake ffs=unix,dos :

main.cpp

#include <iostream>
#include <QtCore>
#include "App.h"

auto main(int argc, char *argv[]) -> int
{
    QCoreApplication app(argc, argv);
    app.setApplicationName("app");

    auto r = App::ComponentRequirementState::NotRequired;
    r = r | App::ComponentRequirementState::AlwaysRequired;
    std::cout << "r = " << static_cast<unsigned int>(r) << std::endl;

    return app.exec();
}

/* vim: set ts=4 sw=4 sts=4 expandtab ffs=unix,dos : */