If a qml project is compiled with the Qt Quick compiler enabled the corresponding myfile_qml.cpp is correctly generated but inside the executable, using a normal text editor like Notepad+, is possible to see the full qml sources. Try to compile the project in attach with Qt Quick compiler enabled (is enabled by default). The compilation results are the two files main_qml.cpp and main_qml.o as consequence of compilation of main.qml. However if you open the qmlTest.exe with notepad+ you can see find inside the exe the full main.qml source clearly visible:

import QtQuick 2.12
import QtQuick.Window 2.12
Window {
 width: 640
 height: 480
 visible: true
 title: qsTr("Hello World")
}

I verified this issue with Qt Creator using Mingw and android compilation but it also happear using Visual Studio with Qt Plugin.

NOTE: After checked the Qt sources I thought the bug report needed to be opened in the Qt project section. I opened the same report here, feel free to remove this report if you think is useless.