[Reg 5.13 -> 5.14] Application is crashed on qmlRegisterSingletonType function call with clang and libc++ environment

uQML app being crashed after running template version of function qmlRegisterSingletonType.
App is compiled with libc++ and clang-9 compiler using linux-clang-libc++ qt mkspec.
Problem began since Qt 5.14.2 up to Qt 5.15.2. With Qt 5.13.2 works well. Test project is included.

 How to reproduce:
1. Open test project
2. Build project.
4. Start the application.
What happens:
1. Application crashes
2. Output:

19:33:08: Starting /home/tayursky-k/dev/build-SingletonQMLCpp-Desktop_Qt_5_12_0_CLang_64bit-Debug/SingletonQMLCpp ...
QML debugging is enabled. Only use this in a safe environment.
qmlRegisterSingletonType ___1
19:33:08: The program has unexpectedly finished.
19:33:08: The process was ended forcefully.
19:33:08: /home/tayursky-k/dev/build-SingletonQMLCpp-Desktop_Qt_5_12_0_CLang_64bit-Debug/SingletonQMLCpp crashed.

Problem applies to both debug and release builds.