Follow Symbol Under Cursor broken on _Nullable keyword

When extension-related keywords such as _Nullable are present, "Follow Symbol Under Cursor" will correctly go to the declaration, however it won't go to the definition.
Attached is a simple example.

1. Hit F2 on MyClass::isValid in main.cpp and it will correctly go to main.h
2. Hit F2 again on the declaration in main.h, and it won't go to main.cpp (bug)

In order to hit this bug, QtCreator kits must be configured to use Clang-7 as shown in the attached picture
UPDATE: Also affects default GCC Kit

This is on Ubuntu 18.04 running QtCreator 4.9.1
Clang Code Model plugin is active

WORKAROUND:

A workaround at the time being is to wrap these special keywords around macros, and avoid them to be parsed by the legacy code parser

#if __clang__ && !defined( Q_CREATOR_RUN )
	#define my_nullable _Nullable
	#define my_nonnull _Nonnull
#else
	#define my_nullable
	#define my_nonnull
#endif

Alternatively:

#if defined( Q_CREATOR_RUN )
	#define _Nullable
	#define _Nonnull
#endif