After some investigations, I found out that the debug build is successful if the constructors of PointerTo, ConstPointerTo and PointerToBase are made ALWAYS_INLINE.
That is in panda/src/express/pointerTo.h I put
...
ALWAYS_INLINE CONSTEXPR PointerTo() NOEXCEPT DEFAULT_CTOR;
...
ALWAYS_INLINE CONSTEXPR ConstPointerTo() NOEXCEPT DEFAULT_CTOR;
...and in panda/src/express/pointerToBase.h I put
ALWAYS_INLINE CONSTEXPR PointerToBase() NOEXCEPT DEFAULT_CTOR;