Warning in <MyClass>: The data members of MyClass will not be stored, because it inherits from TObject but does not have its own ClassDef

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8

Well having a LinkDef let you control more carefully what the dictionary does and would give you an opportunity to suppress the warnings.

Alternatively you could try a relatively new alternative (so you mileage may vary) and remove the dictionary generation altogether and add a ClassDefInline macro (instead of the ClassDef macro).
If it works in you case, it will simply your build while still letting you use forward declaration.

Cheers,
Philippe.