We have been able to reproduce, it has nothing to do with precompiled library.

Indeed we can see

		ensure -- from SET_TESTS
			monomorphic: Result.generating_type ~ {detachable like some_immediate_set_of_references_dscr}
		ensure -- from ELEMENT_TESTS
O			monomorphic: Result.generating_type ~ {detachable SET [detachable separate CHARACTER_8_REF, REFERENCE_EQUALITY [detachable separate CHARACTER_8_REF]]}
O		end