VALIDITY VDRS

ETL2 p.159, ETR p.37:
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Redefine Subclause rule

Consider a class C with a parent B. If a Parent part for B in C
contains a Redefine subclause, that clause is valid if and only
if every Feature_identifier fname that it lists (in its
Feature_list) satisfies the following conditions:
1. fname is the final name in C of a feature inherited from B.
2. That feature was not frozen, and was not a constant attribute.
3. fname appears only once in the Feature_list.
4. The Features part of C contains one Feature_declaration for
   fname, which is a valid redeclaration, but not an effecting,
   of the original feature.
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TEST DESCRIPTION:
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The Redefine subclause of parent CC in class BB lists twice
the same feature name `f'. Validity VDRS-3 is violated.
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TEST RESULTS:
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ISE Eiffel 5.0.016:    OK
SmallEiffel -0.76:     OK
Halstenbach 3.2:       OK
gelint:                OK
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TEST CLASSES:
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class AA

create

	make

feature

	make
		local
			b: BB
		do
			!! b
			b.f
		end

end -- class AA
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class BB

inherit

	CC
		redefine
			f, f
		end

feature

	f
		do
			print ("BB%N")
		end

end -- class BB
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class CC

feature

	f
		do
			print ("CC%N")
		end

end -- class CC
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