Q: ARRAY[expanded_type] conforms to ARRAY[ANY]?

Hi,

a system that compiled fine with the snapshot of v5.7 failed to compile on
v5.6 with the following message:

Error code: VTCG
Error: actual generic parameter does not conform to constraint.
What to do: make sure that actual parameter is a type conforming to the
  constraint (the type appearing after `->' for the corresponding formal).

Class: TEST
Feature: invariant
In declaration: ARRAY [EXPANDED_TYPE]

For type: ARRAY [EXPANDED_TYPE]
Argument number: 1:
Actual generic parameter: EXPANDED_TYPE
Type to which it should conform: ANY

-------------------------------------------------------------------------------Degree:
4 Processed: 2 To go: 0 Total: 2

Now I'm wondering: am I wrong, or the compiler?

Source is:
indexing
        description     : "Test for VTCG"

class
        TEST

create
        test

feature -- Initialization

        test is
                        -- Creation procedure.
                do
                        --| Add your code here
                end

feature -- Test

        a : ARRAY[EXPANDED_TYPE]

invariant
        test: a /= Void

end -- class TEST

indexing
        description: "Test"

expanded class
        EXPANDED_TYPE

feature -- Test

        item : BIT 3

end -- class EXPANDED_TYPE

system
        VTCG_test

root
        TEST: "test"

default
        assertion (require)
        multithreaded (no)
        console_application (no)
        dynamic_runtime (no)
        dead_code_removal (yes)
        profile (no)
        line_generation (no)
        array_optimization (no)
        inlining (no)
        inlining_size ("10")


cluster

        test: "."

                -- EiffelBase
        library base:                           "$ISE_EIFFEL/library/base"
                exclude
                        "table_eiffel3";"desc"
                end
end

Regards,
Ulrich
P.S. Also posted as issue 10568 at eiffel.com