Cairo Error

%lang starknet

from starkware.cairo.common.alloc import alloc

struct Foo:
    member val: felt
end


func make_foo(value: felt) -> (foo: Foo):
    let foo = Foo(
        val=value,
    )
    return (foo)
end


func make_foo_array() -> (entry: Foo*):
    let (struct_array : Foo*) = alloc()

    let foo0 = make_foo(0)
    assert struct_array[0] = foo0
    return (struct_array)
end


@external
func test_make_foo{syscall_ptr : felt*, range_check_ptr}():
    let (foo_array) = make_foo_array()
    return ()
end

#   File "starkware/cairo/lang/compiler/preprocessor/preprocessor.py", line 1223, in visit_CodeElementCompoundAssertEq
#  starkware.cairo.lang.compiler.preprocessor.preprocessor_error.PreprocessorError: contracts/tests/test_foo.cairo:22:5: Cannot compare '__main__.Foo' and '(foo : __main__.Foo)'.