The following two test cases...

  contextDecl-018, contextDecl-019

contain the following queries:

  declare context item := last() + 1; .
  declare context item := position() + 1; .

I would expect XQDY0054 to be valid alternative error codes, because position() or last() create circular dependencies as well (at runtime, at the latest).

As an alternative, error code XPDY0002 could be allowed as alternative for the following three queries:

  contextDecl-015, contextDecl-053, extvardef-015