━━━━━━━━━━━━━━━━━━━━━━━━
                         PLN CDR DRAFT: ISSUE 5

                                Gleefre
                        ━━━━━━━━━━━━━━━━━━━━━━━━





1 Issue 5 (Local nickname shadowing package's own name)
═══════════════════════════════════════════════════════

1.1 Description
───────────────

  It is not clear whether it should be allowed to define a /local
  nickname/ that shadows the /name/ or one of the /global nicknames/ of
  the package that it is defined in.


1.2 Examples
────────────

  ┌────
  │ (defpackage #:foo
  │   (:use)
  │   (:nicknames #:bar)
  │   (:local-nicknames (#:foo #:cl)
  │                     (#:bar #:cl)))
  │ ; => continuable error  (sbcl, ccl, abcl)
  │ ; => error  (lispworks)
  │ ; => ok  (ecl, acl, clasp)
  └────


1.3 Current behavior
────────────────────

  sbcl, ccl, abcl: A correctable error is signaled by `defpackage'.

  lispworks: An error is signaled by `defpackage'.  A correctable error
    is signaled by `add-package-local-nickname'.

  ecl, acl, clasp: No errors are signaled.


1.4 Proposal ALLOW-WITH-STYLE-WARNING
─────────────────────────────────────

  It should be allowed to use the name or one of the global nicknames of
  the package as a local nickname, but a style warning might be issued.


1.4.1 Rationale
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  Such local nicknames are not likely to break anything. Even though
  they can be a bit confusing, this alone does not warrant an error to
  be signaled.

  Moreover, on all implementations it is possible to obtain such
  nicknames, even if on some of them invoking the `continue' restart is
  required. This suggests that cost of adoption is very low.


1.5 Proposal DISALLOW-WITH-CORRECTABLE-ERROR
────────────────────────────────────────────

  Attemts to create such a nickname should result in a correctable error
  being signaled. The `continue' restart can be used to create the
  nickname anyway.