*** complete.el	Tue Jan 23 07:40:00 2007
--- complete.el	Wed Mar  7 11:21:16 2007
***************
*** 383,388 ****
--- 383,411 ----
      (let ((completion-ignore-case nil))
        (test-completion str table pred))))

+ ;; The following function is an attempt to work around two problems:
+ 
+ ;; (1) When complete.el was written, (try-completion "" '(("") (""))) used to
+ ;; return the value "".  With a change from 2002-07-07 it returns t which caused
+ ;; `PC-lisp-complete-symbol' to fail with a "Wrong type argument: sequencep, t"
+ ;; error.  `PC-try-completion' returns STRING in this case.
+ 
+ ;; (2) (try-completion "" '((""))) returned t before the above-mentioned change.
+ ;; Since `PC-chop-word' operates on the return value of `try-completion' this
+ ;; case might have provoked a similar error as in (1).  `PC-try-completion'
+ ;; returns "" instead.  I don't know whether this is a real problem though.
+ 
+ ;; Since `PC-try-completion' is not a guaranteed to fix these bugs reliably, you
+ ;; should try to look at the following discussions when you encounter problems:
+ ;; - emacs-pretest-bug ("Partial Completion" starting 2007-02-23),
+ ;; - emacs-devel ("[address-of-OP: Partial completion]" starting 2007-02-24),
+ ;; - emacs-devel ("[address-of-OP: EVAL and mouse selection in *Completions*]"
+ ;;   starting 2007-03-05).
+ (defun PC-try-completion (string alist &optional predicate)
+   "Like `try-completion' but return STRING instead of t."
+   (let ((result (try-completion string alist predicate)))
+     (if (eq result t) string result)))
+ 
  (defun PC-do-completion (&optional mode beg end)
    (or beg (setq beg (minibuffer-prompt-end)))
    (or end (setq end (point-max)))
***************
*** 623,630 ****

  	    ;; Check if next few letters are the same in all cases
  	    (if (and (not (eq mode 'help))
! 		     (setq prefix (try-completion (PC-chunk-after basestr skip)
!                                                   poss)))
  		(let ((first t) i)
  		  ;; Retain capitalization of user input even if
  		  ;; completion-ignore-case is set.
--- 646,653 ----

  	    ;; Check if next few letters are the same in all cases
  	    (if (and (not (eq mode 'help))
! 		     (setq prefix (PC-try-completion
! 				   (PC-chunk-after basestr skip) poss)))
  		(let ((first t) i)
  		  ;; Retain capitalization of user input even if
  		  ;; completion-ignore-case is set.
***************
*** 662,668 ****
  			      (setq skip (concat skip
  						 (regexp-quote prefix)
  						 PC-ndelims-regex)
! 				    prefix (try-completion
  					    (PC-chunk-after
  					     ;; not basestr, because that does
  					     ;; not reflect insertions
--- 685,691 ----
  			      (setq skip (concat skip
  						 (regexp-quote prefix)
  						 PC-ndelims-regex)
! 				    prefix (PC-try-completion
  					    (PC-chunk-after
  					     ;; not basestr, because that does
  					     ;; not reflect insertions
***************
*** 996,1002 ****
                (cond
                 ((not completion-table) nil)
                 ((eq action 'lambda) (test-completion str2 completion-table nil))
!                ((eq action nil) (try-completion str2 completion-table nil))
                 ((eq action t) (all-completions str2 completion-table nil)))))
      ad-do-it))
  
--- 1019,1025 ----
                (cond
                 ((not completion-table) nil)
                 ((eq action 'lambda) (test-completion str2 completion-table nil))
!                ((eq action nil) (PC-try-completion str2 completion-table nil))
                 ((eq action t) (all-completions str2 completion-table nil)))))
      ad-do-it))