org-agenda: Fix small bug

* lisp/org-agenda.el (org-agenda-get-day-entries): Rewrite function to
  avoid O(n^2) complexity.  Also fix empty deadline list passed as
  argument when :deadline (or :deadline*) is not the first symbol.

lisp/org-agenda.el

@@ -5313,61 +5313,60 @@ FILE is the path to a file to be checked for entries.  DATE is date like
 the one returned by `calendar-current-date'.  ARGS are symbols indicating
 which kind of entries should be extracted.  For details about these, see
 the documentation of `org-diary'."
-  (setq args (or args org-agenda-entry-types))
   (let* ((org-startup-folded nil)
 	 (org-startup-align-all-tables nil)
-	 (buffer (if (file-exists-p file)
-		     (org-get-agenda-file-buffer file)
-		   (error "No such file %s" file)))
-	 arg results rtn deadline-results)
+	 (buffer (if (file-exists-p file) (org-get-agenda-file-buffer file)
+		   (error "No such file %s" file))))
     (if (not buffer)
-	;; If file does not exist, make sure an error message ends up in diary
+	;; If file does not exist, signal it in diary nonetheless.
 	(list (format "ORG-AGENDA-ERROR: No such org-file %s" file))
       (with-current-buffer buffer
 	(unless (derived-mode-p 'org-mode)
 	  (error "Agenda file %s is not in `org-mode'" file))
 	(setq org-agenda-buffer (or org-agenda-buffer buffer))
-	(let ((case-fold-search nil))
-	  (save-excursion
-	    (save-restriction
-	      (if (eq buffer org-agenda-restrict)
-		  (narrow-to-region org-agenda-restrict-begin
-				    org-agenda-restrict-end)
-		(widen))
-	      ;; The way we repeatedly append to `results' makes it O(n^2) :-(
-	      (while (setq arg (pop args))
-		(cond
-		 ((and (eq arg :todo)
-		       (equal date (calendar-gregorian-from-absolute
-				    (org-today))))
-		  (setq rtn (org-agenda-get-todos))
-		  (setq results (append results rtn)))
-		 ((eq arg :timestamp)
-		  (setq rtn (org-agenda-get-blocks))
-		  (setq results (append results rtn))
-		  (setq rtn (org-agenda-get-timestamps deadline-results))
-		  (setq results (append results rtn)))
-		 ((eq arg :sexp)
-		  (setq rtn (org-agenda-get-sexps))
-		  (setq results (append results rtn)))
-		 ((eq arg :scheduled)
-		  (setq rtn (org-agenda-get-scheduled deadline-results))
-		  (setq results (append results rtn)))
-		 ((eq arg :scheduled*)
-		  (setq rtn (org-agenda-get-scheduled deadline-results t))
-		  (setq results (append results rtn)))
-		 ((eq arg :closed)
-		  (setq rtn (org-agenda-get-progress))
-		  (setq results (append results rtn)))
-		 ((eq arg :deadline)
-		  (setq rtn (org-agenda-get-deadlines))
-		  (setq deadline-results (copy-sequence rtn))
-		  (setq results (append results rtn)))
-		 ((eq arg :deadline*)
-		  (setq rtn (org-agenda-get-deadlines t))
-		  (setq deadline-results (copy-sequence rtn))
-		  (setq results (append results rtn))))))))
-	results))))
+	(save-excursion
+	  (save-restriction
+	    (if (eq buffer org-agenda-restrict)
+		(narrow-to-region org-agenda-restrict-begin
+				  org-agenda-restrict-end)
+	      (widen))
+	    ;; Rationalize ARGS.  Also make sure `:deadline' comes
+	    ;; first in order to populate DEADLINES before passing it.
+	    ;;
+	    ;; We use `delq' since `org-uniquify' duplicates ARGS,
+	    ;; guarding us from modifying `org-agenda-entry-types'.
+	    (setf args (org-uniquify (or args org-agenda-entry-types)))
+	    (when (and (memq :scheduled args) (memq :scheduled* args))
+	      (setf args (delq :scheduled* args)))
+	    (cond
+	     ((memq :deadline args)
+	      (setf args (cons :deadline
+			       (delq :deadline (delq :deadline* args)))))
+	     ((memq :deadline* args)
+	      (setf args (cons :deadline* (delq :deadline* args)))))
+	    ;; Collect list of headlines.  Return them flattened.
+	    (let ((case-fold-search nil) results deadlines)
+	      (dolist (arg args (apply #'nconc (nreverse results)))
+		(pcase arg
+		  ((and :todo (guard (org-agenda-today-p date)))
+		   (push (org-agenda-get-todos) results))
+		  (:timestamp
+		   (push (org-agenda-get-blocks) results)
+		   (push (org-agenda-get-timestamps deadlines) results))
+		  (:sexp
+		   (push (org-agenda-get-sexps) results))
+		  (:scheduled
+		   (push (org-agenda-get-scheduled deadlines) results))
+		  (:scheduled*
+		   (push (org-agenda-get-scheduled deadlines t) results))
+		  (:closed
+		   (push (org-agenda-get-progress) results))
+		  (:deadline
+		   (setf deadlines (org-agenda-get-deadlines))
+		   (push deadlines results))
+		  (:deadline*
+		   (setf deadlines (org-agenda-get-deadlines t))
+		   (push deadlines results)))))))))))
 
 (defsubst org-em (x y list)
   "Is X or Y a member of LIST?"