(comint-send-input): Handle comint-process-echoes

differently.

lisp/comint.el

@@ -1422,9 +1422,7 @@ Similarly for Soar, Scheme, etc."
 			    (delete-region pmark start)
 			    copy))))
 
-	  (if comint-process-echoes
-	      (delete-region pmark (point))
-	    (insert ?\n))
+	  (insert ?\n)
 
 	  (comint-add-to-input-history history)
 
@@ -1469,6 +1467,29 @@ Similarly for Soar, Scheme, etc."
 	  ;; clear the "accumulation" marker
 	  (set-marker comint-accum-marker nil)
 	  (funcall comint-input-sender proc input)
+
+	  ;; Optionally delete echoed input (after checking it).
+ 	  (if comint-process-echoes
+	      (let* ((echo-len (- comint-last-input-end
+				  comint-last-input-start))
+		     (echo-end (+ comint-last-input-end echo-len)))
+		;; Wait for all input to be echoed:
+		(while (and (accept-process-output proc)
+			    (> echo-end (point-max))
+			    (= 0 (compare-buffer-substrings
+				  nil comint-last-input-start
+				  (- (point-max) echo-len)
+				  ;; Above difference is equivalent to
+				  ;; (+ comint-last-input-start
+				  ;;    (- (point-max) comint-last-input-end))
+				  nil comint-last-input-end (point-max)))))
+ 		(if (and
+ 		     (<= echo-end (point-max))
+ 		     (= 0 (compare-buffer-substrings
+ 			   nil comint-last-input-start comint-last-input-end
+ 			   nil comint-last-input-end echo-end)))
+ 		    (delete-region comint-last-input-end echo-end))))
+
 	  ;; This used to call comint-output-filter-functions,
 	  ;; but that scrolled the buffer in undesirable ways.
 	  (run-hook-with-args 'comint-output-filter-functions "")))))
@@ -1540,7 +1561,7 @@ This function should be in the list `comint-output-filter-functions'."
 		(delete-char -2)))))))))
 
 (add-hook 'comint-output-filter-functions 'comint-carriage-motion)
-    
+
 ;; The purpose of using this filter for comint processes
 ;; is to keep comint-last-input-end from moving forward
 ;; when output is inserted.