(comint-read-input-ring, comint-write-input-ring):

Treat "" like nil in comint-input-ring-file-name.

diff --git a/lisp/comint.el b/lisp/comint.el
index 81e48cd209a71f4ccd5f48d83b18f90d35a61df3..4705d43546ba10f4e7ccd6ea5f1eaaf6c3e85d8d 100644 (file)
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -611,7 +611,8 @@ Useful within mode or mode hooks.
 The structure of the history file should be one input command per line, and
 most recent command last.
 See also `comint-input-ignoredups' and `comint-write-input-ring'."
-  (cond ((null comint-input-ring-file-name)
+  (cond ((or (null comint-input-ring-file-name)
+            (equal comint-input-ring-file-name ""))
         nil)
        ((not (file-readable-p comint-input-ring-file-name))
         (message "Cannot read history file %s" comint-input-ring-file-name))
@@ -650,6 +651,7 @@ Useful within process sentinels.
 
 See also `comint-read-input-ring'."
   (cond ((or (null comint-input-ring-file-name)
+            (equal comint-input-ring-file-name "")
             (null comint-input-ring) (ring-empty-p comint-input-ring))
         nil)
        ((not (file-writable-p comint-input-ring-file-name))