Subject: bug#26378: 26.0.50; Hitting 'n' during ediff gives Error

From: Kaushal Modi <[email-masked]>
Date: Thu, 06 Apr 2017 14:36:58 +0000

On Thu, Apr 6, 2017 at 8:44 AM <[email-masked]> wrote:

> Kaushal Modi <[email-masked]> writes:
>
> > +
> > +The PROGRAM is executed asynchronously unless `system-type' is
> > +`windows-nt' or `ms-dos', or unless SYNCH is non-nil.
>
> I think the second "unless" is redundant.
>

I prefer repeating 'unless' in this case where the subject is changing from
system-type to SYNCH. It just adds clarity. Though, grammatically what you
suggested is also correct. So for reducing redundancy, I'll go with your
suggestion.

> > I have tweaked this part slightly (see patch in this email). Based on the
> > code, nil and "" elements will be removed from a concatenated list of
> > OPTIONS and FILES; not just FILES.
>
> But OPTIONS can't have nil or "" in it (or any "elements", really), so I
> don't think there is any need to talk about that in the docstring.
>

That's correct. I've updated the patch with what you suggested earlier.

>From 086a11c99e77825befc466f65f213d4857618f6f Mon Sep 17 00:00:00 2001
From: Kaushal Modi <[email-masked]>
Date: Wed, 5 Apr 2017 17:16:33 -0400
Subject: [PATCH] Check that file argument is a string

* lisp/vc/ediff-diff.el (ediff-exec-process): Check that the argument
  passed to `file-local-copy' is a string (Bug#26378).  Also fix
  the existing comment for this function, and convert it to its
  doc-string.
---
 lisp/vc/ediff-diff.el | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/lisp/vc/ediff-diff.el b/lisp/vc/ediff-diff.el
index cfa08ef360..ded82c41c9 100644
--- a/lisp/vc/ediff-diff.el
+++ b/lisp/vc/ediff-diff.el
@@ -1134,12 +1134,20 @@ ediff-setup-diff-regions3
    ))

-;; Execute PROGRAM asynchronously, unless OS/2, Windows-*, or DOS, or
unless
-;; SYNCH is non-nil.  BUFFER must be a buffer object, and must be alive.
The
-;; OPTIONS arg is a list of options to pass to PROGRAM. It may be a blank
-;; string.  All elements in FILES must be strings.  We also delete nil from
-;; args.
 (defun ediff-exec-process (program buffer synch options &rest files)
+  "Execute the diff PROGRAM.
+
+The PROGRAM output is sent to BUFFER, which must be a live buffer
+object.
+
+The PROGRAM is executed asynchronously unless `system-type' is
+`windows-nt' or `ms-dos', or SYNCH is non-nil.
+
+OPTIONS is a string of space-separated options to pass to PROGRAM.  It
+may be a blank string.
+
+FILES is a list of filenames to pass to PROGRAM; nil and \"\" elements
+are ignored."
   (let ((data (match-data))
  ;; If this is a buffer job, we are diffing temporary files
  ;; produced by Emacs with ediff-coding-system-for-write, so
@@ -1151,8 +1159,9 @@ ediff-exec-process
  args)
     (setq args (append (split-string options)
                        (mapcar (lambda (file)
-                                 (file-name-unquote
-                                  (or (file-local-copy file) file)))
+                                 (when (stringp file)
+                                   (file-name-unquote
+                                    (or (file-local-copy file) file))))
                                files)))
     (setq args (delete "" (delq nil args))) ; delete nil and "" from
arguments
     ;; the --binary option, if present, should be used only for buffer jobs
-- 
2.11.0

-- 

Kaushal Modi