bug#19140: dir-locals-collect-variables discrepancy in handling non-file buffers

[Ivan Shmakov]

>>>>> Katsumi Yamaoka <yamaoka@jpl.org> writes:
>>>>> On Tue, 30 Dec 2014 19:45:57 +0000, Ivan Shmakov wrote:

[…]

 >> * lisp/files.el (dir-locals-collect-variables): Use
 >> default-directory in place of the file name while working on
 >> non-file buffers (as hack-dir-local-variables already does.)

 > After this change, I got to get unknown errors[1] when building
 > Ma Gnus.  To reproduce the same result, try the following in the
 > Emacs source tree:

 > % cd lisp/gnus 
 > % emacs -batch -Q --eval FORM 

 > where FORM is:

 > '(with-temp-buffer (let ((default-directory (expand-file-name ".")))
 > (insert-file-contents "./auth-source.el") (hack-local-variables)))'

 > And you will see

 > (args-out-of-range "/DIR/emacs/lisp/gnus" 21 nil)

 > or something similar (where 21 is 1+ the number of letters of the dir
 > name).

 > The FORM above is what `custom-make-dependencies' does.

        ACK, thanks.  Indeed, this change assumes that the result for
        (expand-file-name default-directory) ends with a ‘/’, yet that’s
        only the case when default-directory itself ends with a ‘/’,
        which I believe it should; consider, e. g.:

(defun cd-absolute (dir)
  "Change current directory to given absolute file name DIR."
  ;; Put the name into directory syntax now,
  ;; because otherwise expand-file-name may give some bad results.
  (setq dir (file-name-as-directory dir))
  …)

        The issue at hand could be solved by using the first of the
        patches MIMEd.  However, I believe that such a change may easily
        mask bugs in the other parts of the code, so the proper solution
        would probably be a fix to custom-make-dependencies, as per the
        second patch MIMEd.

        Could you please check if both indeed resolve the issue at hand?

        TIA.

[…]

-- 
FSF associate member #7257  http://boycottsystemd.org/  … 3013 B6A0 230E 334A

--- a/lisp/files.el     2015-01-17 19:02:00 +0000
+++ b/lisp/files.el
@@ -3604,7 +3604,8 @@ defun dir-locals-collect-variables (class-variables root 
variables)
 Return the new variables list."
   (let* ((file-name (or (buffer-file-name)
                        ;; Handle non-file buffers, too.
-                       (expand-file-name default-directory)))
+                       (file-name-as-directory
+                        (expand-file-name default-directory))))
         (sub-file-name (if file-name
                             ;; FIXME: Why not use file-relative-name?
                            (substring file-name (length root)))))

--- a/lisp/cus-dep.el   2015-01-01 22:26:41 +0000
+++ b/lisp/cus-dep.el   2015-01-19 08:49:23 +0000
@@ -62,7 +62,8 @@ defun custom-make-dependencies ()
       (while (setq subdir (pop command-line-args-left))
         (message "Directory %s" subdir)
         (let ((files (directory-files subdir nil "\\`[^=.].*\\.el\\'"))
-              (default-directory (expand-file-name subdir))
+              (default-directory
+               (file-name-as-directory (expand-file-name subdir)))
               (preloaded (concat "\\`\\(\\./+\\)?"
                                  (regexp-opt preloaded-file-list t)
                                  "\\.el\\'")))