Make dabbrev use the buffer's file name as a source for completions

* lisp/dabbrev.el (dabbrev--find-expansion): Include the buffer's
file name in the completions (bug#8163).

1 files changed, 35 insertions, 13 deletions

diff --git a/lisp/dabbrev.el b/lisp/dabbrev.el
index b04128cf677..8f8d553cdab 100644
--- a/lisp/dabbrev.el
+++ b/lisp/dabbrev.el
@@ -551,8 +551,9 @@ See also `dabbrev-abbrev-char-regexp' and \\[dabbrev-completion]."
       (if (not (or (eq dabbrev--last-buffer dabbrev--last-buffer-found)
                    (minibuffer-window-active-p (selected-window))))
           (progn
-            (message "Expansion found in `%s'"
-                     (buffer-name dabbrev--last-buffer))
+            (when (buffer-name dabbrev--last-buffer)
+              (message "Expansion found in `%s'"
+                       (buffer-name dabbrev--last-buffer)))
             (setq dabbrev--last-buffer-found dabbrev--last-buffer))
         (message nil))
       (if (and (or (eq (current-buffer) dabbrev--last-buffer)
@@ -770,17 +771,38 @@ of the start of the occurrence."
                  (make-progress-reporter
                   "Scanning for dabbrevs..."
                   (- (length dabbrev--friend-buffer-list)) 0 0 1 1.5))))
-       ;; Walk through the buffers till we find a match.
-       (let (expansion)
-         (while (and (not expansion) dabbrev--friend-buffer-list)
-           (setq dabbrev--last-buffer (pop dabbrev--friend-buffer-list))
-           (set-buffer dabbrev--last-buffer)
-           (progress-reporter-update dabbrev--progress-reporter
-                                     (- (length dabbrev--friend-buffer-list)))
-           (setq dabbrev--last-expansion-location (point-min))
-           (setq expansion (dabbrev--try-find abbrev nil 1 ignore-case)))
-         (progress-reporter-done dabbrev--progress-reporter)
-         expansion)))))
+       (let ((file-name (buffer-file-name))
+             file-name-buffer)
+         (unwind-protect
+             (progn
+               ;; Include the file name components into the abbrev
+               ;; list (because if you have a file name "foobar", it's
+               ;; somewhat likely that you'll be talking about foobar
+               ;; stuff in the file itself).
+               (when file-name
+                 (setq file-name-buffer (generate-new-buffer " *abbrev-file*"))
+                 (with-current-buffer file-name-buffer
+                   (dolist (part (file-name-split file-name))
+                     (insert part "\n")))
+                 (setq dabbrev--friend-buffer-list
+                       (append dabbrev--friend-buffer-list
+                               (list file-name-buffer))))
+               ;; Walk through the buffers till we find a match.
+               (let (expansion)
+                 (while (and (not expansion) dabbrev--friend-buffer-list)
+                   (setq dabbrev--last-buffer
+                         (pop dabbrev--friend-buffer-list))
+                   (set-buffer dabbrev--last-buffer)
+                   (progress-reporter-update
+                    dabbrev--progress-reporter
+                    (- (length dabbrev--friend-buffer-list)))
+                   (setq dabbrev--last-expansion-location (point-min))
+                   (setq expansion (dabbrev--try-find
+                                    abbrev nil 1 ignore-case)))
+                 (progress-reporter-done dabbrev--progress-reporter)
+                 expansion))
+           (when (buffer-live-p file-name-buffer)
+             (kill-buffer file-name-buffer))))))))
 
 ;; Compute the list of buffers to scan.
 ;; If dabbrev-search-these-buffers-only, then the current buffer