(visit-tags-tbale-buffer): If CONT is stringp, use it for tags-file-name.

Don't bother calling tags-table-including when buffer-file-name is nil.
(visit-tags-table): Signal error FILE is not stringp.
Call visit-tags-table-buffer with FILE instead of 'same.
(tags-next-table): When restoring state vars, set tags-file-name too.

1 files changed, 25 insertions, 14 deletions

diff --git a/lisp/progmodes/etags.el b/lisp/progmodes/etags.el
index 72d30c935b6..a3b51141168 100644
--- a/lisp/progmodes/etags.el
+++ b/lisp/progmodes/etags.el
@@ -184,12 +184,14 @@ file the tag was in."
                                                        default-directory)
                                      t)
                      current-prefix-arg))
-  ;; Calling visit-tags-table-buffer with tags-file-name set to FILE will
-  ;; initialize a buffer for FILE and set tags-file-name to the
+  (or (stringp file) (signal 'wrong-type-argument (list 'stringp file)))
+  ;; Bind tags-file-name so we can control below whether the local or
+  ;; global value gets set.  Calling visit-tags-table-buffer will
+  ;; initialize a buffer for the file and set tags-file-name to the
   ;; fully-expanded name.
   (let ((tags-file-name file))
     (save-excursion
-      (or (visit-tags-table-buffer 'same)
+      (or (visit-tags-table-buffer file)
           (signal 'file-error (list "Visiting tags table"
                                     "file does not exist"
                                     file)))
@@ -237,6 +239,7 @@ file the tag was in."
               ;; Restore the state variables.
               (setq tags-table-list
                     (nth 0 (car tags-table-parent-pointer-list))
+                    tags-file-name (car tags-table-list)
                     tags-table-list-pointer
                     (nth 1 (car tags-table-parent-pointer-list))
                     tags-table-list-started-at
@@ -411,6 +414,7 @@ file the tag was in."
 
 (defun visit-tags-table-buffer (&optional cont)
   "Select the buffer containing the current tags table.
+If optional arg is a string, visit that file as a tags table.
 If optional arg is t, visit the next table in `tags-table-list'.
 If optional arg is the atom `same', don't look for a new table;
  just select the buffer visiting `tags-file-name'.
@@ -427,7 +431,7 @@ Returns t if it visits a tags table, or nil if there are no more in the list."
                        (concat "No tags table in use!  "
                                "Use \\[visit-tags-table] to select one.")))))
 
-          (visit-tags-table-buffer-cont
+          ((eq t visit-tags-table-buffer-cont)
            ;; Find the next table.
            (if (tags-next-table)
                ;; Skip over nonexistent files.
@@ -451,6 +455,10 @@ Returns t if it visits a tags table, or nil if there are no more in the list."
            ;; Pick a table out of our hat.
            (setq tags-file-name
                  (or
+                  ;; If passed a string, use that.
+                  (if (stringp visit-tags-table-buffer-cont)
+                      (prog1 visit-tags-table-buffer-cont
+                        (setq visit-tags-table-buffer-cont nil)))
                   ;; First, try a local variable.
                   (cdr (assq 'tags-file-name (buffer-local-variables)))
                   ;; Second, try a user-specified function to guess.
@@ -461,16 +469,19 @@ Returns t if it visits a tags table, or nil if there are no more in the list."
                   ;; If one is found, the lists will be frobnicated,
                   ;; and VISIT-TAGS-TABLE-BUFFER-CONT
                   ;; will be set non-nil so we don't do it below.
-                  (car (or 
-                        ;; First check only tables already in buffers.
-                        (save-excursion (tags-table-including buffer-file-name
-                                                              tags-table-list
-                                                              t))
-                        ;; Since that didn't find any, now do the
-                        ;; expensive version: reading new files.
-                        (save-excursion (tags-table-including buffer-file-name
-                                                              tags-table-list
-                                                              nil))))
+                  (and buffer-file-name
+                       (car (or 
+                             ;; First check only tables already in buffers.
+                             (save-excursion
+                               (tags-table-including buffer-file-name
+                                                     tags-table-list
+                                                     t))
+                             ;; Since that didn't find any, now do the
+                             ;; expensive version: reading new files.
+                             (save-excursion
+                               (tags-table-including buffer-file-name
+                                                     tags-table-list
+                                                     nil)))))
                   ;; Fourth, use the user variable tags-file-name, if it is
                   ;; not already in tags-table-list.
                   (and tags-file-name