Merge branch 'emacs-25-merge'

[gnu-emacs] / lisp / progmodes / xref.el

diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 7e3b5600f1a17d07481896ce310e208c023fa2c9..abb9cc6361dfd5382046670e9c8ce176e664b9dc 100644 (file)
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -201,20 +201,22 @@ LENGTH is the match length, in characters."
 \f
 ;;; API
 
-;; We make the etags backend the default for now, until something
-;; better comes along.
-(defvar xref-backend-functions (list #'xref--etags-backend)
+(defvar xref-backend-functions nil
   "Special hook to find the xref backend for the current context.
 Each functions on this hook is called in turn with no arguments
 and should return either nil to mean that it is not applicable,
 or an xref backend, which is a value to be used to dispatch the
 generic functions.")
 
+;; We make the etags backend the default for now, until something
+;; better comes along.  Use APPEND so that any `add-hook' calls made
+;; before this package is loaded put new items before this one.
+(add-hook 'xref-backend-functions #'etags--xref-backend t)
+
+;;;###autoload
 (defun xref-find-backend ()
   (run-hook-with-args-until-success 'xref-backend-functions))
 
-(defun xref--etags-backend () 'etags)
-
 (cl-defgeneric xref-backend-definitions (backend identifier)
   "Find definitions of IDENTIFIER.
 
@@ -230,10 +232,21 @@ IDENTIFIER can be any string returned by
 
 To create an xref object, call `xref-make'.")
 
-(cl-defgeneric xref-backend-references (backend identifier)
+(cl-defgeneric xref-backend-references (_backend identifier)
   "Find references of IDENTIFIER.
 The result must be a list of xref objects.  If no references can
-be found, return nil.")
+be found, return nil.
+
+The default implementation uses `semantic-symref-tool-alist' to
+find a search tool; by default, this uses \"find | grep\" in the
+`project-current' roots."
+  (cl-mapcan
+   (lambda (dir)
+     (xref-collect-references identifier dir))
+   (let ((pr (project-current t)))
+     (append
+      (project-roots pr)
+      (project-external-roots pr)))))
 
 (cl-defgeneric xref-backend-apropos (backend pattern)
   "Find all symbols that match PATTERN.
@@ -873,7 +886,7 @@ IGNORES is a list of glob patterns."
               hits)))
     (unwind-protect
         (cl-mapcan (lambda (hit) (xref--collect-matches hit regexp))
-                   (nreverse hits))
+                   hits)
       ;; TODO: Same as above.
       (mapc #'kill-buffer
             (cl-set-difference (buffer-list) orig-buffers)))))