Cease using etags as a default Xref backend

diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index eacb2ea8f5cfd114b187215edbc695a17180eb74..abc7d7a3fc7a21770a434ed52350ad2fa8add47f 100644 (file)
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -241,11 +241,6 @@ 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))
@@ -1658,34 +1653,23 @@ The meanings of both arguments are the same as documented in
         (memq command xref-prompt-for-identifier))))
 
 (defun xref--read-identifier (prompt)
-  "Return the identifier at point or read it from the minibuffer."
-  (let* ((backend (xref-find-backend))
-         (def (xref-backend-identifier-at-point backend))
-         (completion-ignore-case
-          (xref-backend-identifier-completion-ignore-case backend)))
-    (cond ((or current-prefix-arg
-               (not def)
-               (xref--prompt-p this-command))
-           (let ((id
-                  (completing-read
-                   ;; `format-prompt' is new in Emacs 28.1
-                   (if (fboundp 'format-prompt)
-                       (format-prompt (substring prompt 0 (string-match
-                                                           "[ :]+\\'" prompt))
-                                      def)
-                     (if def
-                         (format "%s (default %s): "
-                                 (substring prompt 0 (string-match
-                                                      "[ :]+\\'" prompt))
-                                 def)
-                       prompt))
-                   (xref-backend-identifier-completion-table backend)
-                   nil nil nil
-                   'xref--read-identifier-history def t)))
-             (if (equal id "")
-                 (or def (user-error "No default identifier"))
-               id)))
-          (t def))))
+  "Return the identifier at point or prompt for it with PROMPT."
+  (if-let* ((backend (xref-find-backend)))
+      (let ((def (xref-backend-identifier-at-point backend))
+            (completion-ignore-case
+             (xref-backend-identifier-completion-ignore-case backend)))
+        (cond ((or current-prefix-arg (not def) (xref--prompt-p this-command))
+               (let ((id
+                      (completing-read
+                       (format-prompt prompt def)
+                       (xref-backend-identifier-completion-table backend)
+                       nil nil nil
+                       'xref--read-identifier-history def t)))
+                 (if (string-empty-p id)
+                     (user-error "You didn't specify an identifier")
+                   id)))
+              (t def)))
+    (user-error "No Xref backend available")))
 
 \f
 ;;; Commands
@@ -1740,7 +1724,7 @@ The fetcher function returns a list of xrefs, and sets
 
 It revisits the saved position and delegates the finding logic to
 the xref backend method indicated by KIND and passes ARG to it."
-  (xref-make-fetcher (xref-find-backend)
+  (xref-make-fetcher (or (xref-find-backend) (error "No Xref backend found"))
                      input kind arg
                      (current-buffer)
                      (copy-marker (point))))
@@ -1760,19 +1744,19 @@ Otherwise, display the list of the possible definitions in a
 buffer where the user can select from the list.
 
 Use \\[xref-go-back] to return back to where you invoked this command."
-  (interactive (list (xref--read-identifier "Find definitions of: ")))
+  (interactive (list (xref--read-identifier "Find definitions of")))
   (xref--find-definitions identifier nil))
 
 ;;;###autoload
 (defun xref-find-definitions-other-window (identifier)
   "Like `xref-find-definitions' but switch to the other window."
-  (interactive (list (xref--read-identifier "Find definitions of: ")))
+  (interactive (list (xref--read-identifier "Find definitions of")))
   (xref--find-definitions identifier 'window))
 
 ;;;###autoload
 (defun xref-find-definitions-other-frame (identifier)
   "Like `xref-find-definitions' but switch to the other frame."
-  (interactive (list (xref--read-identifier "Find definitions of: ")))
+  (interactive (list (xref--read-identifier "Find definitions of")))
   (xref--find-definitions identifier 'frame))
 
 ;;;###autoload
@@ -1783,7 +1767,7 @@ offering the symbol at point as the default.
 With prefix argument, or if `xref-prompt-for-identifier' is t,
 always prompt for the identifier.  If `xref-prompt-for-identifier'
 is nil, prompt only if there's no usable symbol at point."
-  (interactive (list (xref--read-identifier "Find references of: ")))
+  (interactive (list (xref--read-identifier "Find references of")))
   (xref--find-xrefs identifier 'references identifier nil))
 
 (defun xref-find-references-and-replace (from to)
@@ -1846,15 +1830,7 @@ output of this command when the backend is etags."
                       (xref-backend-identifier-at-point
                        (xref-find-backend)))))
   (require 'apropos)
-  (let* ((newpat
-          (if (and (version< emacs-version "28.0.50")
-                   (memq (xref-find-backend) '(elisp etags)))
-              ;; Handle backends in older Emacs.
-              (xref-apropos-regexp pattern)
-            ;; Delegate pattern handling to the backend fully.
-            ;; The old way didn't work for "external" backends.
-            pattern)))
-    (xref--find-xrefs pattern 'apropos newpat nil)))
+  (xref--find-xrefs pattern 'apropos pattern nil))
 
 (defun xref-apropos-regexp (pattern)
   "Return an Emacs regexp from PATTERN similar to `apropos'."