Highlight xref matches in the target buffer more accurately

Use `xref-make-match` in Emacs 28; it takes a length argument.

Author: mattiase

emacs/merlin-xref.el

@@ -16,9 +16,15 @@
 (cl-defmethod xref-backend-references ((_backend (eql merlin-xref)) symbol)
   (mapcar
    (lambda (loc)
-     (let ((pt (merlin-make-point (alist-get 'start loc))))
-       (xref-make (merlin-xref--line pt)
-                  (xref-make-buffer-location (current-buffer) pt))))
+     (let* ((pt (merlin-make-point (alist-get 'start loc)))
+            (summary (merlin-xref--line pt))
+            (location (xref-make-buffer-location (current-buffer) pt)))
+       (if (>= emacs-major-version 28)
+           ;; `xref-make-match' doesn't accept `xref-buffer-location'
+           ;; arguments until Emacs 28.
+           (let ((length (- (merlin-make-point (alist-get 'end loc)) pt)))
+             (xref-make-match summary location length))
+         (xref-make summary location))))
    (save-excursion
      (let ((pt (get-text-property 0 'merlin-xref-point symbol)))
        (when pt