Fix treesit-thing-definition

* lisp/treesit.el (treesit-thing-definition): Don't modify
treesit-thing-settings itself.

diff --git a/lisp/treesit.el b/lisp/treesit.el
index 57521a236e079564fdc70552b8a16a9d8e22a411..c5ca492a837f6741278138c9e9957815494fe5b1 100644 (file)
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -2064,7 +2064,9 @@ If LANGUAGE is nil, return the first definition for THING in
   (if language
       (car (alist-get thing (alist-get language
                                        treesit-thing-settings)))
-    (car (alist-get thing (mapcan #'cdr treesit-thing-settings)))))
+    (car (alist-get thing (mapcan (lambda (entry)
+                                    (copy-tree (cdr entry)))
+                                  treesit-thing-settings)))))
 
 (defalias 'treesit-thing-defined-p 'treesit-thing-definition
   "Return non-nil if THING is defined.")