Don’t attempt to modify constant strings

* lisp/bookmark.el (bookmark-bmenu-set-header):
Use copy-sequence instead of concat, for clarity.
Also, the byte-compiler optimizes (concat "a" "b") into "ab".
* lisp/button.el (make-text-button):
* test/lisp/erc/erc-track-tests.el (erc-track--erc-faces-in):
* test/lisp/password-cache-tests.el:
(password-cache-tests-add-and-remove)
(password-cache-tests-read-from-cache)
(password-cache-tests-in-cache-p, password-cache-tests-read)
(password-cache-tests-reset)
(password-cache-tests-add/expires-key)
(password-cache-tests-no-password-cache):
Don’t attempt to modify constant strings.
* lisp/progmodes/elisp-mode.el (elisp--xref-format)
(elisp--xref-format-extra):
Don’t attempt to modify constant strings via put-text-property.
* test/lisp/emacs-lisp/cl-macs-tests.el (cl-macs-loop-across-ref):
Don’t attempt to modify constant vectors or strings.

1 files changed, 3 insertions, 1 deletions

diff --git a/test/lisp/emacs-lisp/cl-macs-tests.el b/test/lisp/emacs-lisp/cl-macs-tests.el
index 983e79ac57c..24bbad0cc6b 100644
--- a/test/lisp/emacs-lisp/cl-macs-tests.el
+++ b/test/lisp/emacs-lisp/cl-macs-tests.el
@@ -425,7 +425,9 @@ collection clause."
                  '(2 3 4 5 6))))
 
 (ert-deftest cl-macs-loop-across-ref ()
-  (should (equal (cl-loop with my-vec = ["one" "two" "three"]
+  (should (equal (cl-loop with my-vec = (vector (cl-copy-seq "one")
+                                                (cl-copy-seq "two")
+                                                (cl-copy-seq "three"))
                           for x across-ref my-vec
                           do (setf (aref x 0) (upcase (aref x 0)))
                           finally return my-vec)