Don’t attempt to modify constant conses

From a patch privately suggested by Mattias Engdegård on 2020-05-11
in a followup to Bug#40671.
* admin/charsets/cp51932.awk:
* admin/charsets/eucjp-ms.awk:
Generate code that does not modify constant conses.
* doc/misc/emacs-mime.texi (Encoding Customization):
* lisp/emacs-lisp/byte-opt.el (byte-compile-side-effect-free-ops):
* lisp/frameset.el (frameset-persistent-filter-alist):
* lisp/gnus/gnus-sum.el (gnus-article-mode-line-format-alist):
Use append instead of nconc.
* lisp/language/japanese.el (japanese-ucs-cp932-to-jis-map)
(jisx0213-to-unicode):
Use mapcar instead of mapc.
* lisp/language/lao-util.el (lao-transcription-consonant-alist)
(lao-transcription-vowel-alist):
* lisp/language/tibetan.el (tibetan-subjoined-transcription-alist):
Use copy-sequence.
* test/src/fns-tests.el (fns-tests-nreverse):
(fns-tests-sort, fns-tests-collate-sort)
(fns-tests-string-version-lessp, fns-tests-mapcan):
Use copy-sequence, vector, and list.

6 files changed, 30 insertions, 24 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 4f72251aed5..62b82e4f32a 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -1509,7 +1509,7 @@
     byte-current-buffer byte-stack-ref))
 
 (defconst byte-compile-side-effect-free-ops
-  (nconc
+  (append
    '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
      byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
      byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
diff --git a/lisp/frameset.el b/lisp/frameset.el
index 10c6914f52d..0462d776c0e 100644
--- a/lisp/frameset.el
+++ b/lisp/frameset.el
@@ -396,17 +396,17 @@ Properties can be set with
 ;; or, if you're only changing a few items,
 ;;
 ;;   (defvar my-filter-alist
-;;     (nconc '((my-param1 . :never)
-;;              (my-param2 . my-filtering-function))
-;;            frameset-filter-alist)
+;;     (append '((my-param1 . :never)
+;;               (my-param2 . my-filtering-function))
+;;             frameset-filter-alist)
 ;;     "My brief customized parameter filter alist.")
 ;;
 ;; and pass it to the FILTER arg of the save/restore functions,
 ;; ALWAYS taking care of not modifying the original lists; if you're
 ;; going to do any modifying of my-filter-alist, please use
 ;;
-;;   (nconc '((my-param1 . :never) ...)
-;;          (copy-sequence frameset-filter-alist))
+;;   (append '((my-param1 . :never) ...)
+;;           (copy-sequence frameset-filter-alist))
 ;;
 ;; One thing you shouldn't forget is that they are alists, so searching
 ;; in them is sequential.  If you just want to change the default of
@@ -445,7 +445,7 @@ DO NOT MODIFY.  See `frameset-filter-alist' for a full description.")
 
 ;;;###autoload
 (defvar frameset-persistent-filter-alist
-  (nconc
+  (append
    '((background-color            . frameset-filter-sanitize-color)
      (buffer-list                 . :never)
      (buffer-predicate            . :never)
diff --git a/lisp/gnus/gnus-sum.el b/lisp/gnus/gnus-sum.el
index 6f367692ddd..341f04ad772 100644
--- a/lisp/gnus/gnus-sum.el
+++ b/lisp/gnus/gnus-sum.el
@@ -1501,9 +1501,9 @@ the type of the variable (string, integer, character, etc).")
 
 ;; This is here rather than in gnus-art for compilation reasons.
 (defvar gnus-article-mode-line-format-alist
-  (nconc '((?w (gnus-article-wash-status) ?s)
-           (?m (gnus-article-mime-part-status) ?s))
-         gnus-summary-mode-line-format-alist))
+  (append '((?w (gnus-article-wash-status) ?s)
+            (?m (gnus-article-mime-part-status) ?s))
+          gnus-summary-mode-line-format-alist))
 
 (defvar gnus-last-search-regexp nil
   "Default regexp for article search command.")
diff --git a/lisp/language/japanese.el b/lisp/language/japanese.el
index d77efa48c9b..9a99245dfde 100644
--- a/lisp/language/japanese.el
+++ b/lisp/language/japanese.el
@@ -82,9 +82,7 @@
          (#x00A6 . #xFFE4)      ; BROKEN LINE           FULLWIDTH BROKEN LINE
          )))
   (define-translation-table 'japanese-ucs-jis-to-cp932-map map)
-  (mapc #'(lambda (x) (let ((tmp (car x)))
-                        (setcar x (cdr x)) (setcdr x tmp)))
-        map)
+  (setq map (mapcar (lambda (x) (cons (cdr x) (car x))) map))
   (define-translation-table 'japanese-ucs-cp932-to-jis-map map))
 
 ;; U+2014 (EM DASH) vs U+2015 (HORIZONTAL BAR)
@@ -241,8 +239,10 @@ eucJP-ms is defined in <http://www.opengroup.or.jp/jvc/cde/appendix.html>."
          (#x2b65 . [#x02E9 #x02E5])
          (#x2b66 . [#x02E5 #x02E9])))
       table)
-  (dolist (elt map)
-    (setcar elt (decode-char 'japanese-jisx0213-1 (car elt))))
+  (setq map
+        (mapcar (lambda (x) (cons (decode-char 'japanese-jisx0213-1 (car x))
+                                  (cdr x)))
+                map))
   (setq table (make-translation-table-from-alist map))
   (define-translation-table 'jisx0213-to-unicode table)
   (define-translation-table 'unicode-to-jisx0213
diff --git a/lisp/language/lao-util.el b/lisp/language/lao-util.el
index a20aecee421..fa4c2f7f891 100644
--- a/lisp/language/lao-util.el
+++ b/lisp/language/lao-util.el
@@ -183,7 +183,9 @@
 ;; Semi-vowel-sign-lo and lower vowels are put under the letter.
 
 (defconst lao-transcription-consonant-alist
-  (sort '(;; single consonants
+  (sort
+   (copy-sequence
+        '(;; single consonants
           ("k" . "ກ")
           ("kh" . "ຂ")
           ("qh" . "ຄ")
@@ -223,14 +225,16 @@
           ("hy" . ["ຫຍ"])
           ("hn" . ["ຫນ"])
           ("hm" . ["ຫມ"])
-          )
-        (function (lambda (x y) (> (length (car x)) (length (car y)))))))
+          ))
+   (lambda (x y) (> (length (car x)) (length (car y))))))
 
 (defconst lao-transcription-semi-vowel-alist
   '(("r" . "ຼ")))
 
 (defconst lao-transcription-vowel-alist
-  (sort '(("a" . "ະ")
+  (sort
+   (copy-sequence
+        '(("a" . "ະ")
           ("ar" . "າ")
           ("i" . "ິ")
           ("ii" . "ີ")
@@ -257,8 +261,8 @@
           ("ai" . "ໄ")
           ("ei" . "ໃ")
           ("ao" . ["ເົາ"])
-          ("aM" . "ຳ"))
-        (function (lambda (x y) (> (length (car x)) (length (car y)))))))
+          ("aM" . "ຳ")))
+   (lambda (x y) (> (length (car x)) (length (car y))))))
 
 ;; Maa-sakod is put at the tail.
 (defconst lao-transcription-maa-sakod-alist
diff --git a/lisp/language/tibetan.el b/lisp/language/tibetan.el
index d31cd5cd528..bbd4729f6c5 100644
--- a/lisp/language/tibetan.el
+++ b/lisp/language/tibetan.el
@@ -326,7 +326,9 @@
 
 
 (defconst tibetan-subjoined-transcription-alist
-  (sort '(("+k"  . "ྐ")
+  (sort
+   (copy-sequence
+        '(("+k"  . "ྐ")
           ("+kh" . "ྑ")
           ("+g"  . "ྒ")
           ("+gh" . "ྒྷ")
@@ -371,8 +373,8 @@
           ("+W" . "ྺ") ;; fixed form subscribed WA
           ("+Y" . "ྻ") ;; fixed form subscribed YA
           ("+R" . "ྼ") ;; fixed form subscribed RA
-          )
-        (lambda (x y) (> (length (car x)) (length (car y))))))
+          ))
+   (lambda (x y) (> (length (car x)) (length (car y))))))
 
 ;;;
 ;;; alist for Tibetan base consonant <-> subjoined consonant conversion.