(make-coding-system): Purecopy doc-string.

diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index f8e5e7426a9660866afd25cebb340580623bdfdc..7b32325db464890d53893d0672744cff299d1322 100644 (file)
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -636,7 +636,7 @@ a value of `safe-charsets' in PLIST."
     (aset coding-spec coding-spec-type-idx type)
     (aset coding-spec coding-spec-mnemonic-idx mnemonic)
     (aset coding-spec coding-spec-doc-string-idx
-         (if (stringp doc-string) doc-string ""))
+         (purecopy (if (stringp doc-string) doc-string "")))
     (cond ((= type 0)
           (setq coding-category 'coding-category-emacs-mule))
          ((= type 1)