diff options
Diffstat (limited to 'lisp/emacs-lisp')
| -rw-r--r-- | lisp/emacs-lisp/subr-x.el | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el index 9c8c967ee9c..5a8885c0427 100644 --- a/lisp/emacs-lisp/subr-x.el +++ b/lisp/emacs-lisp/subr-x.el @@ -289,6 +289,18 @@ than this function." (let ((result nil) (result-length 0) (index (if end (1- (length string)) 0))) + ;; FIXME: This implementation, which uses encode-coding-char + ;; to encode the string one character at a time, is in general + ;; incorrect: coding-systems that produce prefix or suffix + ;; bytes, such as ISO-2022-based or UTF-8/16 with BOM, will + ;; produce those bytes for each character, instead of just + ;; once for the entire string. encode-coding-char attempts to + ;; remove those extra bytes at least in some situations, but + ;; it cannot do that in all cases. And in any case, producing + ;; what is supposed to be a UTF-16 or ISO-2022-CN encoded + ;; string which lacks the BOM bytes at the beginning and the + ;; charset designation sequences at the head and tail of the + ;; result will definitely surprise the callers in some cases. (while (let ((encoded (encode-coding-char (aref string index) coding-system))) (and (<= (+ (length encoded) result-length) length) |