[BUG] derived-mode-merge-syntax-tables bugs out in Gnus/Message

Recently following a Debian update I found I was unable to reply to articles in Gnus; I got an error along the lines of: Args out of range: " .w_()'\"$\\/<>＠!|", 64 It turns out that this message comes from derived-mode, more specifically from derived-mode-merge-syntax-tables. That function does something like: (when (eq ?＠ (char-syntax-from-code (get-range-char-table key new ?＠))) ...) The obvious intention is: "get key from range-table, or ?＠ if not found". But char-syntax-from-code can't cope with ?＠, it expects a small number that is a valid offset in the string. When it receives ?＠ (or 64), it signals "Args out of range". In case it matters, the KEY for which the error occurs is the symbol `latin-iso8859-13'. (Perhaps the Debian upgrade introduced this charset to my XEmacs?) Inspection revealed that ＠ happens to be at position 13 of the string in question. Following that lead, I made this modification: (when (eq ?＠ (char-syntax-from-code (get-range-char-table key new 13))) ...) which removes the error for me. But this is clearly not the right fix because it relies on a cryptic offset into an unrelated string. It should probably be modified to this: (when (let ((tmpcode (get-range-char-table key new 'multi))) (or (eq tmpcode 'multi) (eq (char-syntax-from-code tmpcode) ?＠))) ...) or to equivalent but more elegant code that I currently don't seem to be able to write. Someone with a better understanding of the code in question and of syntax tables in general might come up with a better fix.