invalid characters and multi-byte [x-y] ranges

[Stephane Chazelas <stephane.chazelas@gmail.com>]

Hello,

is this (in a UTF-8 locale):

$ zsh -c $'[[ \xcc = [\uaa-\udd] ]]' && echo yes
yes

expected or desirable? I know I can't expect much since \xcc is
not a valid character, but I wouldn't have expected it to match
[\uaa-\udd] there.

Same for:

$ zsh -c $'[[ \xcc = [[:alpha:]] ]]' && echo yes
yes

It seems \xcc is treated as U+00CC here (which in UTF-8 is
\xc3\x8c)

$ zsh -c $'[[ \xcc = \ucc ]]' && echo yes
$ zsh -c $'[[ \xcc = [\ucc] ]]' && echo yes
yes

-- 
Stephane