Backslash missing in brace expansion

[Martin Schulte]

Hello,

please have a look:

$ uname -a
Linux martnix4 4.9.0-11-amd64 #1 SMP Debian 4.9.189-3+deb9u2 (2019-11-11)
x86_64 GNU/Linux $ echo ${BASH_VERSINFO[@]}
4 4 12 1 release x86_64-pc-linux-gnu
$ set -x
$ echo {Z..a}
+ echo Z '[' '' ']' '^' _ '`' a
Z [  ] ^ _ ` a

It looks as if the backslash (between [ and ] in ASCII code) is missing in
brace expansion. The same behaviour seems to be found in bash 5.0.

Best regards,

Martin