Collating Symbol `[.` `.]` Error

[e-kwsm]

revision: 628d320

For instance, Hungarian has a trigraph dzs and digraphs such as cs, dz, and so forth.

uutils does not raise error when a collation character is invalid:

$ export LANG=en_US.UTF-8
$ <<< dzs gnused -e 's/[[.dzs.]]/@/'
gnused: -e expression #1, char 14: Invalid collation character
$ <<< dzs bsdsed -e 's/[[.dzs.]]/@/'
bsdsed: 1: "s/[[.dzs.]]/@/
": RE error: Invalid collation character
$ <<< dzs ./target/debug/sed -e 's/[[.dzs.]]/@/'
@zs

$ <<< x ./target/debug/sed -e 's/[[.ThisMustBeInvalid.]]/@/'
@

and does not properly handle it under Hungarian:

$ export LANG=hu_HU.UTF-8
$ <<< dzs gnused -e 's/[[.dzs.]]/@/'
@
$ <<< dzs bsdsed -e 's/[[.dzs.]]/@/'
@
$ <<< dzs ./target/debug/sed -e 's/[[.dzs.]]/@/'
@zs

https://pubs.opengroup.org/onlinepubs/7908799/xbd/re.html#tag_007_003_005