There seems to be a bug that if an array variable with a name matching one
of the special single-character variables exists, then that variable is
used during substring expansion and parameter transformation.
There is also a potential issue with namerefs, in that they allow
creating/modifying variables with invalid identifiers if a variable is
defined first and subsequently given the nameref attribute, which is how
the above behavior can be uncovered.
# Expected behavior:set -- 1 2 3echo ${@@A} # set -- '1' '2'
'3'echo ${@:0} # bash 1 2 3
ref=@declare -n ref # maybe should not be allowed?
ref=(X)
# These no longer reference the positional parameters:echo ${@@A}
# declare -a @='X'echo ${@:0} # X
