ksh93: shell quoting within glob bracket patterns has no effect

[McDutchie]

This bug means the - retains it special meaning of 'character range', and an initial ! (or ^) retains the meaning of negation, even in quoted strings within bracket patterns, including quoted variables.

for var in 'a-c' '!a'; do
	case b in
	( ["$var"] )	echo 'bug' ;;
	( [$var] )	echo 'no bug' ;;
	esac
done

Output: bug (twice)

[Is this actually a bug, or just a quirk/minority behaviour? ksh93, older zsh, and bosh (schilytools Bourne shell) are the only ones to act this way, but I can't find a relevant POSIX text now. But in any case, quoting * and ? in case glob patterns always works to disable their behaviour as wildcards, so it seems inconsistent at best for the same sort of quoting to be ignored in glob bracket patterns.]

[siteshwar]

This will be a backward incompatible change and I would like to avoid such changes unless there is really good reason for it. Looks like not a bug to me.

[McDutchie]

I've now asked for clarification on the Austin Group mailing list. Please follow that thread, particularly this response from Geoff Clare which gives a strong reason why this is a bug.