Re: indirect assignment to array

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

"Sanitizing" a varname for (P) expansion is context-dependent.  For
example, this is "legal":

varname='x[$(echo 3)]'
: ${(AP)varname::=foo}

The point being, there's no straightforward internal test that zsh
could apply to ${(P)varname} that would correctly reject "unsanitary"
references.  I suppose we could do something similar to Perl's taint
checks and prevent (P) from being used on environment variables that
have not been (re)assigned since the current shell started up.