Re: Global variable modification by nameref chain

[Dan Douglas]

How about just doing it similar to the way mksh resolves arithmetic
variable loops? As each variable is visited, add it to a list (or hash
set) and check whether that node was already visited. That should work
without having to consider scope issues.

$ mksh -c 'a=b b=c c=d d=1; echo $((a))'
1
$ mksh -c 'a=b b=c c=d d=a; echo $((a))'
mksh: a: expression recurses on parameter 'a'

This nicely says which variable was to blame. I've noticed bash devel
right now can give messages about "invalid identifiers" which are
technically valid in most contexts so it's tough to track down
problems in complicated reference chains.