${#a#a} bug?

[Vladimir N. Oleynik]

Hello.

$ a=abc
$ echo ${#a#a}

dash-0.5.11.3 produce:
3a
bash:
${#a#a}: bad substitution


Also, found incompatibility vs bash, may be is not bug:
for ${#*} bash eq $#, dash - s="$*" ${#s} :)


--w
vodz