Negative COMP_CWORD values?

[Ville Skyttä]

Hello,

Is it intentional that COMP_CWORD may have a negative value within a 
completion function?  I did not find any indication of that in the bash man 
page.  For example:

    foo()
    {
            echo "COMP_CWORD:$COMP_CWORD"
    }
    complete -F foo bar

Then, type "bar  " (sans quotes, two spaces), go back between the two spaces 
and hit tab.  All bash versions I've tried with (various 3.x and 4.0 ones) 
print out COMP_CWORD:-2.  The -2 will obviously not work too well with things 
like ${COMP_WORDS[COMP_CWORD]} (bad array subscript).

Please Cc me in replies, I'm not subscribed to bug-bash at the moment.