Completiong for first word invoked even when cursor is before the first word

[Ville Skyttä]

Hello,

Completion functions seem to be invoked for the first word even when the
cursor is before that word.  For example:

$ foo() { echo ; echo completing; }
$ foo # hit Ctrl-A to go to beginning of line (before foo), then Tab
completing

Same thing if there's whitespace before the first word and cursor is
somewhere there in the whitespace.  Is this on purpose?

I find that behavior unexpected and I suppose this is a case that is
awkward to handle in completion functions and I'm not aware of any
functions "out there" that would handle it.  I'd expect either the empty
completion or no completions at all in that case.