"${(s.:.)foo} and rc_expand_param

[Frank Terbeck <ft@xxxxxxxxxxxxxxxxxxx>]

Hey list,

Here is another thing I can't quite understand.

First, two excerpts from the manual:

  RC_EXPAND_PARAM (-P)
      Array expansions of the form âfoo${xx}barâ, where the parameter xx
      is set to (a b c), are substituted with âfooabar foobbar foocbarâ
      instead of the default âfooa b cbarâ.
[...]

  s:string:
      Force field splitting at the separator string.  Note that a string
      of two or more characters means that all of them must match in
      sequence; this differs from the treatment of two or more
      characters in the IFS parameter.  See also the = flag and the
      SH_WORD_SPLIT option.

      For historical reasons, the usual behaviour that empty array
      elements are retained inside double quotes is disabled for arrays
      generated by splitting; hence the following:

             line="one::three"
             print -l "${(s.:.)line}"

      produces two lines of output for one and three and elides the
      empty field.  To override this behaviour, supply the "(@)" flag as
      well, i.e.  "${(@s.:.)line}".

Now, let's see what's happening:

zsh% foo="bar::baz"
zsh% print -l "${(s.:.)foo}"
bar
baz

Okay, this I expected, but now:

zsh% setopt rc_expand_param
zsh% print -l "${(s.:.)foo}"
bar

baz

This I did not; from the manual I'd expect to only see (@s.:.) pick up
the empty field in $foo.

Am I missing something here or is this a bug?

Regards, Frank

-- 
In protocol design, perfection has been reached not when there is
nothing left to add, but when there is nothing left to take away.
                                                  -- RFC 1925