Re: parse-options: ambiguous LASTARG_DEFAULT and OPTARG

René Scharfe wrote:

PARSE_OPT_OPTARG overrides PARSE_OPT_LASTARG_DEFAULT, as Pierre noted in
commit 1cc6985c, which introduced the latter, so the two should not be
used together.

Ok, thanks. This means I used it wrong when I switched over show-branch
:-/ I'll have to send a follow-up patch for that.

PARSE_OPT_LASTARG_DEFAULT uses the default value if the option is the
last one on the command line and requires an explicit argument if it's
not the last, as you found out above.  That's also what the code says
and its name implies; the comment in parse-options.h (by yours truly)
is probably misleading because it doesn't mention this condition.

I was mislead. When I read it I thought I had to use the flag to say
that the default value will be used in the case when no argument is
given. I completely ignored the LASTARG part (I thought it was
referencing the default arg). I think just adding what you said here to
parse-options.h will help others to avoid this.

I don't remember any other program having options with such a
behaviour; I'm not sure how to stress that --merged needs to be the
last option, as implied by the help message.

"git tag --contains" is the same. Figuring out a way to say that the
syntax changes when it's the last option versus in the middle is not
obvious to me either.