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Date: Sun, 18 Jan 2015 19:27:23 +0100
From: Felix Janda <felix.janda@...teo.de>
To: musl@...ts.openwall.com
Subject: Re: getopt_long_only and slightly unambiguous options

Rich Felker wrote:
> On Sun, Jan 18, 2015 at 06:51:59PM +0100, Felix Janda wrote:
> > Hello,
> > 
> > since widl from wine uses the combination, get_opt_long_only seems to
> > be supposed to be able to differentiate between a short option "-h"
> > and a long option "--help". Together with the possibility of option
> > abbreviations, the behavior we are trying to copy is:
> > 
> > -h     -> -h
> > --help -> --help
> > -help  -> --help
> > -he    -> --help
> > --h    -> --help
> > 
> > However musl maps all of them to --help.
> > 
> > The man page is ambiguous about this aspect and I'm not sure if the
> > BSDs have the same behavior here. (However I would suspect that the
> > breakage in widl, when the --help option was added in 2012, would
> > have been noticed.) As always, it is hard to measure how many
> > applications (and scripts written against these applications) might
> > depend on this behavior. Since getopt_long_only is discouraged
> > maybe these are actually quite few, though.
> > 
> > All in all I think that this a bug in musl which should be fixed.
> > 
> > 
> > For the implementation, is it maybe enough in __getopt_long_core to
> > pass options starting with '-' and of exactly two characters
> > directly to getopt?
> 
> I would think getopt_long_only would even want to treat "-he" as "-h"
> and "-e", i.e. abbreviations should be suppressed entirely when only a
> single leading "-" appears instead of "--". However I'd rather follow
> historical practice unless it's something stupid and complex (and
> violating the principle of least surprise for users) like checking
> whether each char is a valid short option and basing the decision on
> that.

I've just checked that even when there are both -h and -e short
options glibc getopt_long_only treats -he as --help.

Felix

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