rust-lang/cargo — pull request #682 by vhbit (2014-10-08 06:01:01+00:00)
Title: Allow to invoke Cargo commands with empty features

For automation it should be no difference between invocations
of `--features "feat1 feat2 feat3"` and `--features ""`.

The problem is that in the latter case `docopt` sets flag_feature to vec![""]

Could be solved on 3 different levels:

- patching `docopt` to treat empty string for a Vec flag
as empty vec. Although I can't imagine that in some place it
might be required to treat empty string as vector of empty
strings it is might have its own use

- filtering flags_feature right after parsing command line and
before passing further. It means it should be fixed in at
least 4 different places now and may be forgotten in future

- filtering empty string feature while resolving - perhaps
the easiest and more universal solution, implemented in this
patch