Add completion for cargo.

[NariyasuHeseri]

No description provided.

[cornfeedhobo]

Thanks for your contribution! I've left some comments for things to change.

My last question is if this is your own creation or copied from an upstream source? If you have copied it, could you please include a comment at the top of the file linking to the original source and giving them credit.

Thanks!

[NariyasuHeseri]

ShellCheck reports SC2207 warnings but this seems to lead to cumbersome "while read line" statements to fix them.
Sould we disable SC2207 rule?

[NoahGorny]

@NariyasuHeseri I am not convinced that copying completion files is the correct solution here.. seems like rust-lang/rustup#1646 caused rustup to add cargo completion. We can enhance the newly added rustup completion file to also autocomplete cargo

[NariyasuHeseri]

I have finnaly figured out eval "$(rustup completions bash cargo)" can be used to add completion for cargo.
I'm going to close this PR. Thank you.

[cornfeedhobo]

@NariyasuHeseri Oh good digging! If you feel like re-opening this PR, what you found would be great to codify. Something like...

if _command_exists rustup ; then
	eval "$(rustup completions bash cargo)"
fi

Otherwise I might get around to it when I start playing with rust. Thanks again!

[NariyasuHeseri]

I have opened a new PR adding these lines in cargo.completion.bash (to make commit histories cleaner).