Format whitespace within attributes

[euclio]

I'm not sure if there's a decision on this in the wider Rust community, but I think it'd make sense to format attributes so that attributes are formatted to either

#[cfg(feature="nightly")]

or

#[cfg(feature = "nightly")]

[marcusklaas]

@nrc: do you know if there's enough info in the AST to do this?

[nrc]

I don't know, but in any case I plan to change the representation of attributes pretty soon as part of the macro reform work.

[marcusklaas]

Okay, probably shouldn't touch this yet then.

[killercup]

Just came across this, and would love to see this implemented. Especially when looking at code generated with quote!, attributes look weird (e.g., # [ derive ( Clone , PartialEq , Debug , Deserialize , Serialize ) ]).

I assume the final syntax is defined by rust-lang/style-team#82, but the only outstanding issue seems to be minor (spaces around =).

[nrc]

I don't know, but in any case I plan to change the representation of attributes pretty soon as part of the macro reform work.

This is now done