Auto merge of #4343 - sid0:debug, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 31 Jul 2017 19:13:35 +0000 (19:13 +0000)
committerbors <bors@rust-lang.org>
Mon, 31 Jul 2017 19:13:35 +0000 (19:13 +0000)
derive/impl Debug for a few data structures

I found this to be extremely useful while trying to write a wrapper on
top of cargo.


Trivial merge