mozilla/rust — pull request #12791 by alexcrichton (2014-03-09 21:12:53+00:00)
Title: Extract logging to a separate crate

The rationale and modifications can be found in the first commit message.

This does make logging a bit more painful to use initially because it involves a feature gate and some `phase` attributes, but I think it may be reasonable to not require the `phase` attribute for loading `macro_rules!` macros because defining them will still be gated.