mozilla/rust — pull request #12630 by alexcrichton (2014-02-28 20:59:26+00:00)
Title: Make io::stdout() and io::stderr() return buffered writers by default

Now that we can call `flush()` in destructors, I think that it's appropriate for stdout/stderr to return buffered writers by default.

This doesn't enable certain functionality like a buffered stdin does, but it's what you want 90% of the time for performance reasons.