DMD 2.059 is now available in the "sunrise" overlay. It took a little longer, but includes fixes for the regressions that occurred shortly after the initial release:

- move the import of onOutOfMemoryError out of the deprecated section
  https://github.com/D-Programming-Language/phobos/commit/55d89dcad1629a2a1a9165ffd5a91aee588fd8a1

- sep (deprecated) -> dirSeparator
  https://github.com/D-Programming-Language/phobos/commit/dfe83f155d92c98e08b9c896f6312d96794b39f9

- Issue 7907 - [ICE] invalid expression on template argument crashes dmd
  https://github.com/D-Programming-Language/dmd/pull/879

- Issue 7911 - Nested static if failing to execute
  http://d.puremagic.com/issues/show_bug.cgi?id=7911

- Issue 7922 - alias this causes weird formatting issues for strings
  https://github.com/D-Programming-Language/dmd/pull/885

So it should be safe to upgrade on Gentoo now.

-- 
Marco