D-Programming-Language/dmd — pull request #3364 by WalterBright (2014-03-07 09:58:41+00:00)
Title: DIP29: make dup functions pure

This adds attributes pure, nothrow, and @trusted to the .dup internal function.

It also allows for better unique detection on the arguments to adDup(). For example, `adDup(null)` should be implicitly convertible.