When trying to compile some test code with the latest git versions of DMD2/Phobos as of now, i get the error: std\regex.d(2841): Error: undefined identifier writefln adding a local import of std.stdio inside the dump() function (line 2838) seems to fix it.
https://github.com/D-Programming-Language/phobos/pull/329
https://github.com/D-Programming-Language/phobos/commit/cce4ad277b0556b4d30e75c4a96e23a4128b2a5b