D-Programming-Language/dmd — pull request #1213 by 9rnsr (2012-10-24 14:17:59+00:00)
Title: Issue 7019 - implicit constructors are inconsistently allowed

http://d.puremagic.com/issues/show_bug.cgi?id=7019

From the @andralex's [reply ](http://forum.dlang.org/thread/CAFDvkcvvL8GxHQB=Rw9pTm-uxOKzNGVQNDv9w5Os3SkQCc=DLQ@mail.gmail.com#post-50856AB4.8000909:40erdani.com), we can sure that it is an expected feature.