An evolution of gcc occured:

C++ concepts support merged into gcc trunk

From the article:

I've been banging on the concepts branch for the past month after Andrew told me it was about ready to merge, fixing bugs and streamlining things there to get familiar with the code while I could still look at it as a whole rather than mixed in with the rest of the compiler. But I think I've reached diminishing returns and so I'm going to go ahead and merge it into the trunk...