How do I build gcc with C++ concepts (“concepts lite”) support?

Question

The C++ standards committee is working on a TS (Technical Specification) for Concepts extension: \"Programming Languages - C++ Extensions for Concepts\". N4377 is the latest

Answer 1

As of Fri, 7 Aug 2015 01:44:49 -0400 (05:44 +0000) concepts support has been merged into gcc's trunk.

Using a build from after that point, you can enable concepts support with the -std=c++1z flag.

As of gcc 6.1 (27-04-2016), concepts are enabled by -fconcepts as they are unlikely to be included in C++17, so they have been removed from -std=c++1z. (via @BruceAdams in comments below)