This patch is a tweak of changyu's patch: https://reviews.llvm.org/D40381. It differs in that the recognition of the 'concept' token is moved into the machinery that recognizes declaration-specifiers - this allows us to leverage the attribute handling machinery more seamlessly.
See the test file to get a sense of the basic parsing that this patch supports.
There is much more work to be done before concepts are usable...
Thanks Changyu!
llvm-svn: 330794
Faisal Vali