ISO C is increasingly moronic
Doesn't seem like the author really thought some of this through:FTA: "The  file according to the standard shall have exactly this content: "#define noreturn _Noreturn" Are you crying or laughing yet ?"It's a compatibility constraint.  They can't simply add new reserved words to the language because it will break preexisting code (c.f. all the old C headers with idenfiers like "bool" or "class" or "virtual" that don't build in C++).  The underscore-followed-by-capital convention happened to have been reserved by ISO C90, so that's what they picked.But they allow that this is ugly, so there's a new C1X header file you can include in new C1X code that makes the identifiers look like you expect they should.  Obviously old code won't include this header and is insulated from the change.  (I guess if you wanted to nit here, having a separate header for each new feature seems dumb to me.  Why not a single  or the like?)Compatibility is important, especially for languages like C with staggeringly large bases of mature code.  For an example of what happens when you break compatibility in the name of "progress" see Python3, which years on is still not installed by default anywhere, and probably never will be.