[kats]

It has a lot of costs to add to the C language, even if it's just the increased complexity in the documentation, and doesn't effect c99. Every processor, OS, programming language needs used in business needs to fully support a C standard. So adding to C effects every processor and computer architecture, every new OS, every new language.

If you look at CPPreference you can see how much complexity has been added to the C standard in the last few years.

[dale_glass]

What do those have to do with that? A processor has no need to know anything about constexpr, auto, or static_assert.

In fact I don't see anything that needs support anywhere but the actual compiler.