You are partly right about the implementation coverage. For a lot of embedded development where you can't cross compile with a modern compiler it's of course an

You are partly right about the implementation coverage. For a lot of embedded development where you can't cross compile with a modern compiler it's of course an issue. For major desktop and mobile platforms, I don't see an issue. Clang has excellent support for the mandatory parts of C11, it's even the default setting (well GNU C11). Given that one can now configure Clang as the frontend for Visual Studio on Windows, the backwardness of Visual studio in regards to modern C standards is no longer an issue as well. For essential features, well if one uses C it's usually to have fine-graded control of memory use and allocation patterns. Then C11 _Alignas, and _Alignof are pretty essential. Yes you can do that with platform/compiler specific macros without C11, but it's nice to be able to avoid that.