VLAs were made optional in C11 and no longer required for ISO C compliance.
Google also sponsored the work to clean up the Linux kernel of their use.
I wish they removed trigraphs. They are removed from C++ since C++17. I hope they do that in a future C standard as well. Currently I switch to std=gnuXX in GCC solely for this reason (and sometimes to get access to some POSIX headers).
Is there any code that still uses them? I've never seen trigraphs in the wild.
I knew about defined size ints (use them a lot in osdev) and _Bool (you don't have stdbool everywhere)