Precision matters, when end pointers are used there is no limit for the string/array size, as it is traditional argument the C folks use against bounds checked data structures.

"C can get new types" is definitly a solution, one where new types can be incremently used and with time transition existing code bases to the new types.

By your own words, "C can get compiler annotations" is not a solution for the problem as well, someone has to write the code that uses those annotions, hardly any different from using new types.