I appreciate rust as much as the next dev. But you can define your own types in C just as well? And with the proper warnings and errors -Wall -Werror in place, any warning is an error, and implicit conversions should probably be a warning right?

ETA: Just tried with the following C code and could not get it to fail with gcc.

typedef int t_0;
typedef long t_1;

t_0 test() {
  t_1 foo = 1;
  return foo;
}

Tried with gcc -Wall -Wextra -Wpedantic -Werror and it compiled just fine.