In C11 there is type generic macros that helps writing C++-like overloaded functions.
There are several extensions in GCC too.
For RAII-like memory management, there are __attribute__((constructor)) and __attribute__((destructor)).
C++ does type reflection on constant expressions via type traits templates, in GCC there is simply typeof().
If you are bored about writing static function modifiers, you can write a function inside function.
If you want to allocate a vector which won't change capacity and be released when out of local scope , for example in C++:
auto v = std::vector<int>(n);
int v[n]; // n is a variable determined at runtime