I know the answer is 99.99% no, but I figured it was worth a try, you never know.
void SomeFunction(int a)
{
// Here some processing happens on a, for ex
I don't actually suggest doing this, but you could use creative variable shadowing to simulate something like what you want:
void SomeFunction(int a)
{
// Here some processing happens on a, for example:
a *= 50;
a %= 10;
if(example())
a = 0;
{
const int b = a;
const int a = b; // New a, shadows the outside one.
// Do whatever you want inside these nested braces, "a" is now const.
}
}