You mean something like "unsigned short int" :) ? Another example would be "const". What's the point - either the variable is const or it isn't. Programmer can just remove the mutation.
> My undrstanding is that a tail call is a tail call, and the variant with +1 is not that, thus being a candidate to be looked at.
Sure, but don't you agree it's an easy mistake to make? Especially when the recursion goes through several different functions. Additionally - you reading the code might not realize it's important for this function to continue to be tail-recursive.
> Perhaps also IDEs can help here if it's difficult to spot?
Or perhaps a compiler can do it?
