[xfs]

If you as a reader need const to make sure a local variable is not changed this is usually a symptom of this function being too long to see at a glance. And quite often as code changes I do need to make some local variable non-const, and it quickly becomes annoying to fiddle back and forth enforcing const-ness of every local variable.

The argument about optimization is almost certainly premature optimization. Most of the time how you write a loop doesn't matter. You only find out what matters via profiling and refactor accordingly.

[hhmc]

> If you as a reader need const to make sure a local variable is not changed this is usually a symptom of this function being too long to see at a glance

If the compiler can enfore an invariant (constness), why cede that functionality on the hopes you can ensure it yourself?

By the same line of argumentation you should do away with the static type system.

[gintery]

Most people hate const at first (myself included) but once you get used to it, it really does reduces mental load. Not having to glance around is precisely the point, its not a big thing but it does help.

[xfs]

I stopped using it for locals after it increased my mental load. The maintenance cost of const for all local variables is huge during refactor like you're fighting it just to get things done. And in most cases where the type of a variable matters I do have to glance around like when I need to remove a variable or change its type or refactor its dependent variables so const doesn't really for those cases.