Let me know when you manage to optimize "if (collatz(n) == 1) { ... }" to just "{ ... }" since you seem to think issues of logic like independence and terminati

Let me know when you manage to optimize "if (collatz(n) == 1) { ... }" to just "{ ... }" since you seem to think issues of logic like independence and termination and how all of that is tied into the type system have no bearing on optimization. The fact that you don't know if "collatz(n)" is always 1 or not means you are limited by the compiler's termination limit for inling and simplifying certain expressions. So the fact that the compiler terminates indeed has a lot of bearing on what kinds of optimizations are allowed and derivable in the absence of an expressive enough type system. Some people might object to that example but the fact remains that logic and type systems are intimately tied to program analysis and optimization. In the domain of pointer alias analysis there is something known as separation logic which allows for statically analyzing aliasing relations. Now if this information is encoded as part of the type system then certain mechanical derivations about aliasing become much simpler which leads to more optimization opportunities. Rust's type system I believe is more related to affine logic but similar arguments still apply. You can not express the invariants that can be expressed with Rust's type system in C++. Actually I take that back. You could in theory encode affine or separation logic with the template system and then encode your program using those templates but that's basically the same work as re-implementing Rust in C++. This means Rust's type system allows for program optimizations that would not be possible otherwise. Similar to how knowing "collatz(n)" always being 1 allows you to elide that condition entirely. No amount of inlining and simplifying will allow you to perform that same optimization.