Rust, unlike other languages I know of, has a well defined process to make breaking changes to the language. These changes are opt-in on a crate level so you don’t need to migrate an entire code base in an instant. The team also ships tools to auto fix code out there to make the migration easier.

The 2018 edition had a few small breaking changes, the 2021 edition will have none. Personally I hope the 2024 edition makes some breaking changes to make IDE development easier.

C++ is backwards compatible the same way and there was never any need to migrate your code. What happened was that c++11 brought in a major set of new features, changing the best practices of how to use the language, almost to the point of making it a new language. Mainly smart pointers, initializers, type inference, threading and lambdas, and removing tons of other small rocks in the shoe.

So that someone familiar with c++11 or newer opening up a legacy code would maybe not have a hard time understanding it but they would go "wtf is this verbose shit" and be tempted to rewrite it. Vice versa an old schooler would need to relearn these new features when opening a new code base.

Not from the Rust project; someone else would have to come along and build it.

I mean there will be more and more changes to Rust, just like how C++ has had many changes over the years. Rust 2020, .. 2025, 2026 etc..