> Why do you need rustup if Rust is so backward compatible
To cross compile. To have quick toolchain updates. To get bleeding edge compiler improvements (e.g. speed) quickly. To test out new features. To help find bugs in the compiler.
One very common use case of rustup is to use clippy. Clippy is a developer tool which hooks directly into the compiler and uses all sorts of private APIs, an inherently unstable thing. It only works on nightly. Lots of people write their code to work on stable, but want to use this tool so they use rustup. Note that no language has a stable way of hooking into the compiler.
Very few rust packages only work with nightly. Care to provide some examples?
To cross compile. To have quick toolchain updates. To get bleeding edge compiler improvements (e.g. speed) quickly. To test out new features. To help find bugs in the compiler.
One very common use case of rustup is to use clippy. Clippy is a developer tool which hooks directly into the compiler and uses all sorts of private APIs, an inherently unstable thing. It only works on nightly. Lots of people write their code to work on stable, but want to use this tool so they use rustup. Note that no language has a stable way of hooking into the compiler.
Very few rust packages only work with nightly. Care to provide some examples?