Rust doesn't have
-- operator, which some other languages have.
-- operator in Rust code, the compiler yields warnings as follows:
warning: variable does not need to be mutable --> src/main.rs:2:9 | 2 | let mut dec = 10; | ----^^^ | | | help: remove this `mut` | = note: `#[warn(unused_mut)]` on by default warning: unused unary operation that must be used --> src/main.rs:4:9 | 4 | --dec; | ^^^^^ | = note: `#[warn(unused_must_use)]` on by default warning: 2 warnings emitted
These warnings are useful to notice the operator doesn't exist, but I think it's still not a proper warning for beginners. How about a suggestion like this:
warning: -- operator doesn't exist --> src/main.rs:4:9 | 4 | --dec; | ^^^^^ | help: do you mean "dec -= 1;" = note: `#[warn(unused_must_use)]` on by default