--> /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library/core/src/ cmp.rs:964:8 For more information about this error, try `rustc --explain E0308`. 31/562Rust 程序设计语言 简体中文版 error: could not compile help: consider making this binding mutable | 2 | let mut x = 5; | +++ For more information about this error, try `rustc --explain E0384`. error: could not compile `variables` (bin "variables") spaces = spaces.len(); | ^^^^^^^^^^^^ expected `&str`, found `usize` For more information about this error, try `rustc --explain E0308`. error: could not compile `variables` (bin "variables")