我认为这可以工作：
const x: &str = "10"; // declare a const
let x: i32 = x.parse().unwrap(); // reuse the same name for a let binding
assert_eq!(10, x);
但：
error[E0308]: mismatched types
--> src/main.rs:3:9
|
3 | let x: i32 = x.parse().unwrap(); // reuse the same name for a let binding
| ^ expected i32, found reference
|
= note: expected type `i32`
found type `&'static str`
error[E0277]: the trait bound `{integer}: std::cmp::PartialEq<&str>` is not satisfied
--> src/main.rs:4:5
|
4 | assert_eq!(10, x);
| ^^^^^^^^^^^^^^^^^^ can't compare `{integer}` with `&str`
|
= help: the trait `std::cmp::PartialEq<&str>` is not implemented for `{integer}`
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
这有效：
const x: &str = "10";
let y: i32 = x.parse().unwrap();
assert_eq!(10, y);
这样：
let x: &str = "10";
let x: i32 = x.parse().unwrap();
assert_eq!(10, x);
我是在做错什么，还是不能const用let相同的名字遮盖现有的绑定？
我想我明白了...当我使用时let SOME_CONST，编译器认为我正在进行模式匹配。
当我修复类型时：
const x: i32 = 10;
let x: i32 = x + 1;
assert_eq!(11, x);
我收到另一个错误：
error[E0005]: refutable pattern in local binding: `_` not covered
--> src/main.rs:3:9
|
3 | let x: i32 = x + 1;
| ^ interpreted as a constant pattern, not new variable
好像我已经x将程序中的所有事件都发生了，并将它们扩展为常数10：
let 10: i32 = 10 + 1;
assert_eq!(11, x);
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我来说两句