[英]Why does Rust compile my project again with `cargo build --release` followed by `cargo run`?
[英]Why does this Rust 2018 code compile with `cargo build` but not using rustc?
在使用cargo build编译以下代码段时,借用检查器似乎很好,但是在使用rustc时出现错误
error[E0502]: cannot borrow `char_counts` as mutable because it is also borrowed as immutable
--> src/lib.rs:14:17
|
10 | let count = char_counts.get(&char);
| ----------- immutable borrow occurs here
...
14 | char_counts.insert(char, rem);
| ^^^^^^^^^^^ mutable borrow occurs here
...
19 | }
| - immutable borrow ends here
任何想法为什么会发生这种情况?
use std::collections::HashMap;
pub fn anagram(word: &str, another_word: &str) -> i32 {
let mut char_counts = HashMap::new();
for char in word.chars() {
let count = char_counts.entry(char).or_insert(0);
*count += 1;
}
for char in another_word.chars() {
let count = char_counts.get(&char);
if let Some(val) = count {
let rem = val - 1;
if rem > 0 {
char_counts.insert(char, rem);
} else {
char_counts.remove(&char);
}
}
}
println!("{:?}", char_counts);
return char_counts.keys().len() as i32;
}
cargo --version
和rustc --version
命令都输出1.33
如果启用了非词性生存期 ,则此函数可以正常编译,并且如果没有它们,就无法编译。 默认情况下,2018版启用它们。 也许您在Cargo.toml
具有edition = "2018"
,但是在直接使用rustc时没有将其作为参数传递吗?
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