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[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編譯以下代碼段時,借用檢查器似乎很好,但是在使用rustc時出現錯誤
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
任何想法為什么會發生這種情況?
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
命令都輸出1.33
如果啟用了非詞性生存期 ,則此函數可以正常編譯,並且如果沒有它們,就無法編譯。 默認情況下,2018版啟用它們。 也許您在Cargo.toml
具有edition = "2018"
,但是在直接使用rustc時沒有將其作為參數傳遞嗎?
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