+++
title = "Tricky questions for any rust interview"
draft = true
date = "2022-08-18"

[taxonomies]
tags = ["rust"]
+++

Which type has variable `result`?
```rust
fn count_uppercase(s: &str) -> usize {
    let result = {
        let upper = s.chars().filter(|c| c.is_uppercase()).collect::<String>();
        return upper.len();
    };
}
```

<details><summary>Answer</summary>

`result` has '!' type or 'never type'. . [Read more](https://doc.rust-lang.org/book/ch19-04-advanced-types.html#the-never-type-that-never-returns)

</details>