Untrue (presumably outdated) information about `if let`

[creeper6530]

• I have searched open and closed issues and pull requests for duplicates, using these search terms:
  • "if let"
  • ch 19-2
  • age > 30
  • &&
• I have checked the latest main branch to see if this has already been fixed, in this file:
  • https://github.com/rust-lang/book/blob/main/src/ch19-01-all-the-places-for-patterns.md

URL to the section(s) of the book with this problem:

https://doc.rust-lang.org/stable/book/ch19-01-all-the-places-for-patterns.html#conditional-if-let-expressions

Description of the problem:

In chapter 19.1, near the end of section "Conditional if let Expressions", the following is written:

We can’t combine these two conditions into if let Ok(age) = age && age > 30. The new age we want to compare to 30 isn’t valid until the new scope starts with the curly bracket.

This is not true at the latest stable version of Rust. The following code, tested in the playground with Rust 1.92.0, edition 2024, works as expected, comparing to the "unwrapped" age of type u8:

fn main() {
    let age: Result<u8, _> = "34".parse();

    if let Ok(age) = age && age > 30 {
        println!("Above 30: {}", age);
    } else if let Ok(age) = age {
        println!("Not above 30: {}", age);
    } else {
        println!("Err");
    }
}

Suggested fix:

Update the note to reflect the actual state of affairs. Hopefully a simple, quick fix.

[creeper6530]

Attempting it in the playground, setting edition to 2015, gives me the following error:

error: let chains are only allowed in Rust 2024 or later
 --> src/main.rs:4:8
  |
4 |     if let Ok(age) = age && age > 30 {
  |        ^^^^^^^^^^^^^^^^^

Checking the Rust edition guide, it appears that this has indeed been made possible only in Rust 2024 edition. Not 100% sure if this is relevant, but mentioning it just in case.