Why doesn't allow unreachable code work here

help
1

It's definitely not a big deal. But I want to understand this. I thought placing #[allow(unreachable_code)] would stop the warning

26 |     println!("after exit");
   |     ^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
   |
   = note: `#[warn(unreachable_code)]` on by default

The lines in the code are

    std::process::exit(0);

    #[allow(unreachable_code)]
    println!("after exit");

My understanding was that if I placed allow unreachable_code above some lines of code the unreachable code warning for those lines would be suppressed. Can anyone please help me understand this? thanks,

2

It's likely due to the fact that println! expands to multiple statements, and allow is applied only to the first of them. By wrapping the macro in block, so that it will be one statement, I've got rid of warning - playground:

fn main() {
    return;
    #[allow(unreachable_code)]
    {
        println!("text");
    }
}
2 Likes
3

Thanks. Adding the braces worked.

4

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