Rustfmt doesn't work in for_each blocks with long strings literals

[tafia]

Rustfmt fails to format for_each blocks when there is a long str literal.

• example before running rustfmt:

fn main() {
    // this block will be properly formatted
    {
        let a = 1;
    let b=2;
    let c = " very very very very very very very very very very very very very very very very very very long string in a block";
    }

    let v = vec![1, 2];

    // this block won't be formatted
    v.iter().for_each(|_| {
        let a = 1;
    let b=2;
    let c = " very very very very very very very very very very very very very very very very very very long string in a block";
    });

    // this block with shorter str will be properly formatted
    v.iter().for_each(|_| {
        let a = 1;
    let b=2;
    let c = " less very very long string in a block";
    });
}

• after running rustfmt

fn main() {
    // this block will be properly formatted
    {
        let a = 1;
        let b = 2;
        let c = " very very very very very very very very very very very very very very very very very very long string in a block";
    }

    let v = vec![1, 2];

    // this block won't be formatted
    v.iter().for_each(|_| {
        let a = 1;
    let b=2;
    let c = " very very very very very very very very very very very very very very very very very very long string in a block";
    });

    // this block with shorter str will be properly formatted
    v.iter().for_each(|_| {
        let a = 1;
        let b = 2;
        let c = " less very very long string in a block";
    });
}

Not sure if this is a known bug or not ...

EDIT: added example with short &str in for_each block.

[scampi]

There are some other similar issues, e.g., #3206 and #3135 . From what I remember with these other issues, there is a call to wrap_str that is cancelling any attempts to format that closure.
If you can use the format_strings option, then that block can be formatted.

[calebcartwright]

closing as duplicate of #3863 (realize this is older, but the other issue has more active discussion and plans for next steps so would prefer to consolidate things there)