Avoid misleading closure return type note

[chenyukang]

Fixes #155670

[rustbot]

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[wesleywiser]

Thanks @chenyukang!

@bors r+ rollup

[rust-bors]

📌 Commit 5e00484 has been approved by wesleywiser

It is now in the queue for this repository.

[A4-Tacks]

I'm curious if this has fix this:

struct SmolStr;
const _: fn() -> SmolStr = || {
    match Some(()) {
        Some(()) => (),
        None => return SmolStr,
    };
    let _: String = {
        SmolStr
    };
    SmolStr
};

Or

struct SmolStr;
const _: fn() -> String = || {
    match Some(()) {
        Some(()) => (),
        None => return String::new(),
    };
    let _: String = {
        SmolStr
    };
    String::new()
};

View changes since the review

[chenyukang]

good catch, the first is handled well, but the second case will report an unexpected note, let me rethink it.