Fix FP on if_then_some_else_none when there is early return

[dswij]

closes #7870

changelog: [if_then_some_else_none] now does not fire when there is early return

[rust-highfive]

r? @xFrednet

(rust-highfive has picked a reviewer for you, use r? to override)

[xFrednet]

The implementation looks good to me.

---

For future reference: The example in the issue could in theory still use bool::then() and then call flatten on the result like this(playground)

 fn f2(b: bool, v: Option<()>) -> Option<()> {
    b.then(|| {
        v?;
        Some(())
    })
    .flatten()
}

However, this only works if the early return is also inside the return expression of function. I like this solution implemented in this PR. Just wanted to document it for future reference 🙃

[xFrednet]

Looks good, only one small formatting NIT 😅

[xFrednet]

rustfmt sadly doesn't work inside macros. Could you fix this indention and the one in line 103? Then it's all good 👍

[dswij]

Hm, I thought that this change was because of rustfmt 🤔

[xFrednet]

These indentations also often happen in my editor, when I move code around. It's good that rustfmt is really solid otherwise, and this might be fixed when Rust supports if let chains in the future 🙃

[xFrednet]

Looks good to me, thank you for the bug fix! 🙃

@bors r+

[bors]

📌 Commit ec3d1c8 has been approved by xFrednet

[bors]

⌛ Testing commit ec3d1c8 with merge d6c707d...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: xFrednet
Pushing d6c707d to master...