Rollup merge of #131035 - dingxiangfei2009:tweak-if-let-rescope-lint, r=jieyouxu

Preserve brackets around if-lets and skip while-lets

r? `@jieyouxu`

Tracked by #124085

Fresh out of #129466, we have discovered 9 crates that the lint did not successfully migrate because the span of `if let` includes the surrounding brackets `(..)` like the following, which surprised me a bit.

```rust
if (if let .. { .. } else { .. }) {
// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// the span somehow includes the surrounding brackets
}
```

There is one crate that failed the migration because some suggestion spans cross the macro expansion boundaries. Surely there is no way to patch them with `match` rewrite. To handle this case, we will instead require all spans to be tested for admissibility as suggestion spans.

Besides, there are 4 false negative cases discovered with desugared-`while let`. We don't need to lint them, because the `else` branch surely contains exactly one statement because the drop order is not changed whatsoever in this case.

```rust
while let Some(value) = droppy().get() {
..
}
// is desugared into
loop {
    if let Some(value) = droppy().get() {
        ..
    } else {
        break;
        // here can be nothing observable in this block
    }
}
```

I believe this is the one and only false positive that I have found. I think we have finally nailed all the corner cases this time.

0 files changed, 0 insertions, 0 deletions