Chain comments after `.` prevent chain from being formatted because comment would be lost

If a comment follows the . in a chain, then the chain is not formatted because a comment would be lost. This behavior can be seen when running rustfmt with error_on_unformatted=true. However the chain is rewritten if the comment comes before the .

tested using rustfmt 1.5.1-nightly (ef911542 2022-09-19).

Input

fn not_formatted() {
    let a = b./*cc*/       ddd;
    let e = f.// gg
hhh;
}

fn formated() {
    let i = j/*kk*/       .lll;
    let m = n// oo
.ppp;
}

Output

fn not_formatted() {
    let a = b./*cc*/       ddd;
    let e = f.// gg
hhh;
}

fn formated() {
    let i = j /*kk*/
        .lll;
    let m = n // oo
        .ppp;
}

Error Output

error[internal]: not formatted because a comment would be lost
 --> <stdin>:2
  |
2 |     let a = b./*cc*/       ddd;
  |
  = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals

error[internal]: not formatted because a comment would be lost
 --> <stdin>:3
  |
3 |     let e = f.// gg
  |
  = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals

I think the issue is that we don't expect to find comments after the . when rewriting ChainItem, and the examples above specifically highlight the ChainItemKind::StructField match arm:
https://github.com/rust-lang/rustfmt/blob/ef91154250977b3b5d05448dafbca524a1168b47/src/chains.rs#L246-L271

Start in src/chains.rs at the ChainItemKind::StructField match arm referenced by the issue, and reproduce the examples with rustfmt and error_on_unformatted=true. Trace how comments after the dot are handled, then verify that both block and line comments remain preserved and the chain is formatted without the lost-comment error.