rustfmt forcefully moves trailing comments to irrelevant code above (and not idempotent either)

I sometimes write enums with a comment at the end saying something like "I should add foo in the future". Like

enum MyEnum {
    Bar,

    // I should add Foo
}

Unfortunately, rustfmt thinks it would be wise to reformat this into

enum MyEnum {
    Bar,
    // I should add Foo
}

Even worse, when enabling trailing_comma = "Never", I get the non-idempotent output where first it looks like above without the trailing comma, and then gets moved even further up:

enum MyEnum {
    Bar // I should add Foo
}

That formatting is very far from my original intention when writing code, and actively hinders readability as one might now ask why the comment should be related to that last enum variant. I think the behaviour should be changed so that rustfmt leaves the trailing comment with an empty newline as it is.

Reproduce the enum examples with rustfmt, including trailing_comma = "Never", and compare repeated formatting runs. Trace the formatter behavior responsible for moving the trailing comment; done means the comment remains on its empty line and formatting is idempotent.