Strange comment formatting

$ rustfmt --version
rustfmt 1.4.9-nightly (33e3667 2019-10-07)

---

Code:

struct Foo {
    // a: i32,
    //
    // b: i32,
}

Formatting with rustfmt foo.rs:

struct Foo {
    // a: i32,
//
// b: i32,
}

I expected rustfmt to leave the code unmodified.

---

Code:

struct Foo {
    a: i32,
    //
    // b: i32,
}

Formatting with rustfmt format_code_in_doc_comments=true src/foo.rs:

struct Foo {
    a: i32,
    /*
     * b: i32, */
}

I expected rustfmt to leave the code unmodified.

[pickfire]

Maybe off-topic, I just wonder if I should create a new issue (or I am lazy).

/// Hello
/// world.

Should be formatted as

/// Hello world.

But if the sentence already ends.

/// Hello.
/// World.

Then it should be the same. Other languages may need to be checked as well.

[ytmimi]

Going to close this as #5171 fixes the indentation for empty struct comments and #5091 fixes the format_code_in_doc_comments=true issue.