wrap_comments breaks markdown formatting

[mrmonday]

Given the following:

//! This is a list:
//!  * Outer
//!  * Outer
//!   * Inner
//!   * Inner with lots of text so that it could be reformatted something something something
fn main() {
}

rustfmt, with wrap_comments set to true, is reformatted as:

//! This is a list:
//!  * Outer
//!  * Outer
//!   * Inner
//! * Inner with lots of text so that it could be reformatted something
//! something something
fn main() {
}

Notice that the inner bullet point is no longer part of either list.

[mrmonday]

I also encountered similar problems for code blocks within comments - I haven't reported a separate bug - should I?

[nrc]

There is already an issue for broken code blocks in comments. We have a lot of problems with comments right now :-(

[daboross]

Another test case:

//! This example shows how to configure fern to output really nicely colored logs
//! - when the log level is error, the whole line is red
//! - when the log level is warn, the whole line is yellow
//! - when the log level is info, the level name is green and the rest of the line is white
//! - when the log level is debug, the whole line is white
//! - when the log level is trace, the whole line is gray ("bright black")

is reformatted as

//! This example shows how to configure fern to output really nicely colored
//! logs - when the log level is error, the whole line is red
//! - when the log level is warn, the whole line is yellow
//! - when the log level is info, the level name is green and the rest of the
//! line is white - when the log level is debug, the whole line is white
//! - when the log level is trace, the whole line is gray ("bright black")

completely breaking the list (it no longer even resembles a list).

(diff output)

-//! This example shows how to configure fern to output really nicely colored logs⏎
-//! - when the log level is error, the whole line is red⏎
+//! This example shows how to configure fern to output really nicely colored⏎
+//! logs - when the log level is error, the whole line is red⏎
 //! - when the log level is warn, the whole line is yellow⏎
-//! - when the log level is info, the level name is green and the rest of the line is white⏎
-//! - when the log level is debug, the whole line is white⏎
+//! - when the log level is info, the level name is green and the rest of the⏎
+//! line is white - when the log level is debug, the whole line is white⏎
 //! - when the log level is trace, the whole line is gray ("bright black")⏎

[Ekleog]

With rustfmt 0.99.2-nightly (5c9a2b6 2018-08-07), getting the following diff:

 ///
-/// All the parameters ***except for `from_theater`*** should be inserted as sent by the remote
-/// theater, ie. as passed to [`Theater::send`] on the remote actor:
-///  * `from` is the sending (remote) [`ActorId`], as reported by the remote theater by theater-specific means
-///  * `to` is the receiving (local) [`ActorId`], as requested by the remote theater
-///  * `tag` is a tag that identifies the message type
-///  * `msg` is the (serialized) message
+/// All the parameters ***except for `from_theater`*** should be inserted as
+/// sent by the remote theater, ie. as passed to [`Theater::send`] on the
+/// remote actor:  * `from` is the sending (remote) [`ActorId`], as reported by
+/// the remote theater by theater-specific means  * `to` is the receiving
+/// (local) [`ActorId`], as
+/// requested by the remote theater  * `tag` is a tag that identifies the
+/// message type  * `msg` is the (serialized) message
 ///

[scampi]

Maybe what could be done is to recognise lines with a leading itemization marker (* or -), which indicates that the line indent should be kept. The line can then be wrapped, taking into account the indent of the item.

Below is an example of what that could look like:

-/// All the parameters ***except for `from_theater`*** should be inserted as sent by the remote
-/// theater, ie. as passed to [`Theater::send`] on the remote actor:
-///  * `from` is the sending (remote) [`ActorId`], as reported by the remote theater by theater-specific means
-///  * `to` is the receiving (local) [`ActorId`], as requested by the remote theater
+/// All the parameters ***except for `from_theater`*** should be inserted as
+/// sent by the remote theater, ie. as passed to [`Theater::send`] on the remote
+/// actor:
+///  * `from` is the sending (remote) [`ActorId`], as reported by the remote
+///    theater by theater-specific means
+///  * `to` is the receiving (local) [`ActorId`], as requested by the remote
+///    theater
 ///  * `tag` is a tag that identifies the message type
 ///  * `msg` is the (serialized) message