Extra blank line inserted before code blocks in doc comments #6695

Activity

1. jieyouxu

   added

   E-fixed-needs-confirmationCall for participation: expected to have been fixed, needs confirmationCall for participation: expected to have been fixed, needs confirmation

   only-with-optionRequires a non-default option value to reproduceRequires a non-default option value to reproduce

   UO-wrap_commentsUnstable option: wrap_commentsUnstable option: wrap_comments

   S-fixed-needs-subtree-syncStatus: fixed, but needs a subtree syncStatus: fixed, but needs a subtree sync

   and removed

   E-fixed-needs-confirmationCall for participation: expected to have been fixed, needs confirmationCall for participation: expected to have been fixed, needs confirmation

   on Oct 23, 2025
2. ytmimi commented on Aug 28, 2026

   

   ytmimi

   on Aug 28, 2026

   Contributor

   More actions

   @siddhardh-codemonk Maybe you can take a look at this one. To test is out I'd create an input file (issue_6695.rs):

   /// Some doc comment with code snippet:
   ///```
   /// '\u{1F}
   /// ```
   pub struct Code {}

   You can run cargo run --bin rustfmt -- --emit=stdout --config=max_width=20,wrap_comments=true path/to/issue_6695.rs from the root of the rustfmt repo to build run and from source. I'm setting --emit=stdout so that we don't override the original input file and --config=max_width=20,wrap_comments=true just passes all the configuration options needed to reproduce.

   With all that, rustfmt produces this:

   Output:

   /// Some doc comment
   /// with code snippet:
   /// 
   /// ```
   /// '\u{1F}
   /// ```
   pub struct Code {}

   error[internal]: line formatted, but exceeded maximum width (maximum: 20 (see `max_width` option), found: 22)
    --> path/to/issue_6695.rs:2:2:21
     |
   2 | /// with code snippet:
     |                     ^^
     |
     = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals
   
   error[internal]: left behind trailing whitespace
    --> path/to/issue_6695.rs:3:3:4
     |
   3 | /// 
     |    ^
     |
     = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals
   
   warning: rustfmt has failed to format. See previous 2 errors.
   

   If you're having issues / have questions you can leave comments here or message me on Zulip
3. siddhardh-codemonk commented on Aug 29, 2026

   

   siddhardh-codemonk

   on Aug 29, 2026

   More actions

   Thanks again for the repro! I dug into this and found there are actually two separate bugs causing the two errors:

   Trailing whitespace — traced to how handle_line pushes a space for continuation, then separately pushes a newline when a code block starts, without cleaning up the earlier space. Opened a PR fixing this: #7083
   Width overflow — this one's in break_string's MIN_STRING threshold rejecting a valid break point and falling through to a forward search that doesn't re-check the width limit. It's more involved since it's shared wrapping logic used elsewhere, so I wanted to flag it here first rather than guess at a fix. Happy to take a swing at it if you can confirm the right direction (e.g. should the forward-search fallback verify width before accepting, or should MIN_STRING behave differently in this case?).
4. ytmimi

   removed

   S-fixed-needs-subtree-syncStatus: fixed, but needs a subtree syncStatus: fixed, but needs a subtree sync

   on Oct 6, 2026
5. ytmimi

   added a parent issue on Oct 6, 2026

   • [unstable option] wrap_comments #3347
6. jieyouxu

   added

   C-bugCategory: this is a bug; use also I-* labels for specific bug kinds, e.g. I-non-idempotency or I-ICECategory: this is a bug; use also I-* labels for specific bug kinds, e.g. I-non-idempotency or I-ICE

   on Oct 12, 2026