Add new `unescaped_pipe_in_table_cell` rustdoc lint by GuillaumeGomez · Pull Request #159583 · rust-lang/rust

GuillaumeGomez · 2026-07-19T22:49:30Z

Fixes #159186.

r? @Urgau

… lint

GuillaumeGomez · 2026-07-21T14:19:25Z

Applied comments.

Urgau

Implementation looks good to me.

View changes since this review

Urgau · 2026-07-21T20:35:29Z

2nd try. Let's do an FCP.

unescaped_pipe_in_table_cell details

`unescaped_pipe_in_table_cell`

This lint is warn-by-default. It detects unescaped pipes (|) in table rows which
lead to some row cells being ignored. For example:

//! | col1 |
//! | ---- |
//! | `code_with(|arg| arg)` |

Which will give:

error: table row has too many columns
  --> $DIR/unescaped_pipe_in_table_cell.rs:5:18
   |
5  | //! | `code_with(|arg| arg)` |
   |                  ^ help: any content after this column divider is discarded
   |
   = help: to escape `|` characters in tables, add a `\` before them like `\|`
note: the lint level is defined here
  --> $DIR/unescaped_pipe_in_table_cell.rs:1:9
   |
1  | #![deny(rustdoc::unescaped_pipe_in_table_cell)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

@rfcbot merge rustdoc-internals

rust-rfcbot · 2026-07-21T20:35:31Z

@Urgau has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

camelid · 2026-07-21T20:40:16Z

+```rust
+//! | col1 |
+//! | ---- |
+//! | `code_with(|arg| arg)` |


Wow TIL that this is how GFM works. Very strange design...

View changes since the review

Yeah I was super confused as well.

notriddle · 2026-07-21T22:30:27Z

+
+#[derive(Diagnostic)]
+#[diag("table row has too many columns")]
+#[help("to escape `|` characters in tables, add a `\\` before them like `\\|`")]


Suggested change

#[help("to escape `|` characters in tables, add a `\\` before them like `\\|`")]

#[help(r"to escape `|` characters in tables, add a `\` before them like `\|`")]

View changes since the review

notriddle · 2026-07-21T22:36:55Z

Please add a test case for tables with fewer cells in a row than the head. I suppose it should be silent, but we want to make sure it doesn’t ICE or something.

| one | two | |-|-| | a | | b

Please add test cases for tables that don’t have leading and trailing pipes. You’re parsing the table syntax, so you need to test these corner cases.

one | two -|- a | b | c a | *[View changes since the review](https://triagebot.infra.rust-lang.org/gh-changes-since/rust-lang/rust/159583/cde3f8aee5a30928872e2438e3f18238a3fa306c..6fd9b1bce2dd4cd99e32dc333104810bef776cc0)*

notriddle · 2026-07-21T22:41:44Z

+    //! | col |
+    //! | ---- |
+    //! | code_with | aaaaa
+    //^ the "aaaaa" part will be ignored.


Why is it ignored? It seems like an example of the thing you’re trying to warn about.

col

code_with

View changes since the review

notriddle · 2026-07-21T22:47:52Z

Minor nits about the implementation, but massive approval for the lint in concept!

rustbot assigned Urgau Jul 19, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Jul 19, 2026

GuillaumeGomez mentioned this pull request Jul 19, 2026

Markdown tables can silently discard content containing | #159186

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Urgau reviewed Jul 20, 2026

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Urgau added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 20, 2026

GuillaumeGomez added 3 commits July 21, 2026 14:06

Add new unescaped_pipe_in_table_cell rustdoc lint

54947cf

Add ui regression test for new rustdoc unescaped_pipe_in_table_cell…

ec0f4db

… lint

Add documentation for rustdoc unescaped_pipe_in_table_cell lint

6fd9b1b

GuillaumeGomez force-pushed the unescaped_pipe_in_table_cell branch from 045f5a3 to 6fd9b1b Compare July 21, 2026 12:16

Urgau approved these changes Jul 21, 2026

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Urgau added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 21, 2026

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rust-rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Jul 21, 2026

Urgau added S-waiting-on-fcp Status: PR is in FCP and is awaiting for FCP to complete. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 21, 2026

camelid reviewed Jul 21, 2026

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notriddle reviewed Jul 21, 2026

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	#[help("to escape `\|` characters in tables, add a `\\` before them like `\\\|`")]
	#[help(r"to escape `\|` characters in tables, add a `\` before them like `\\|`")]

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GuillaumeGomez commented Jul 19, 2026

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Urgau commented Jul 21, 2026

unescaped_pipe_in_table_cell

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notriddle commented Jul 21, 2026

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`unescaped_pipe_in_table_cell`

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