Markdown tables can silently discard content containing `|`

[kpreid]

Code

//! This is a table with some columns:
//!
//! | col1 | col2 | col3 | col4 |
//! | ---- | ---- | ---- | ---- |
//! | `one` | `two` | three | four |
//! | `code_with(|arg| arg)` |  `code_with(|arg| arg)` | three | four |

Reproduction Steps

cargo doc

Expected Outcome

Table should contain all the text I wrote, or an error or warning should be reported.

Actual Output

The table entries are split on pipes disregarding the code backticks, and the resulting "extra columns" are silently discarded:

This is apparently the specified behavior of GitHub-Flavored-Markdown tables, but it is certainly surprising. There should be at least a warning that content is being discarded.

[zachs18]

I agree that ideally there'd be a warning if a row of a table has more columns than the table itself (such that some are discarded).

Maybe something like

warning: table row has too many columns
 --> src/lib.rs:1:41
  |
6 | //! | `code_with(|arg| arg)` |  `code_with(|arg| arg)` | three | four |
  |                                            ^ any content after this column divider is discarded
  |
  = help: this table only has 4 columns
  = help: to escape `|` characters in tables, add a `\` before them like `\|`.
  = note: `#[warn(rustdoc::oh_no_our_table_its_broken)]` on by default

[GuillaumeGomez]

That sounds like a bug in pulldown-cmark (the crate we use in rustdoc to handle markdown).

[GuillaumeGomez]

So apparently, like mentioned by @zachs18, the | character needs to be escaped because pulldown-cmark follows the GFM spec. I agree that adding a warning here would be nice. Doing that.

EDIT: And it was also written in the first comment. I should re-read the full issue when I come back to it after some time. ^^'

[GuillaumeGomez]

Opened #159583.