pulldown-cmark: Problems with escaping pipes in tables

There doesn’t seem to be a way to escape pipes inside a backtick string inside a table. Example:

| My Table |
|----------|
| `Foo \| Bar` |

Returns a code event with the literal backslash still in it: Code(Borrowed("Foo \\| Bar")).

However, if you don’t include the backslash, it breaks the table (and indeed, that is what GitHub renders here):

This is complicated since inside a backtick string per the commonmark spec, “All backslashes are treated literally”. The GHFM spec has an escape hatch here where they specify “Include a pipe in a cell’s content by escaping it, including inside other inline spans”. So there is a little conflict there, but I think if pulldown-cmark wants to follow GHFM tables, it should probably handle escapes the same way.

A workaround for now is to use HTML, such as <code>Foo \| Bar </code> or <code>Foo &vert; Bar </code>

EDIT: Original issue below, the rest of the issues below have been fixed.

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I’m running into some issues with escaping pipes which makes it difficult to use them in tables.

Escaping only works at the beginning inside backticks

Given the text `\|` I get the expected event Code(Borrowed("|")).

Given the text `foo \|` I get Code(Borrowed("foo \\|")), notice the unexpected backslash in the output. Escaping a pipe only works if it is the very first thing inside backticks. I would expect it to work anywhere inside backticks.

Escaping inside code block does not work

Given the text <code>\|</code> results in exactly the same output (that is, with the backslash). I would expect the backslash to be removed (and is how GitHub interprets it). This is an issue because if you try to use <code>|</code> inside a table, the pipe is interpreted as a column separator. Adding the backslash prevents that, but results in an unwanted backslash in the output.

For now I think I’ll be able to work around this using |.