There's an issue in displaying Mermaid diagrams in Markdown where the double tilde character ~~ is being interpreted as a <del> symbol in markdown.

This character, when entered three times ~~~, represents a special layout in Mermaid diagrams where the elements should be forced to be laid out one on top of the other (in a top-to-bottom diagram). It is a necessary part of Mermaid syntax.

In a mermaid diagram, the tilde character should not be interpreted as a delete symbol.

However, OneDev is trying to interpret it as a strikethrough. I'm not sure if this is an issue with the Markdown engine or the Mermaid engine.

Or a bug in the combination of the way that both work together.

Suspected reason for the bug

It's almost as if OneDev is escaping the syntax before sending it to the Mermaid engine, in a way that should not be done.

Or perhaps it's doing some interpretation first and transforming the syntax before sending it to the Mermaid engine.

Mermaid diagram source

flowchart TD
    LC["Current — removed or replaced"]:::current
    LP["Proposed — added by this fix"]:::proposed
    LM["Common — unchanged"]:::common
    LC ~~~ LP ~~~ LM

What is expected to be displayed?

The error message: what is being displayed?

Parse error on line 5:
...d"]:::common    LC <del>~ LP </del>~ LM
----------------------^
Expecting 'SEMI', 'NEWLINE', 'SPACE', 'EOF', 'AMP', 'COLON', 'START_LINK', 'LINK', 'LINK_ID', 'DOWN', 'DEFAULT', 'NUM', 'COMMA', 'NODE_STRING', 'BRKT', 'MINUS', 'MULT', 'UNICODE_TEXT', got 'TAGSTART'