markdown link parsing bug for urls with underscore [duplicate]

Question

This question already has an answer here:

• Fail of markdown parser detected if '_ 's are used in a naked URL 2 answers

compare auto-link:

http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/quadtrees-r1303

with [url](url) workaround:

http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/quadtrees-r1303

the sole underscore between slashes is enough to trigger this:

http://example.com/_/bug/

and also when you have trailing and leading low-dashes at the same time:

http://example.com/bug/a

or when you mix them with dashes:

http://example.com/_-bug

counter-examples:

http://example.com/_not_a_bug/a

http://example.com/no_bug/a

sorry for abuse of h3 tags, but it was the only wayt to make the post readable.

Answer 1

I'm not familiar enough with the Markdown spec to assess whether this is a bug in the way that SE parses it, or a more general issue that you have with the spec's determination of hyperlinks.

But do note that there are some very simple workarounds, which seem to be sufficient here as you can tell immediately from the preview that the link is broken:

1. Escape the underscore

http://www.gamedev.net/page/resources/\_/technical/graphics-programming-and-theory/quadtrees-r1303

produces…

http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/quadtrees-r1303

2. Don't rely on automatic link interpretation; use the Markdown syntax for links

[Quad Trees](http://www.gamedev.net/page/resources/\_/technical/graphics-programming-and-theory/quadtrees-r1303)

produces…

Quadtrees on GameDev

Note that this also allows you to give your link a descriptive title, which tells people what they're about to click on. It also condenses a long hyperlink down to something more manageable and readable, which makes the post look less ugly. And, my favorite, it encourages you to include links inline with text, rather than on separate lines by themselves.