Currently when parsing the info-string to determine the codeblock language the word up to the first space character is used:

This causes issues with markdown such as in the regex readme using the info-string rust,ignore, it is passed into the syntax highlighter as the string rust,ignore and applied as an attribute class="language-rust,ignore" on the element. Both rustdoc and github support the , character being a delimiter between the language and additional attributes (rustdoc actually supports more, but that's for back-compat, afaik only [ ,] is intended to be used).