Question titles collapse "-​- " (double minus signs) to "— " (mdash) [duplicate]

Question

-- in a title is collapsed to —. This probably isn't so great if the title contains <!-- --> or x--.

Is this intended behavior?

---

Running this query on data.stackexchange (I don't claim to be good at SQL):

SELECT
    sum(case when Title LIKE '% -- %' then 1 else 0 end) AS [mdash],
    sum(case when Title LIKE '% <!-- %' then 1 else 0 end) AS [comment],
    sum(case when Title LIKE '%[a-z0-9]-- %' then 1 else 0 end) AS [decrement],
    sum(case when Title LIKE '% --[a-z0-9]%' then 1 else 0 end) AS [increment],
    sum(case when (Title LIKE '%-- %' OR Title LIKE '%--- %')
              and Title NOT LIKE '% -- %'
              and Title NOT LIKE '% <!-- %'
              and Title NOT LIKE '%[a-z0-9]-- %'
              and Title NOT LIKE '% --[a-z0-9]%' then 1 else 0 end) AS [uncategorized] FROM Posts

I get the following results:

mdash comment decrement increment uncategorized
7665  34      368       1752      472

The vast majority of valid uses cases would be unaffected by Tim Stone's proposal

Answer 1

Yes, although obviously it's not perfect in that it can't detect your intent when you actually mean to have double hyphens. Titles are modified based loosely on rules from SmartyPants, which include transforming -- and --- to — (—).

The regular expression used to do the replacement is just ---?(\s), which may be considered incorrect on the grounds that most style guides frown on putting spaces around en/em dashes…but given that the trailing space is in fact a requirement here, requiring a leading one might be a reasonable way to reduce incorrect conversions (validity of including code snippets in titles aside).