Do not allow reference link labels contain left brackets

[chenzhiguang]

Fix: #335

[srawlins]

Does this fix a Commonmark spec then? Can you run tool/stats.dart --update-files and tool/stats.dart --update-files --flavor=gfm to update the compliance stat files?

[chenzhiguang]

Does this fix a Commonmark spec then? Can you run tool/stats.dart --update-files and tool/stats.dart --update-files --flavor=gfm to update the compliance stat files?

I have updated the stat files by running stats.dart

[srawlins]

We should not change the unit files case-by-case, they are meant to be an exact set of test cases from a single version of the commonmark specs. I'll look into bumping them.

[srawlins]

Sorry, I totally mis-remembered how we maintain the spec tests. @kevmoo can maybe confirm:

tool/stats.dart --update-files will use tool/common_mark_tests.json to run specs, and update all of the unit files in test/.

Then the unit files represent what the markdown package currently outputs, so that a clean checkout will always have 100% tests passing.

tool/common_mark_tests.json is updated separately (download?), e.g. in #383.

When someone improves compliance (like this PR), the unit file changes, and tool/*_stats.json and tool/*_stats.txt are updated (via tool/stats.dart --update-files).

[kevmoo]

I'd have to re-learn, too – even though I wrote it! That sounds right, @srawlins

[kevmoo]

Looks like the output files change, but the stats don't change – so equally broken it seems?

[kevmoo]

So this change seems to make things less broken – but it's still broken.

<p>[foo][ref[]</p>
<p>[ref[]: /uri</p>

According to spec, this is what we should see.

[srawlins]

I'll take the PR because it is strictly better than what we have today 😁. To pass commonmark 545, we just need to also change parsing of the link reference (in addition to the reference link, which you solved).

Thanks!