{"action":"created","issue":{"url":"https://api.github.com/repos/latex3/svn-mirror/issues/223","labels_url":"https://api.github.com/repos/latex3/svn-mirror/issues/223/labels{/name}","comments_url":"https://api.github.com/repos/latex3/svn-mirror/issues/223/comments","events_url":"https://api.github.com/repos/latex3/svn-mirror/issues/223/events","html_url":"https://github.com/latex3/svn-mirror/issues/223","id":95513683,"number":223,"title":"Trailing optional args from xparse fail in array preamble","user":{"login":"josephwright","id":654518,"avatar_url":"https://avatars.githubusercontent.com/u/654518?v=3","gravatar_id":"","url":"https://api.github.com/users/josephwright","html_url":"https://github.com/josephwright","followers_url":"https://api.github.com/users/josephwright/followers","following_url":"https://api.github.com/users/josephwright/following{/other_user}","gists_url":"https://api.github.com/users/josephwright/gists{/gist_id}","starred_url":"https://api.github.com/users/josephwright/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/josephwright/subscriptions","organizations_url":"https://api.github.com/users/josephwright/orgs","repos_url":"https://api.github.com/users/josephwright/repos","events_url":"https://api.github.com/users/josephwright/events{/privacy}","received_events_url":"https://api.github.com/users/josephwright/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/latex3/svn-mirror/labels/bug","name":"bug","color":"eb6420"},{"url":"https://api.github.com/repos/latex3/svn-mirror/labels/expl3","name":"expl3","color":"5319e7"}],"state":"open","locked":false,"assignee":{"login":"josephwright","id":654518,"avatar_url":"https://avatars.githubusercontent.com/u/654518?v=3","gravatar_id":"","url":"https://api.github.com/users/josephwright","html_url":"https://github.com/josephwright","followers_url":"https://api.github.com/users/josephwright/followers","following_url":"https://api.github.com/users/josephwright/following{/other_user}","gists_url":"https://api.github.com/users/josephwright/gists{/gist_id}","starred_url":"https://api.github.com/users/josephwright/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/josephwright/subscriptions","organizations_url":"https://api.github.com/users/josephwright/orgs","repos_url":"https://api.github.com/users/josephwright/repos","events_url":"https://api.github.com/users/josephwright/events{/privacy}","received_events_url":"https://api.github.com/users/josephwright/received_events","type":"User","site_admin":false},"milestone":null,"comments":2,"created_at":"2015-07-16T19:54:16Z","updated_at":"2015-07-16T21:14:38Z","closed_at":null,"body":"For example\r\n```latex\r\n\\listfiles\r\n\\documentclass{article}\r\n\\usepackage{xparse}\r\n\\DeclareDocumentCommand\\foo{mO{xxx}}{[#1][#2]}\r\n\\usepackage{array}\r\n\\begin{document}\r\na $x$\r\n\r\n\\tracingmacros2\r\n\r\n%\\begin{tabular}{>{\\foo{zz}[]}l}% works\r\n\\begin{tabular}{>{\\foo{zz}}l}% fails\r\n  text\r\n\\end{tabular}\r\n\\end{document}\r\n```\r\nI have a feeling this is linked to something I've seen in `siunitx` and therefore comes from `expl3` rather than `xparse`. "},"comment":{"url":"https://api.github.com/repos/latex3/svn-mirror/issues/comments/122099448","html_url":"https://github.com/latex3/svn-mirror/issues/223#issuecomment-122099448","issue_url":"https://api.github.com/repos/latex3/svn-mirror/issues/223","id":122099448,"user":{"login":"blefloch","id":722786,"avatar_url":"https://avatars.githubusercontent.com/u/722786?v=3","gravatar_id":"","url":"https://api.github.com/users/blefloch","html_url":"https://github.com/blefloch","followers_url":"https://api.github.com/users/blefloch/followers","following_url":"https://api.github.com/users/blefloch/following{/other_user}","gists_url":"https://api.github.com/users/blefloch/gists{/gist_id}","starred_url":"https://api.github.com/users/blefloch/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/blefloch/subscriptions","organizations_url":"https://api.github.com/users/blefloch/orgs","repos_url":"https://api.github.com/users/blefloch/repos","events_url":"https://api.github.com/users/blefloch/events{/privacy}","received_events_url":"https://api.github.com/users/blefloch/received_events","type":"User","site_admin":false},"created_at":"2015-07-16T21:14:38Z","updated_at":"2015-07-16T21:14:38Z","body":"It might actually be impossible to get this to work without changing LaTeX2e tabulars, at a minimum to include a command next to the `\\ignorespaces` that appears in the preamble.  I'll think."}}