$ lessc --include-path=/home/spage/projects/core/resources/mediawiki.less/ resources/mediawiki.ui/vector.less
FileError: 'mediawiki.mixins' wasn't found in .../resources/mediawiki.ui/components/default/buttons.less on line 1, column 1:
1 @import "mediawiki.mixins";
It seems lessc requires you include the extension when importing files from the include path. If I change the line in buttons.less to
then lessc fails with
ParseError: Unrecognised input in .../resources/mediawiki.less/mediawiki.mixins.less on line 15, column 18:
15 background-image: url(@url)!ie;
lessc doesn't like the !ie. We actually use this in e.g. mediawiki.action.view.postEdit. Maybe it needs to be quoted or escaped in some way.
Our PHP compiler in includes/lib/lessc.inc.php is obviously different code than the nodejs implementation, but we should avoid gratuitous incompatibilities.
An alternative to using lessc is to use ResourceLoader to generate the CSS, e.g.
http://en.wikipedia.org/w/load.php?debug=true&lang=en&modules=mediawiki.ui&only=styles&skin=vector&* , and save the resulting file.