immerrr/lua-mode — pull request #43 by ryuslash (2012-09-15 23:42:06+00:00)
Title: Fix highlighting of single-line comments

I seem to have been experiencing the same issues as #42, this fixes it in emacs trunk, I haven't checked it on any other version of emacs, but as long as the parameters for `modify-syntax-entry` haven't changed I can't imagine it breaking anything.