There is already a JIRA issue filed for this (IDEA-18037), however it is listed as a low-priority bug. After I had upgraded to Diana, I am finding that a small number of my string constants (primarily, some strings that define regular expression patterns) in various classes and projects are showing up highlighted as errors. Not all regex patterns are misinterpreted, of course, and many of complex patterns are treated correctly. However, some show up highlighted. I ahve attached a screenshot to the issue in JIRA. Although the projects still build ok, it looks dirty to have files in my projects that are error-highlighted for no reason. Needless to say, it becomes confusing to tell which class indeed contains a legitimate compilation error.
I see that issue IDEA-18037 was originally filed in May, and it has not been addressed yet. Perhaps, it is due to the fact that the priority was set to "low" by the reporter, and, possibly, due to the misleading description that implied that the issue might have to do with SQL strings in prepared statements, specifically. The latter, clearly, is not the case, since it seems to be a general string parsing problem in Diana. I think the issue must be upgraded to a higher priority and attended ASAP.