I've checked all over the net for a solution, I followed all the steps described in the documentation but can't get StyleCopTreatErrorsAsWarnings to work, that is, throw errors instead of warnings.
I have a team project where I added the Stylecop files in the solution so it works even if you don't have it installed:
Then in the solution projects, I import the targets file:
Most of the time, the setting is just ignored - note that I also tried setting it in individual projects (as described in the docs) instead of the .targets file - just figured it's more efficient to do it at root level.
Most of the time means, if I switch the order of the <Import> tags for example it'll throw errors on rebuild but just once, the 2nd time it returns to ignoring it, sort of like a broken caching mechanism.
Note the paths are NOT ignored (stylecop.dll or the path to .targets file), I changed the paths to bogus ones just to check and it gives me a compiler error that it cannot find the referenced file.
Same thing happens on the build server and every other dev's machine, so it's definitely a configuration issue, just can't tell where.
I'm running VS 2012 Ultimate Update 2 + Resharper 7.1.3 in case it helps.