The easiest way to fix this is to go to "Settings -> Environment -> Environment variables" and add "LC_ALL" as variable and set it to either an english flavour or (more easy) to "C".
Is it possible to just force it in the compiler plugin?
This is what I'd really do, too. But unluckily, this tremendously stupid thing called "internationalization" is something that a lot of people actually want at every price, even if it kills them. I fear we'd be getting an equal amount of complaints if we forced compiler output to English.
The only solution that would probably work without complaints would be to force to English, and compile files that contain errors again (secretly, in a second pass) to display error messages in a local language, if that is desired. Bah.
I'm certainly OK with having menus and dialogs in German (assuming translations are not of the "typical" quality), but in regards of anything that I might have to type (shell commands, formulas, ...) or find on the internet, it's a nightmare. The same goes for anything a parser might have to decipher.
Try and find out what a Windows service (pick one with a particularly gay sounding name) does. The translated decription consists of only makeup-words that you can't understand as a native speaker. If you type the name into Google, you get directed to some machine-translated fuckshit at MSDN that no sane person can decipher.
Now, if the entire thing was just English (including the service's name) it wouldn't be any kind of problem.
I'm still waiting for the day when you open a command prompt and have to type
wv to change a directory and
ld to delete a file... It's already like that in MS Excel (and all of its puny clones like OO) where you have to type
MITTELWERT or
WENN when you mean
AVG or
IF (which every half-savy person should be able to type, even if they don't have English as native language).