src/main/java/wycc/WyMain.java
private static String determineSystemRoot() throws IOException {
		String whileyhome = System.getenv("WHILEYHOME");
		if (whileyhome == null) {
			System.err.println("error: WHILEYHOME environment variable not set");
			System.exit(-1);
		}
		return whileyhome;
	}
private static String determineSystemRoot() throws IOException {
		String whileyhome = System.getenv("WHILEYHOME");
		if (whileyhome == null) {
			System.err.println("error: WHILEYHOME environment variable not set");
			System.exit(-1);
		}
		return whileyhome;
	}
Determine the system root. That is, the installation directory for the
compiler itself.

@param tool
@return
@throws IOException