aspect CheckNoSyntheticInstances {
	public void ASTNode.checkNoSyntheticInstances() {}
	public void ModuleCompilationUnit.checkNoSyntheticInstances() {
		if (isSynthetic() && isInstance()) {
			String contextString = "";
			boolean first = true;
			for (ModuleCompilationUnit mcu : getInstanceContext()) {
				if (!first) { 
					contextString += ", ";
				}
				contextString += mcu.getBaseCU().getModuleName();
				first = false;	
			}
			String msg = "Synthetic module " + getBaseCU().getModuleName() + " used in modules " + contextString + " was not replaced with a non-interface module.";
			getModuleDecl().error(msg);
		}
	}
}