aspect CheckModuleInterfaceContents {
	public void ASTNode.checkModuleInterfaceContents() {}
	public void ModuleCompilationUnit.checkModuleInterfaceContents() {
		if (!isModuleInterface()) {
			return;
		}
		//for now, interfaces should have no member decls (except package exports), and no member CUs
		for (ModuleMemberDecl member : getModuleMemberDeclList()) {
			if (!(member instanceof ModuleExportDecl)) {
				getModuleDecl().error("Module interfaces must not have any imports, merges or replaces.");
			}
			if (member instanceof ModuleExportAllDecl) {
				getModuleDecl().error("Module interfaces must not have an export all packages declaration.");
			}
		} 
		if (getCompilationUnitList().getNumChild() > 0) {
			String fileList = "";
			boolean first = true;
			for (CompilationUnit cu : getCompilationUnitList()) {
				if (!first) {
					fileList += ", ";
				}
				fileList += cu.relativeName();
				first = false;
			}
			getModuleDecl().error("Module interfaces should have no member compilation units. Offending files: " + fileList);
		}
	}
}