aspect CheckModuleInterfacePackageImplements {
	//checks if the exported packages in implemented interfaces are actually found
	//in the MCUs local package map
	//should be done after collect local module packages
	public void ASTNode.checkModuleInterfacePackageImplements() {}
	public void ModuleCompilationUnit.checkModuleInterfacePackageImplements() {
		if (isModuleInterface()) {
			return;
		} 
		if (!isModuleInstantiated()) {
			return;
		}
		//check if the exported packages in the implemented interfaces are part of
		//the exported local packages here
		for (ModuleAccess ma: getModuleDecl().getImplementsList()) {
			ModuleCompilationUnit interfaceCU = getHostProgram().lookupModuleCUNoTransform(ma);
			if (ma == null) { //should have already been handled in CheckModuleDecls
				continue;
			}
			for (String packageName : interfaceCU.getExportedPackages()) {
				if (getLocalPackageWithSuper(packageName) == null) {
					ma.error("Implemented module interface " + 
						interfaceCU.getModuleName() + 
						" exports package " + 
						packageName + 
						" but is not present in module " + 
						this.getModuleName());
				} else if (!(getLocalPackageWithSuper(packageName).isExported())){
					ma.error("Implemented module interface " + 
						interfaceCU.getModuleName() + 
						" exports package " + 
						packageName + 
						" but is not exported in module " + 
						this.getModuleName());
				}
			}
		}
	}
}