def _post_save_work(self) -> None:
        """After saving data, look for warnings, post-work, etc.

        Warn about things that should have happened but didn't.
        Look for un-executed files.

        """
        assert self._data is not None
        assert self._inorout is not None

        # If there are still entries in the source_pkgs_unmatched list,
        # then we never encountered those packages.
        if self._warn_unimported_source:
            self._inorout.warn_unimported_source()

        # Find out if we got any data.
        if not self._data and self._warn_no_data:
            self._warn("No data was collected.", slug="no-data-collected")

        # Touch all the files that could have executed, so that we can
        # mark completely un-executed files as 0% covered.
        file_paths = collections.defaultdict(list)
        for file_path, plugin_name in self._inorout.find_possibly_unexecuted_files():
            file_path = self._file_mapper(file_path)
            file_paths[plugin_name].append(file_path)
        for plugin_name, paths in file_paths.items():
            self._data.touch_files(paths, plugin_name)
After saving data, look for warnings, post-work, etc.

        Warn about things that should have happened but didn't.
        Look for un-executed files.

        
coverage/control.py