>> -	 (sym (concat (symbol-name tag) "@" file))
>> +	 (sym (concat (symbol-name tag) "@"
>> +                      (if (file-name-absolute-p file)
>> +                          file
>> +                        (expand-file-name file))))
>
> (cons tag (if (file-name-absolute-p file) file (expand-file-name file)))
>
> is more efficient.
>

I don't see a performance impact in my tests, but I'll trust the master.