ddd bug ?

[Konstantin]

  A simple case. (OS: FC3_x64, compiler is native (gcc 3.4.2)).
  I make a f77 program, say, tmp.F:

      program tmp
      print *, Hello
      end

  Then, I compile it:

    g77 -c -g tmp.F

and open the object file tmp.o in gdb or ddd. In gdb source can't be seen 
("list tmp.F:1" -> "No source file tmp.F"),
but in ddd I do see source, but in addition to tmp.F there is one more file 
/tmp/ccwmF4Ox.f, that ddd tries to open but
can't (it doesn't exist actually).
   Could anyone explain or comment the situation. Is this a problem of gdb or 
gcc?

   Thanks in advance.

   Konstantin.