Re: gdb_assert will never be triggered

[Joel Brobecker <brobecker@gnat.com>]

> >It looks like the assertion will always be true, due to the block
> >above... Do we want to keep this gdb_assert() call nonetheless?
> 
> Yes.  Can you post the snipped comments (both of them :-).

Here is everything:

<<
  /* Return the inner-most frame, when the caller passes in NULL.  */
  /* NOTE: cagney/2002-11-09: Not sure how this would happen.  The
     caller should have previously obtained a valid frame using
     get_selected_frame() and then called this code - only possibility
     I can think of is code behaving badly.

     NOTE: cagney/2003-01-10: Talk about code behaving badly.  Check
     block_innermost_frame().  It does the sequence: frame = NULL;
     while (1) { frame = get_prev_frame (frame); .... }.  Ulgh!  Why
     it couldn't be written better, I don't know.

     NOTE: cagney/2003-01-11: I suspect what is happening in
     block_innermost_frame() is, when the target has no state
     (registers, memory, ...), it is still calling this function.  The
     assumption being that this function will return NULL indicating
     that a frame isn't possible, rather than checking that the target
     has state and then calling get_current_frame() and
     get_prev_frame().  This is a guess mind.  */
  if (this_frame == NULL)
    {
      /* NOTE: cagney/2002-11-09: There was a code segment here that
         would error out when CURRENT_FRAME was NULL.  The comment
         that went with it made the claim ...

         ``This screws value_of_variable, which just wants a nice
         clean NULL return from block_innermost_frame if there are no
         frames.  I don't think I've ever seen this message happen
         otherwise.  And returning NULL here is a perfectly legitimate
         thing to do.''

         Per the above, this code shouldn't even be called with a NULL
         THIS_FRAME.  */
      frame_debug_got_null_frame (gdb_stdlog, this_frame, "this_frame NULL");
      return current_frame;
    }

  /* There is always a frame.  If this assertion fails, suspect that
     something should be calling get_selected_frame() or
     get_current_frame().  */
  gdb_assert (this_frame != NULL);
>>

-- 
Joel