[PATCH] -var-update [was Re: Variable objects: references formatting]

[Nick Roberts <nickrob at snap dot net dot nz>]

 > > However, do you see the problem with references that I mentioned earlier
 > > (that they don't seem to disappear from the changelist with -var-update)?
 > > This seems to be the case for any variable object made from a reference.
 > 
 > Yes, I see that for variable object created from reference, -var-update * 
 > always mentions that. Looking at this under debugger, it seems that the call 
 > to my_value_equal in varobj_update compares the value of *reference* to the 
 > value of new *referenced-to* object. This happens in my_value_equal 
 > (varobj.c):
 >
 >  static int
 >  my_value_equal (struct value *val1, struct value *volatile val2, int
 >   *error2)
 > ...

 >   ...Alas, quick attempt to do that results in segfault, and I'm out of 
 > time for today. Feel free to beat me to it ;-)

I think this patch works.  My reasoning is one of symmetry: whatever is done to
val2 should also be done to val1, and that you probably don't want to change
the contents of val1 (hence val3).  I don't know exactly what coerce_array
does, apart from convert the type from TYPE_CODE_REF to TYPE_CODE_INT or
TYPE_CODE_FLOAT or whatever, so the comment might not be quite right.

AFAICS it introduces no new fails into the testsuite.  Then again there
are no tests for references, so I guess a new one would be appropriate


-- 
Nick                                           http://www.inet.net.nz/~nickrob



2006-05-09  Nick Roberts  <nickrob@snap.net.nz>

	* varobj.c (my_value_equal): Make it work for references.


*** varobj.c	04 May 2006 22:11:38 +1200	1.60
--- varobj.c	09 May 2006 00:08:55 +1200	
***************
*** 1460,1465 ****
--- 1460,1466 ----
  my_value_equal (struct value *val1, struct value *volatile val2, int *error2)
  {
    volatile struct gdb_exception except;
+   struct value *val3;
  
    /* As a special case, if both are null, we say they're equal.  */
    if (val1 == NULL && val2 == NULL)
***************
*** 1470,1475 ****
--- 1471,1479 ----
    /* The contents of VAL1 are supposed to be known.  */
    gdb_assert (!value_lazy (val1));
  
+   /* Make sure we get the contents of VAL1.  */
+   val3 = coerce_array (val1);
+ 
    /* Make sure we also know the contents of VAL2.  */
    val2 = coerce_array (val2);
    TRY_CATCH (except, RETURN_MASK_ERROR)
***************
*** 1484,1490 ****
      }
    gdb_assert (!value_lazy (val2));
  
!   return value_contents_equal (val1, val2);
  }
  
  /* FIXME: The following should be generic for any pointer */
--- 1488,1494 ----
      }
    gdb_assert (!value_lazy (val2));
  
!   return value_contents_equal (val3, val2);
  }
  
  /* FIXME: The following should be generic for any pointer */