Re: GDB and C++: handling of POD/non-POD objects

[Christophe LYON <christophe dot lyon at st dot com>]

> > Here's a patch; I haven't updated or tested it in a while.  I need to
> > rework it, and I need to check a couple of existing disabled tests that
> > it probably affects; I just haven't had the time yet.
> >

I have managed to include your patch in our gdb-6.1 source tree.

However, I had to remove parts of the infcall.c patch, namely:
+  if (cp_struct_return)
+    {
+      struct value **new_args;
+
+      /* Add the new argument to the front of the argument list.  */
+      new_args = xmalloc (sizeof (struct value *) * (nargs + 1));
+      new_args[0] = value_from_pointer (lookup_pointer_type
(value_type),
+                                       struct_addr);
+      memcpy (&new_args[1], &args[0], sizeof (struct value *) * nargs);
+      args = new_args;
+      nargs++;
+      args_cleanup = make_cleanup (xfree, args);
+    }
+  else
+    args_cleanup = make_cleanup (null_cleanup, NULL);

(along with the declaration and cleanup of args_cleanup)

Indeed, for our target, the pointer to the memory area reserved
to hold the return value is passed as a hidden pointer, before
'this', but it does not make all the parameters shift.

>From what I found in the C++ abi, 3.1.4, the return value is
passed in an implicit hidden pointer, so I guess we are right,
and the code above is incorrect.


Finally, I have not yet taken time to add true tests to the empty
pass-by-ref.exp you supplied.


Thanks for you help,

Christophe