[RFA] Allow casting of object pointers for method calls

[Daniel Jacobowitz <drow at mvista dot com>]

I'd like to commit this.

>From the comment on value_virtual_fn_field:
   VALUEP is a pointer to a pointer to a value, holding the object
   whose virtual function we want to invoke.  If the ABI requires a
   virtual function's caller to adjust the `this' pointer by an amount
   retrieved from the vtable before invoking the function (i.e., we're
   not using "vtable thunks" to do the adjustment automatically), then
   this function may set *VALUEP to point to a new object with an
   appropriately tweaked address.

find_overload_match went out of its way to prevent this from working.  The
cast at the end is unpleasant but, as far as I can see, correct;
value_find_oload_method_list tends to dereference pointers, and if we don't
return this rather than *this things die.

With this patch, all virtfunc tests other than:
XFAIL: gdb.c++/virtfunc.exp: print pEe->D::vg()

pass using g++ 2.95.  No other regressions.  I'll submit a separate patch to
remove their XFAILs.  This is also necessary for my g++ 3.0 support stuff,
which is pretty trivial after Jason's gcc work and this values patchs.

Anyone, comments?  I think the hack is (for now at least, maybe with a
FIXME) tolerable.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer

2001-12-03  Daniel Jacobowitz  <drow@mvista.com>

	* valops.c (find_overload_match): Accept obj as a
	reference parameter.  Update it before returning.
	* value.h (find_overload_match): Update prototype.
	* eval.c (evaluate_subexp_standard): Pass object to
	find_overload_match by reference.

Index: eval.c
===================================================================
RCS file: /cvs/src/src/gdb/eval.c,v
retrieving revision 1.16
diff -u -p -r1.16 eval.c
--- eval.c	2001/11/12 21:20:18	1.16
+++ eval.c	2001/12/03 15:27:58
@@ -845,7 +845,7 @@ evaluate_subexp_standard (struct type *e
 
 	      (void) find_overload_match (arg_types, nargs, tstr,
 				     1 /* method */ , 0 /* strict match */ ,
-					  arg2 /* the object */ , NULL,
+					  &arg2 /* the object */ , NULL,
 					  &valp, NULL, &static_memfuncp);
 
 
Index: valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.41
diff -u -p -r1.41 valops.c
--- valops.c	2001/11/13 16:44:13	1.41
+++ valops.c	2001/12/03 15:27:58
@@ -2618,12 +2618,13 @@ value_find_oload_method_list (value_ptr 
 
 int
 find_overload_match (struct type **arg_types, int nargs, char *name, int method,
-		     int lax, value_ptr obj, struct symbol *fsym,
+		     int lax, value_ptr *objp, struct symbol *fsym,
 		     value_ptr *valp, struct symbol **symp, int *staticp)
 {
   int nparms;
   struct type **parm_types;
   int champ_nparms = 0;
+  struct value *obj = (objp ? *objp : NULL);
 
   short oload_champ = -1;	/* Index of best overloaded function */
   short oload_ambiguous = 0;	/* Current ambiguity state for overload resolution */
@@ -2847,6 +2848,15 @@ find_overload_match (struct type **arg_t
       xfree (func_name);
     }
 
+  if (objp)
+    {
+      if (TYPE_CODE (VALUE_TYPE (temp)) != TYPE_CODE_PTR
+	  && TYPE_CODE (VALUE_TYPE (*objp)) == TYPE_CODE_PTR)
+	{
+	  temp = value_addr (temp);
+	}
+      *objp = temp;
+    }
   return oload_incompatible ? 100 : (oload_non_standard ? 10 : 0);
 }
 
Index: value.h
===================================================================
RCS file: /cvs/src/src/gdb/value.h,v
retrieving revision 1.22
diff -u -p -r1.22 value.h
--- value.h	2001/10/16 01:58:07	1.22
+++ value.h	2001/12/03 15:27:58
@@ -386,7 +386,7 @@ extern struct fn_field *value_find_oload
 
 extern int find_overload_match (struct type **arg_types, int nargs,
 				char *name, int method, int lax,
-				value_ptr obj, struct symbol *fsym,
+				value_ptr *obj, struct symbol *fsym,
 				value_ptr * valp, struct symbol **symp,
 				int *staticp);