gdb

* valops.c (value_cast_structs): Try downcasting using the RTTI
	type.
gdb/testsuite
	* gdb.cp/virtbase.exp: Add regression tests.
	* gdb.cp/virtbase.cc (RHA, RHB, RHC): New classes.
	(main): Instantiate RHC.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2010-02-02  Tom Tromey  <tromey@redhat.com>
+
+	* valops.c (value_cast_structs): Try downcasting using the RTTI
+	type.
+
 2010-02-02  Tom Tromey  <tromey@redhat.com>
 
 	* gnu-v2-abi.c: Don't include gnu-v2-abi.h.

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2010-02-02  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.cp/virtbase.exp: Add regression tests.
+	* gdb.cp/virtbase.cc (RHA, RHB, RHC): New classes.
+	(main): Instantiate RHC.
+
 2010-02-02  Tom Tromey  <tromey@redhat.com>
 
 	* gdb.dwarf2/member-ptr-forwardref.exp: Update expected result for

gdb/testsuite/gdb.cp/virtbase.cc

@@ -46,12 +46,44 @@ struct D:virtual C{};
 
 class E:B,D{};
 
+// These classes are for another regression test, from
+// https://bugzilla.redhat.com/show_bug.cgi?id=560741
+
+class RHA
+{
+public:
+  RHA() : mA(0xaaaaaaaa) {}
+  virtual void a() = 0;  
+  int mA;
+};
+
+class RHB
+{
+public:
+  RHB() : mB(0xbbbbbbbb) {}
+  virtual void b() = 0;
+  int mB;
+};
+
+class RHC : public RHA,
+	  public RHB
+{
+public:
+  RHC() : RHA(), RHB() {}
+  virtual void a() {}
+  virtual void b() {}
+};
+
+
+
+
 int main() {
   ph::Derived tst;
   tst.get_y();
   tst.get_z();
 
   E *e = new E;
+  RHB *b = new RHC();
 
   return 0;			// breakpoint 3
 }

gdb/testsuite/gdb.cp/virtbase.exp

@@ -55,3 +55,8 @@ gdb_continue_to_breakpoint "third breakpoint"
 
 # In PR 9629, we failed to print v correctly here.
 gdb_test "print *(D *) e" " = {<C> = {v = 11}, _vptr.D = $hex}"
+
+# A regression test reported to Red Hat bugzilla, see:
+# https://bugzilla.redhat.com/show_bug.cgi?id=560741
+gdb_test "set print object on" ""
+gdb_test "print/x b->mA" " = 0xaaaaaaaa"

gdb/valops.c

@@ -250,10 +250,33 @@ value_cast_structs (struct type *type, struct value *v2)
 
   /* Downcasting: look in the type of the target to see if it contains the
      type of the source as a superclass.  If so, we'll need to
-     offset the pointer rather than just change its type.
-     FIXME: This fails silently with virtual inheritance.  */
+     offset the pointer rather than just change its type.  */
   if (TYPE_NAME (t2) != NULL)
     {
+      /* Try downcasting using the run-time type of the value.  */
+      int full, top, using_enc;
+      struct type *real_type;
+
+      real_type = value_rtti_type (v2, &full, &top, &using_enc);
+      if (real_type)
+	{
+	  v = value_full_object (v2, real_type, full, top, using_enc);
+	  v = value_at_lazy (real_type, value_address (v));
+
+	  /* We might be trying to cast to the outermost enclosing
+	     type, in which case search_struct_field won't work.  */
+	  if (TYPE_NAME (real_type) != NULL
+	      && !strcmp (TYPE_NAME (real_type), TYPE_NAME (t1)))
+	    return v;
+
+	  v = search_struct_field (type_name_no_tag (t2), v, 0, real_type, 1);
+	  if (v)
+	    return v;
+	}
+
+      /* Try downcasting using information from the destination type
+	 T2.  This wouldn't work properly for classes with virtual
+	 bases, but those were handled above.  */
       v = search_struct_field (type_name_no_tag (t2),
 			       value_zero (t1, not_lval), 0, t1, 1);
       if (v)