Fix for PR 18470:

	* value.c (value_virtual_fn_field): Handle the situation where
	vtbl is a pointer to a structure instead of a pointer to an array.

1 files changed, 25 insertions, 9 deletions

diff --git a/gdb/values.c b/gdb/values.c
index db6f204..9ddf159 100644
--- a/gdb/values.c
+++ b/gdb/values.c
@@ -910,15 +910,31 @@ value_virtual_fn_field (arg1p, f, j, type, offset)
 
   /* The virtual function table is now an array of structures
      which have the form { int16 offset, delta; void *pfn; }.  */
-  vtbl = value_ind (value_primitive_field (arg1, 0, 
-					   TYPE_VPTR_FIELDNO (context),
-					   TYPE_VPTR_BASETYPE (context)));
-
-  /* Index into the virtual function table.  This is hard-coded because
-     looking up a field is not cheap, and it may be important to save
-     time, e.g. if the user has set a conditional breakpoint calling
-     a virtual function.  */
-  entry = value_subscript (vtbl, vi);
+  vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
+					 TYPE_VPTR_BASETYPE (context));
+
+  /* With older versions of g++, the vtbl field pointed to an array
+     of structures.  Nowadays it points directly to the structure. */
+  if (TYPE_CODE (VALUE_TYPE (vtbl)) == TYPE_CODE_PTR
+      && TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (vtbl))) == TYPE_CODE_ARRAY)
+    {
+      /* Handle the case where the vtbl field points to an
+         array of structures. */
+      vtbl = value_ind (vtbl);
+
+      /* Index into the virtual function table.  This is hard-coded because
+	 looking up a field is not cheap, and it may be important to save
+	 time, e.g. if the user has set a conditional breakpoint calling
+	 a virtual function.  */
+      entry = value_subscript (vtbl, vi);
+    }
+  else
+    {
+      /* Handle the case where the vtbl field points directly to a structure. */
+      vtbl = value_add (vtbl, vi);
+      entry = value_ind (vtbl);
+    }
+
   entry_type = check_typedef (VALUE_TYPE (entry));
 
   if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)