[python] [rfc] StdBitsetPrinter patch for printing bitsets representedby a single unsigned long.

[Phil Muldoon <pmuldoon at redhat dot com>]

The  std::bitset printer within the libstdcxx pretty-printer library has 
a bug where it assumes the data member: "_M_w" is always an array of 
data.  In some cases, the data member can be a single unsigned long. 
This patches checks and converts the single unsigned long case to a 
single element array, so the bit-extraction logic can work.

Regards

Phil

ChangeLog

2009-02-23  Phil Muldoon  <pmuldoon@redhat.com>

   * python/lib/gdb/libstdcxx/v6/printers.py
   (StdBitsetPrinter.children): Check "_M_w" for int type. If it is an
   int type, convert to array.



diff --git a/gdb/python/lib/gdb/libstdcxx/v6/printers.py b/gdb/python/lib/gdb/libstdcxx/v6/printers.py
index 701eec2..faa0d09 100644
--- a/gdb/python/lib/gdb/libstdcxx/v6/printers.py
+++ b/gdb/python/lib/gdb/libstdcxx/v6/printers.py
@@ -338,7 +338,16 @@ class StdBitsetPrinter:
     def children (self):
         words = self.val['_M_w']
         wtype = words.type()
-        tsize = wtype.target().sizeof()
+
+        # The _M_w member can be either an unsigned long, or an
+        # array.  This depends on what template type was used.  If it
+        # is a single long, convert to a single element list.
+        if wtype.code () == gdb.TYPE_CODE_ARRAY:
+            tsize = wtype.target ().sizeof ()
+        else:
+            words = [words]
+            tsize = wtype.sizeof () 
+
         nwords = wtype.sizeof() / tsize
         result = []
         byte = 0