From patchwork Thu Dec 22 12:44:39 2011
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Subject: [v3] libstdc++/48362 - pretty printer for std::tuple<> with no
 elements
From: Jonathan Wakely <jwakely.gcc@gmail.com>
X-Patchwork-Id: 132841
Message-Id: <CAH6eHdQpCucX6x6ZpHBH3ihk35NjvDw5umMNR0c-GAEHn4mzzQ@mail.gmail.com>
To: "libstdc++" <libstdc++@gcc.gnu.org>, gcc-patches <gcc-patches@gcc.gnu.org>
Date: Thu, 22 Dec 2011 12:44:39 +0000

PR libstdc++/48362
        * python/libstdcxx/v6/printers.py (StdTuplePrinter): Handle empty
        tuples.

There might be a neater way to fix this, but this does the job.

Committed to trunk.


Index: python/libstdcxx/v6/printers.py
===================================================================
--- python/libstdcxx/v6/printers.py	(revision 182619)
+++ python/libstdcxx/v6/printers.py	(revision 182620)
@@ -251,11 +251,11 @@ class StdTuplePrinter:
             # Set the base class as the initial head of the
             # tuple.
             nodes = self.head.type.fields ()
-            if len (nodes) != 1:
+            if len (nodes) == 1:
+                # Set the actual head to the first pair.
+                self.head  = self.head.cast (nodes[0].type)
+            elif len (nodes) != 0:
                 raise ValueError, "Top of tuple tree does not consist of a single node."
-
-            # Set the actual head to the first pair.
-            self.head  = self.head.cast (nodes[0].type)
             self.count = 0
 
         def __iter__ (self):
@@ -297,6 +297,8 @@ class StdTuplePrinter:
         return self._iterator (self.val)
 
     def to_string (self):
+        if len (self.val.type.fields ()) == 0:
+            return 'empty %s' % (self.typename)
         return '%s containing' % (self.typename)
 
 class StdStackOrQueuePrinter: