Fix gdb_pretty_printer_test on python3

[zatrazz]

Summary

First issue is the 'next' iteration method which has changed its
name to '_next_'. The another is the division method, where it
requires to use the floor division so iteration converge.

[saugustine]

Thanks so much for fixing this. Really appreciate it.

[zatrazz]

In D67733#1674557, @saugustine wrote:

Thanks so much for fixing this. Really appreciate it.

In fact this is fully correct for python2, I will need to update this patch.

[zatrazz]

I checked it with a gdb built against python 2.7.2 and python 3.7.4. I still seeing some issue on the arm bot, but I think it is unrelated to the python3 support now.

libcxx/test/pretty_printers/gdb_pretty_printer_test.py

 from __future__ import print_function
 import re
 import gdb
+import sys
+
+if sys.version_info >= (3, 0):
+    py3k = True
+else:
+    py3k = False
+
 
 test_failures = 0
 

                 check_literal = expectation_val.string()
                 test_fails = not re.match(check_literal, value)
             else:
-                check_literal_string = expectation_val.string(encoding="utf-8")
-                check_literal = check_literal_string.encode("utf-8")
+                if not py3k:
+                     check_literal_string = expectation_val.string(encoding="utf-8")
+                     check_literal = check_literal_string.encode("utf-8")
+                else:
+                     check_literal = expectation_val.string(encoding="utf-8")
                 test_fails = value != check_literal
 
             if test_fails:

libcxx/utils/gdb/libcxx/printers.py

 
 import re
 import gdb
+import sys
+
+if sys.version_info >= (3, 0):
+    py3k = True
+else:
+    py3k = False
 
 # One under-documented feature of the gdb pretty-printer API
 # is that clients can call any other member of the API

         def __iter__(self):
             return self
 
-        def next(self):
+        def __next__(self):
             # child_iter raises StopIteration when appropriate.
-            field_name = self.child_iter.next()
+            if not py3k:
+                 field_name = self.child_iter.next()
+            else:
+                 field_name = self.child_iter.__next__()
             child = self.val["__base_"][field_name]["__value_"]
             self.count += 1
             return ("[%d]" % self.count, child)
 
+        if not py3k:
+            next = __next__
+
     def __init__(self, val):
         self.val = val
 

         def __iter__(self):
             return self
 
-        def next(self):
+        def __next__(self):
             """Retrieve the next element."""
 
             self.count += 1

                 self.offset = 0
             return ("[%d]" % self.count, outbit)
 
+        if not py3k:
+            next = __next__
+
     class _VectorIterator(object):
         """Class to iterate over the non-bool vector's children."""
 

         def __iter__(self):
             return self
 
-        def next(self):
+        def __next__(self):
             self.count += 1
             if self.item == self.end:
                 raise StopIteration

             self.item += 1
             return ("[%d]" % self.count, entry)
 
+        if not py3k:
+            next = __next__
+
     def __init__(self, val):
         """Set val, length, capacity, and iterator for bool and normal vectors."""
         self.val = val

         while value:
             index += 1
             will_yield = value % 2
-            value /= 2
+            value //= 2
             if will_yield:
                 yield index