PR python/18089

gdb/ChangeLog:

	PR python/18089
	* python/py-prettyprint.c (print_children): Verify result of children
	iterator.  Provide better error message.
	* python/python-internal..h (gdbpy_print_python_errors_p): Declare.
	* python/python.c (gdbpy_print_python_errors_p): New function.

gdb/testsuite/ChangeLog:

	* gdb.python/py-bad-printers.c: New file.
	* gdb.python/py-bad-printers.py: New file.
	* gdb.python/py-bad-printers.exp: New file.

gdb/testsuite/gdb.python/py-bad-printers.py

@@ -0,0 +1,80 @@
+# Copyright (C) 2008-2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It tests GDB's handling of
+# bad python pretty printers.
+
+# Test a printer with a bad children iterator.
+
+import re
+import gdb.printing
+
+
+class BadChildrenContainerPrinter1(object):
+    """Children iterator doesn't return a tuple of two elements."""
+
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        return 'container %s with %d elements' % (self.val['name'], self.val['len'])
+
+    @staticmethod
+    def _bad_iterator(pointer, len):
+        start = pointer
+        end = pointer + len
+        while pointer != end:
+            yield 'intentional violation of children iterator protocol'
+            pointer += 1
+
+    def children(self):
+        return self._bad_iterator(self.val['elements'], self.val['len'])
+
+
+class BadChildrenContainerPrinter2(object):
+    """Children iterator returns a tuple of two elements with bad values."""
+
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        return 'container %s with %d elements' % (self.val['name'], self.val['len'])
+
+    @staticmethod
+    def _bad_iterator(pointer, len):
+        start = pointer
+        end = pointer + len
+        while pointer != end:
+            # The first argument is supposed to be a string.
+            yield (42, 'intentional violation of children iterator protocol')
+            pointer += 1
+
+    def children(self):
+        return self._bad_iterator(self.val['elements'], self.val['len'])
+
+
+def build_pretty_printer():
+    pp = gdb.printing.RegexpCollectionPrettyPrinter("bad-printers")
+
+    pp.add_printer('container1', '^container$',
+                   BadChildrenContainerPrinter1)
+    pp.add_printer('container2', '^container$',
+                   BadChildrenContainerPrinter2)
+
+    return pp
+
+
+my_pretty_printer = build_pretty_printer()
+gdb.printing.register_pretty_printer(gdb, my_pretty_printer)