This patch tries to improve the user experience when debugging
container iterators, for cases where some of the typedefs used by the
printers are not in the debuginfo, so gdb.lookup_type() calls fail.
That happens if the iterator's operator*() and operator->() haven't
been instantiated, or if they've been inlined.
Currently this results in an exception:
$1 = Python Exception <class 'ValueError'> Cannot find type std::_List_iterator<int>::_Node:
If the iterator being printed is part of some other object the whole
thing fails due to the exception.
With this patch the iterator instead prints:
$1 = <insufficient debuginfo for std::list iterator>
and if it's a subobject the rest of the object is printed, with that
as the value of the iterator.
* python/libstdcxx/v6/printers.py (StdListIteratorPrinter.to_string):
Handle exception from failed type lookup and return user-friendly
string.
(StdRbtreeIteratorPrinter.__init__): Handle exception from failed
type lookup.
(StdRbtreeIteratorPrinter.to_string): Return user-friendly string.
Seem reasonable?
I consider this a stop-gap until we have Xmethods for all our iterator
types, then we'll be able to "print *iter" even without debuginfo for
all the iterator's members, and we can disable these printers.
commit 1794ede023b36df4eb2c7264e2d04d6a86ad456a
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Dec 15 16:52:21 2016 +0000
Make iterator printers fail more gracefully
* python/libstdcxx/v6/printers.py (StdListIteratorPrinter.to_string):
Handle exception from failed type lookup and return user-friendly
string.
(StdRbtreeIteratorPrinter.__init__): Handle exception from failed
type lookup.
(StdRbtreeIteratorPrinter.to_string): Return user-friendly string.
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py
b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 86de1ca..60afb52 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -202,10 +202,13 @@ class StdListIteratorPrinter:
def to_string(self):
if not self.val['_M_node']:
return 'non-dereferenceable iterator for std::list'
- nodetype = find_type(self.val.type, '_Node')
- nodetype = nodetype.strip_typedefs().pointer()
- node = self.val['_M_node'].cast(nodetype).dereference()
- return str(get_value_from_list_node(node))
+ try:
+ nodetype = find_type(self.val.type, '_Node')
+ nodetype = nodetype.strip_typedefs().pointer()
+ node = self.val['_M_node'].cast(nodetype).dereference()
+ return str(get_value_from_list_node(node))
+ except:
+ return '<insufficient debuginfo for std::list iterator>'
class StdSlistPrinter:
"Print a __gnu_cxx::slist"
@@ -496,12 +499,17 @@ class StdRbtreeIteratorPrinter:
def __init__ (self, typename, val):
self.val = val
valtype = self.val.type.template_argument(0).strip_typedefs()
- nodetype = gdb.lookup_type('std::_Rb_tree_node<' + str(valtype) + '>')
- self.link_type = nodetype.strip_typedefs().pointer()
+ try:
+ nodetype = gdb.lookup_type('std::_Rb_tree_node<' + str(valtype) +
'>')
+ self.link_type = nodetype.strip_typedefs().pointer()
+ except:
+ self.link_type = None
def to_string (self):
if not self.val['_M_node']:
return 'non-dereferenceable iterator for associative container'
+ if self.link_type is None:
+ return "<insufficient debuginfo for associative container
iterator>"
node = self.val['_M_node'].cast(self.link_type).dereference()
return str(get_value_from_Rb_tree_node(node))
