libstdc++:: improve how pretty printers find node types (PR 91997)

This fixes two related problems.

The iterators for node-based containers use nested typedefs such as
std::list<T>::iterator::_Node to denote their node types. As reported in
https://bugzilla.redhat.com/show_bug.cgi?id=1053438 those typedefs are
not always present in the debug info. That means the pretty printers
cannot find them using gdb.lookup_type (via the find_type helper).
Instead of looking up the nested typedefs this patch makes the printers
look up the actual class templates directly.

A related problem (and the original topic of PR 91997) is that GDB fails
to find types via gdb.lookup_type when printing a backtrace from a
non-C++ functiion: https://sourceware.org/bugzilla/show_bug.cgi?id=25234
That is also solved by not looking up the nested typedef.

	PR libstdc++/91997
	* python/libstdcxx/v6/printers.py (find_type): Fail more gracefully
	if we run out of base classes to look at.
	(llokup_templ_spec, lookup_node_type): New utilities to find node
	types for node-based containers.
	(StdListPrinter.children, NodeIteratorPrinter.__init__)
	(NodeIteratorPrinter.to_string, StdSlistPrinter.children)
	(StdSlistIteratorPrinter.to_string, StdRbtreeIteratorPrinter.__init__)
	(StdMapPrinter.children, StdSetPrinter.children)
	(StdForwardListPrinter.children): Use lookup_node_type instead of
	find_type.
	(StdListIteratorPrinter.__init__, StdFwdListIteratorPrinter.__init__):
	Pass name of node type to NodeIteratorPrinter constructor.
	(Tr1HashtableIterator.__init__): Rename argument.
	(StdHashtableIterator.__init__): Likewise. Use lookup_templ_spec
	instead of find_type.
	* testsuite/libstdc++-prettyprinters/59161.cc: Remove workaround for
	_Node typedef not being present in debuginfo.
	* testsuite/libstdc++-prettyprinters/91997.cc: New test.

From-SVN: r278846

libstdc++-v3/ChangeLog

+2019-11-29  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/91997
+	* python/libstdcxx/v6/printers.py (find_type): Fail more gracefully
+	if we run out of base classes to look at.
+	(llokup_templ_spec, lookup_node_type): New utilities to find node
+	types for node-based containers.
+	(StdListPrinter.children, NodeIteratorPrinter.__init__)
+	(NodeIteratorPrinter.to_string, StdSlistPrinter.children)
+	(StdSlistIteratorPrinter.to_string, StdRbtreeIteratorPrinter.__init__)
+	(StdMapPrinter.children, StdSetPrinter.children)
+	(StdForwardListPrinter.children): Use lookup_node_type instead of
+	find_type.
+	(StdListIteratorPrinter.__init__, StdFwdListIteratorPrinter.__init__):
+	Pass name of node type to NodeIteratorPrinter constructor.
+	(Tr1HashtableIterator.__init__): Rename argument.
+	(StdHashtableIterator.__init__): Likewise. Use lookup_templ_spec
+	instead of find_type.
+	* testsuite/libstdc++-prettyprinters/59161.cc: Remove workaround for
+	_Node typedef not being present in debuginfo.
+	* testsuite/libstdc++-prettyprinters/91997.cc: New test.
+
 2019-11-26  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/debug/helper_functions.h (__valid_range_aux): Use C++98

libstdc++-v3/testsuite/libstdc++-prettyprinters/59161.cc

@@ -45,8 +45,6 @@ int main()
   std::list<C> l;
   l.push_back(c);
   std::list<C>::iterator liter = l.begin();
-  // Need to ensure the list<C>::iterator::_Node typedef is in the debuginfo:
-  int tmp __attribute__((unused)) = (*liter).ref;
 // { dg-final { regexp-test liter {ref = @0x.*} } }
 
   __gnu_cxx::slist<C> sl;

libstdc++-v3/testsuite/libstdc++-prettyprinters/91997.cc

+// { dg-options "-std=gnu++17 -g -O0 -Wno-unused" }
+// { dg-do run { target c++17 } }
+
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library 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, or (at your option)
+// any later version.
+
+// This library 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 library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <forward_list>
+#include <list>
+#include <set>
+#include <map>
+#include <string>
+#include <any>
+#include <iostream>
+
+int main()
+{
+  std::list<std::string> list{"a"};
+  std::list<std::string>::iterator lit = list.begin();
+  // { dg-final { note-test lit {"a"} } }
+
+  std::forward_list<std::string> flist{"b"};
+  std::forward_list<std::string>::iterator flit = flist.begin();
+  // { dg-final { note-test flit {"b"} } }
+
+  std::map<int, int> m{ {1, 2} };
+  auto mit = m.begin();
+  // { dg-final { note-test mit {{first = 1, second = 2}} } }
+
+  std::any a = m;
+  // { dg-final { note-test a {std::any containing std::map with 1 element = {[1] = 2}} } }
+
+  std::set<int> s{1, 2};
+  auto sit = s.begin();
+  // { dg-final { note-test sit {1} } }
+
+  std::cout << "\n";
+  return 0;			// Mark SPOT
+}
+// { dg-final { gdb-test SPOT } }