Pretty printers for maps throwing a type error

Question

I've configured pretty printers using http://wiki.eclipse.org/CDT/User/FAQ#How_can_I_inspect_the_contents_of_STL_containers.3F. It successfully works for vector and other containers. However I can't get to inspect maps as in the example below:

#include <map>
#include <iostream>

using namespace std;

int main ()
{
map <int, string> mapIntToString;
map <int, int> mapInt2;
 mapIntToString.insert (map <int, string>::value_type (3, "Three"));
 mapInt2.insert (map <int, int>::value_type (3, 4));
 return 0;
}

I get the following error when printing using gdb:

(gdb) p mapInt2
$1 = std::map with 1 elementsTraceback (most recent call last):
File "/home/myuser/opt/gdb_printers/python/libstdcxx/v6/printers.py", line 422, in    children
rep_type = find_type(self.val.type, '_Rep_type')
File "/home/myuser/opt/gdb_printers/python/libstdcxx/v6/printers.py", line 45, in    find_type
 raise ValueError, "Cannot find type %s::%s" % (str(orig), name)
ValueError: Cannot find type std::map<int, int, std::less<int>, std::allocator<std::pair<int const, int> > >::_Rep_type

Answer 1

What compiler (and which version) did you use to build your test source?

I am guessing it wasn't a recent version of g++. Here is what I get with g++ 4.4.3-4ubuntu5:

$ gdb -q ./a.out
Reading symbols from /tmp/a.out...done.
(gdb) b 12   
Breakpoint 1 at 0x400de3: file t.cc, line 12.
(gdb) r

Breakpoint 1, main () at t.cc:12
12   return 0;
(gdb) p mapInt2
$1 = std::map with 1 elements = {[3] = 4}

Update:

This is what I get for the version: g++ (Ubuntu 4.4.3-4ubuntu5) 4.4.3

I see the problem. The instructions you've referenced are incorrect.

In particular, the instructions suggest: svn co svn://gcc.gnu.org/svn/gcc/trunk/libstdc++-v3/python, but the problem is that the python code reaches into libstdc++ internals, and therefore must match these internals (this is the reason the pretty printers are part of GCC and not part of GDB, a fact bruce.banner complained about).

When you did a fresh svn co ..., you picked up a copy of python code that no longer matches your libstdc++ internals, and that's what is causing you problems.

In particular, svn log shows that find_type was added here:

r183732 | tromey | 2012-01-30 08:25:11 -0800 (Mon, 30 Jan 2012) | 27 lines

That's much later than gcc-4.4.3. What you want to do then, is to get pretty printers that match your version of libstdc++, like so:

svn co svn://gcc.gnu.org/svn/gcc/branches/gcc_4_4_3_release/libstdc++-v3/python

Except above command will not work, because gcc 4.4.3 predates the pretty printers.

No matter, the implementation of std::map (and much of the rest of STL internals) has not changed between 4.4.3 and 4.6, and this command does work:

 svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch/libstdc++-v3/python