[patch] Add libstdc++ type printers for class templates

[Jonathan Wakely]

This defines a new style of Python type printer that recognizes
templates and can be used to omit default template arguments from the
typename GDB prints, e.g. showing std::vector<T, std::allocator<T>> as
simply std::vector<T>.  Additionally, T will get processed by the type
recognizers so if it's a standard typedef or template it will also get
displayed in its abbreviated form.

e.g. with current trunk:

Breakpoint 1, main () at p.cc:45
45        std::vector<std::deque<std::list<int>>> nested;
(gdb) whatis nested
type = std::vector<std::deque<std::list<int, std::allocator<int> >, std::allocator<std::list<int, std::allocator<int> > > >, std::allocator<std::deque<std::list<int, std::allocator<int> >, std::allocator<std::list<int, std::allocator<int> > > > > >

and with this patch:

(gdb) whatis nested
type = std::vector<std::deque<std::list<int>>>

N.B. I am not printing spaces between the closing angle brackets. If
people prefer I can put them in, or only do it for C++11 types, so
that copying and pasting types from GDB will always work (if you're
copying a C++11 type then you must be planning to use it with a C++11
compiler, which will handle >> without spaces).

This passes the python testsuite but I'll wait for comments before
committing, in case my use of the GDB API or Python can be improved by
anyone.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: patch.txt
Type: text/x-patch
Size: 8650 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20140714/be9c30fb/attachment.bin>