RFC: add a testsuite for libstdc++ pretty-printers

[Jonathan Wakely]

On 26 January 2011 21:32, Tom Tromey wrote:
> This patch adds a minimal test suite for the libstdc++ pretty-printers.
>
> I based it on Alexandre's gcc-gdb-test.exp code from the gcc test suite.
> However, I needed somewhat different functionality, so I modified it in
> a few ways.
>
> Adding a new test is very simple: modify simple.cc and add a dg-final
> marker to pretty-print the relevant objects.
>
> Let me know what you think.

I'm not competent to review the code, but I'm very pleased to see a
way to test the printers.  I've been concerned about them bitrotting
if we change library internals and forget to change the printers.
This should also help us notice if we rely on features of a particular
version of python or gdb which fail with earlier versions, e.g. python
2.6 conditional expressions and gdb 7.1 lazy strings.