hash policy patch

[Paolo Carlini]

Hi,
>     Looks like there is an unexpected bad_alloc exception. The test 
> expect one to be generated when the max load factor is set to a very 
> small value 0.001 but not in any other place. To do so I used the 
> testsuite __gnu_test::set_memory_limits method and I just discover 
> that AFAIC see this new test is the first one to use this feature ! It 
> is documented this way in testsuite_hooks.h:
>
> // 2)  set_memory_limits()
> //   set_memory_limits() uses setrlimit() to restrict dynamic memory
> //   allocation.  We provide a default memory limit if none is passed 
> by the
> //   calling application.  The argument to set_memory_limits() is the
> //   limit in megabytes (a floating-point number).  If 
> _GLIBCXX_RES_LIMITS is
> //   not #defined before including this header, then no limiting is 
> attempted.
>
>     To define _GLIBCXX_RES_LIMITS for the test I use a:
>
> // { dg-options "-std=gnu++0x -D_GLIBCXX_RES_LIMITS" }
>
>     But in fact defining _GLIBCXX_RES_LIMITS when including this 
> header is not enough and is even rather useless. This  macro is also 
> used in testsuite_hooks.cc so it must be defined when this translation 
> unit is built.  So could you try to run the test again with this command:
>
> make CXXFLAGS=-D_GLIBCXX_RES_LIMITS check
Actually, I don't think this is the way to go, I'm sorry to not have 
noticed that earlier. Normally, see, eg, locale/cons/12438.cc, we just 
call __gnu_test::set_memory_limits, I blindly assumed you followed the 
existing practice.

I can try to run the patch + testcases with the -D_GLIBCXX_RES_LIMITS 
removed, but please, in general, be careful to allow for a range of 
different system, we can't be too strict, generically.

Paolo.