Re: Patch: stl_vector.h

[Paolo Carlini <pcarlini at suse dot de>]

Dhruv Matani wrote:

> http://groups.google.co.in/groups?q=vector+constructor+author:gabriel...
>  
Ok. We should thank Gaby for this explanation.

Anyway, the basic example, not involving user allocators, still works.

On the other hand:

/usr/local/gcc-exp/lib/gcc/i686-pc-linux-gnu/4.0.0/../../../../include/c++/4.0.0/bits/stl_uninitialized.h:294: 
error: no matching function for call to 
'__gnu_cxx::__mt_alloc<dvector_t, __gnu_cxx::__common_pool_policy<true> 
>::construct(dvector_t*, const int&)'
/usr/local/gcc-exp/lib/gcc/i686-pc-linux-gnu/4.0.0/../../../../include/c++/4.0.0/ext/mt_allocator.h:613: 
note: candidates are: void 
__gnu_cxx::__mt_alloc_base<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = 
dvector_t]

This is, actually, *another* issue and indeed happens because now (after 
Matt's changes
this summer) the user-provided allocator is used throughout.

I'm not at all convinced that in _M_initialize_dispatch(__true_type) we 
should always
cast __value (an integer) to value_type (that is, in the example, a 
dvector_t). Honestly,
I'm under the impression that we are slightly abusing those overloads...

I think we should ask Matt, in the first place: he is """guilty""" of 
this """regression"""...

Matt, should this testcase compile:

#include <vector>
#include <ext/pool_allocator.h>

using __gnu_cxx::__pool_alloc;

typedef std::vector<double, __pool_alloc<double> > dvector_t;
typedef std::vector<dvector_t, __pool_alloc<dvector_t> > matrix_t;

matrix_t m = matrix_t(1, 1);

???

Thanks,
Paolo.