Re: testsuite allocators patch

[Jonathan Wakely <jwakely at redhat dot com>]

On 25/06/14 21:47 +0200, François Dumont wrote:
> >    I would like to finally propose this patch before the one on 
> > _Rb_tree, as a separate one.
> >
> >    I have adopted the same evolution on the tracker_allocator with 
> > even a perfect forwarding constructor to allow its usage on top of 
> > the uneq_allocator  which take a personality parameter. Doing so I 
> > realized that move_assign_neg.cc tests were not accurate enough as 
> > they needed a non move propagating allocator and the uneq_allocator 
> > were not explicitly non propagating.

Ah, that's good to improve them then.

> Index: testsuite/util/testsuite_allocator.h
> ===================================================================
> --- testsuite/util/testsuite_allocator.h	(revision 211713)
> +++ testsuite/util/testsuite_allocator.h	(working copy)
> @@ -87,103 +81,142 @@
>     static int        destructCount_;
>   };
>
> -  // A simple basic allocator that just forwards to the
> +  // Helper to detect inconsistency between type used to instantiate an
> +  // allocator and the underlying allocator value_type.
> +  template<typename T, typename Alloc,
> +	   typename = typename Alloc::value_type>
> +    struct check_consistent_alloc_value_type;
> +
> +  template<typename T, typename Alloc>
> +    struct check_consistent_alloc_value_type<T, Alloc, T>
> +    { typedef T value_type; };
> +
> +  // An allocator facade that just intercepts some calls and forward them to the
>   // tracker_allocator_counter to fulfill memory requests.  This class

This comment is no longer true, tracker_allocator_counter does not
fulfil the memory requests.

>   // is templated on the target object type, but tracker isn't.
> -  template<class T>
> -  class tracker_allocator
> -  {
> -  private:
> -    typedef tracker_allocator_counter counter_type;
> +  template<typename T, typename Alloc = std::allocator<T> >
> +    class tracker_allocator : public Alloc
> +    {
> +    private:
> +      typedef tracker_allocator_counter counter_type;
>
> -  public:
> -    typedef T              value_type;
> -    typedef T*             pointer;
> -    typedef const T*       const_pointer;
> -    typedef T&             reference;
> -    typedef const T&       const_reference;
> -    typedef std::size_t    size_type; 
> -    typedef std::ptrdiff_t difference_type; 
> +      typedef __gnu_cxx::__alloc_traits<Alloc> AllocTraits;
> +
> +    public:
> +      typedef typename
> +      check_consistent_alloc_value_type<T, Alloc>::value_type value_type;
> +      typedef typename AllocTraits::pointer pointer;
> +      typedef typename AllocTraits::size_type size_type;

Thanks for doing this - I think it makes the facade more useful if it
uses allocator_traits and so can be combined with SimpleAllocator and
CustomPointerAlloc.

> -    template<class U> struct rebind { typedef tracker_allocator<U> other; };
> +      template<class U>
> +	struct rebind
> +	{
> +	  typedef tracker_allocator<U,
> +		typename AllocTraits::template rebind<U>::other> other;
> +	};
>     
> -    pointer
> -    address(reference value) const _GLIBCXX_NOEXCEPT
> -    { return std::__addressof(value); }
> +#if __cplusplus >= 201103L
> +      tracker_allocator() = default;
> +      tracker_allocator(const tracker_allocator&) = default;
> +      tracker_allocator(tracker_allocator&&) = default;
>
> -    const_pointer
> -    address(const_reference value) const _GLIBCXX_NOEXCEPT
> -    { return std::__addressof(value); }
> +      // Perfect forwarding constructor.
> +      template<typename... _Args>
> +	tracker_allocator(_Args&&... __args)
> +	  : Alloc(std::forward<_Args>(__args)...)
> +	{ }
> +#else
> +      tracker_allocator() _GLIBCXX_USE_NOEXCEPT

The _GLIBCXX_USE_NOEXCEPT macro expands to nothing in C++03 mode, so
you might as well omit it in the #else branch.

OK for trunk if you make the tracker_allocator comment correct.

Thanks!