On 04/11/2024 19:45, Jonathan Wakely wrote:
On Mon, 4 Nov 2024 at 18:30, François Dumont <frs.dum...@gmail.com> wrote:
On 21/10/2024 06:56, François Dumont wrote:
On 17/10/2024 23:11, Jonathan Wakely wrote:
On Thu, 17 Oct 2024 at 21:39, Jonathan Wakely <jwakely....@gmail.com> wrote:
On Thu, 17 Oct 2024 at 20:52, François Dumont <frs.dum...@gmail.com> wrote:
Here is an updated version that compiles, I think, all your feedbacks. It's
much cleaner indeed.
Thanks, I'll take a look tomorrow.
It's also tested in C++98/17/23.
I'm surprised that we do not need to consider potential
allocator::const_pointer.
Do you mean consider the case where Alloc::const_pointer is not the same type
as rebinding 'pointer' to a const element type?
Yes, exactly.
We don't need to consider that because we never get a 'const_pointer' from the
allocator, and we never need to pass a 'const_pointer' to the allocator. The
allocator's 'allocate' and 'deallocate' members both work with the 'pointer' type, so
we only need to use that type when interacting with the allocator. For all the other
uses, such as _Const_Node_ptr, what we need is a pointer-to-const that's compatible
with the allocator's pointer type. It doesn't actually matter if it's the same type
as allocator_traits<Alloc>::const_pointer, because we don't need
Sorry, I sent the email before finishing that thought!
... we don't need to pass a const_pointer to anything, we only need it for the
container's own purposes.
But thinking about it some more, do we even need a const-pointer for the
container? Currently the const_iterator stores a const-pointer, and some
members like _M_root() and _M_leftmost() return a const-pointer. But they don't
need to. The nodes are all pointed to by a non-const _Base_ptr, none of the
storage managed by the container is const.
Except _M_impl._M_header in a const context.
Using const_cast would result in a similar UB that you fixed on _GLIBCXX_DEBUG
containers, no ?
We only use a pointer to _M_header for the past-the-end iterator,
which is not dereferenceable. It's OK to do the const_cast, it's not
OK to write something through that pointer/reference if the object is
really const. But you can't write through a past-the-end pointer
anyway.
One last question then to complete this work, is it fine to change
_Rb_tree_const_iterator::_M_node to _Base_ptr ? No abi issue in doing so ?
