Move semantic dosn't work with eastl::list

[SGTech87]

There is a move semantic problem at the eastl::list, which is the as issue as it was with the eastl::vector: Cannot move assign a eastl::vector<unique_ptr> #56

The solution works, but in case of different allocators an error message would be preferable.

[jhopkins-ea]

Thanks for bringing this up and sharing the related issue.

In our internal version of EASTL I recently added tests for allocator propagation because we don't have documentation on the allocator propagation behaviour (see propagate_on_X types from AllocatorAwareContainer). EASTL doesn't have the allocator traits class and instead has the same propagation behaviour for all allocators. The results of my testing were:

• propagate_on_container_copy_assignment::value is equivalent to the EASTL_ALLOCATOR_COPY_ENABLED macro (defaults to false).
• propagate_on_container_move_assignment::value is always true.
• propagate_on_container_swap::value is always true.

Of note, and directly related to your issue is that both list and slist (forward_list) have inconsistent propagation behaviour to the rest of EASTL. Additionally, basic_string also has inconsistent behaviour. Before I can submit a fix I need to do some testing to make sure that EA code is not relying on the current incorrect behaviour for those types. It may be some time before I get to that work.

[jhopkins-ea]

For reference / visibility the reproducible example, causing compilation error, is:

eastl::list<eastl::unique_ptr<int>> l1;
eastl::list<eastl::unique_ptr<int>> l2;
l1 = eastl::move(l2);

Same for slist.