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To support proper deallocation, it is required that we store allocator somewhere through the whole coroutine lifetime. Sadly, compiler does not propagate rvalue allocator no matter the type of the first argument of the coroutine we have. Thus, we will do a default malloc trick - we will allocate longer block for the coroutine frame in which we will store the allocator object itself. This way, we will be able to restore allocator in delete so we don't need to rely on proper `delete` overload.
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To support proper deallocation, it is required that we store allocator somewhere through the whole coroutine lifetime. The issue is that we cannot just override
delete- it is called after thepromise_typedestructor, meaning we cannot store allocator object there. Thus, we will do a default malloc trick - we will allocate longer block for the coroutine frame in which we will store the allocator object itself. This way, we will be able to restore allocator in delete so we don't need to rely on properdeleteoverload. Sadly, compiler does not propagate rvalue allocator no matter the type of the first argument of the coroutine we have, that's why we now need to require allocator to be copy-constructible. A respective recommendation to keep custom implementations lightweight is given in the concept brief.Additionaly renamed
exampletoExampleDefaultTaskImpland added aExampleCustomAllocatorwhich demonstrates how to specify custom allocator for the contract.