std.allocator issues

[Steven Schveighoffer via Digitalmars-d]

I'm trying to use the std.experimental.allocator API more in my new io 
library, and I'm having a few stumbling points:

1. GCAllocator only allocates void, which is marked as containing 
pointers. This is no good for a stream buffer, and can severely harm 
performance.

2. GCAllocator provides a free function. There's no way for me to tell 
generically that it's OK *not* to free allocations, though. I understand 
we should provide a hook if there exists a way to do so, but there needs 
to be a way to free this. I'd prefer not to free data if it's not 
strictly necessary.

3. GCAllocator needs a mechanism to specify type info for allocations so 
the dtors are properly run in the GC. While not critical for my 
purposes, this is going to be very important, and should be figured out 
before merged into mainline Phobos.

4. Various functions in std.allocator take a ref void[]. This is no 
good. I don't want to store a void[] in my type, because that's not very 
useful, but if I want to reallocate, or expand, then I need to do a 
dance where I copy the array to a void[], do the reallocation, and then 
copy it back (if successful). This fully defeats the point of having a 
ref in the first place. I understand there are wrappers that do this for 
reallocating, but I want to use the other tools as well (expand in 
particular). But principally, to have an API that is mostly unusable 
seems unnecessary.

I really do like the API, and it's fitting in quite nicely! I can work 
around all these at the moment, but I'd love to see these improvements 
in place before making official phobos.

-Steve