Constify `Box<T, A>` methods by woppopo · Pull Request #91884 · rust-lang/...

Please implement these.

This is a type for testing, so I omitted some implementations. Should I still implement these?

It is fine to leave them unimplemented for now, but I think they should be implemented before merging. You may be able to copy the default implementation of these methods.

I have implemented these, but the methods aren't called in the testcases, we can't check if they are implemented correctly. Also we may need to implement const_deallocate to the compiler.

Const deallocation is simply leaking the thing. The mir interpreter cleans up all dangling allocations

Also we may need to implement const_deallocate to the compiler.

I just saw you open a PR to add this, let me emphasize: This PR cannot contain any use of that intrinsic. The nature of ConstAlloc/CtfeAlloc is to leak when dropping, which means you can't realistically use it in this test allocator impl.

The nature of ConstAlloc/CtfeAlloc is to leak when dropping

And why is that?
I don't think this should be the case, at least for allocations that are created and then deallocated within the same const-evalaution. (Of course, at runtime deallocation is a NOP, since static memory cannot be deallocated and it is shared among all the copies of the constant anyway.)

Well, looks like const_eval_select can resolve this problem faily easily.

I don't think that is enough -- if one const works on something that was allocated in a different const, deallocation should still be a NOP.