Auto merge of #80824 - cuviper:heap-clones, r=kennytm

Try to avoid locals when cloning into Box/Rc/Arc

For generic `T: Clone`, we can allocate an uninitialized box beforehand,
which gives the optimizer a chance to create the clone directly in the
heap. For `T: Copy`, we can go further and do a simple memory copy,
regardless of optimization level.

The same applies to `Rc`/`Arc::make_mut` when they must clone the data.

0 files changed, 0 insertions, 0 deletions