Tracking issue for potentially useful features in future Rust versions

As of the time of writing, the MSRV for softbuffer is 1.64.0. As far as I can tell there is no MSRV policy, but the informal rule seems to be that the limit is Rust versions released up to seven months ago. This issue keeps track of features that may be useful to softbuffer, but cannot be used yet because we don't have the required Rust version.

• Nightly
  • Fallible allocation could be worked into the error enum to provide a condition for low-memory systems.
  • We implement some parts as what's essentially a try block, but as a closure that is immediately called. Example. It would be nice to replace those cases with a simple try block.
  • We use a Box to wrap SurfaceDispatch in order to keep the type size predictable. However, for low memory systems we could use the allocator_api feature to provide a custom allocator to reduce allocations.

Feel free to add more that I've missed.

Review the MSRV context and the referenced implementations in src/wayland/mod.rs and src/lib.rs. There is no single implementation target or completion condition yet; select a listed Rust feature, confirm its version requirements, and define the resulting change and tests before starting.