manishearth/humpty_dumpty

Implicit Drop/move protection for Rust (linear types)

Humpty Dumpty

The goal of this library is to be able to define types that cannot be implicitly dropped except in controlled situations.

A sketch of the design can be found here. The design does not handle branches, though it can be extended to do so. It's also a bit different from what I finally implemented

The idea is, that for a type that is marked #[drop_protection], only functions annotated with #[allowed_on_protected] can use these, and each local must be dropped with a function marked #[allowed_drop] before its scope finishes.

Current status: Is able to track such types and report on their usage. Maintains a list of what has been dropped properly to detect implicit drops.

Some missing (but planned) functionality:

• Cannot yet handle conditional drops, i.e. those in branches.
• Cannot yet handle any bindings other than a let binding
• Allowed functions cannot yet take &/&mut inputs
• Cannot yet mark method calls as allowed

To test, run cargo run --example test, or even better rustc examples/test.rs -L target (after building). The latter is better because it will rebuild every time, and we're only interested in build output.