6dcdabf37e
This commit refactors the internals of `wiggle` to have fewer raw pointers and more liberally use `&[UnsafeCell<_>]`. The purpose of this refactoring is to more strictly thread through lifetime information throughout the crate to avoid getting it wrong. Additionally storing `UnsafeCell<T>` at rest pushes the unsafety of access to the leaves of modifications where Rust safety guarantees are upheld. Finally this provides what I believe is a safer internal representation of `WasmtimeGuestMemory` since it technically holds onto `&mut [u8]` un-soundly as other `&mut T` pointers are handed out. Additionally generated `GuestTypeTransparent` impls in the `wiggle` macro were removed because they are not safe for shared memories as-is and otherwise aren't needed for WASI today. The trait has been updated to indicate that all bit patterns must be valid in addition to having the same representation on the host as in the guest to accomodate this.
wiggle-generate
This is a library crate that implements all of the component parts of
the wiggle proc-macro crate.
Code lives in a separate non-proc-macro crate so that it can be reused in
other settings, e.g. the lucet-wiggle crate.
Code generated by this crate should not have any references to a particular WebAssembly runtime or engine. It should instead expose traits that may be implemented by an engine. Today, it is consumed by both Lucet and Wasmtime.