0.49.1

Fix soundness bug introduced

We previously switched our underlying type system model. In the process, a soundness hole was introduced where users could assign values to variables with an ephemeral capability. This could lead to "very bad things".

The hole was introduced in May of 2021 by PR #3643. We've closed the hole so that code such as the following will again be rejected by the compiler.

let map: Map[String, Array[String]] trn^ = recover trn Map[String, Array[String]] end

[0.49.1] - 2022-03-13

Fixed

• Ban unstable variables (PR #4018)