cargo-mutants 23.6.0

An exciting release that adds a lot more power to generate viable mutations of functions returning more complex types.

• Generate Box::leak(Box::new(...)) as a mutation of functions returning &mut.

• Add a concept of mutant "genre", which is included in the json listing of mutants. The only genre today is FnValue, in which a function body is replaced by a value. This will in future allow filtering by genre.

• Recurse into return types, so that for example Result<bool> can generate Ok(true) and Ok(false), and Some<T> generates None and every generated value of T. Similarly for Box<T>, and Vec<T>.

• Generate specific values for integers: [0, 1] for unsigned integers, [0, 1, -1] for signed integers; [1] for NonZero unsigned integers and [1, -1] for NonZero signed integers.

• Generate specific values for floats: [0.0, 1.0, -1.0].

• Generate (fixed-length) array values, like [0; 256], [1; 256] using every recursively generated value for the element type.