Swift 6 language mode support needed

[hassila]

let 'benchmarks' is not concurrency-safe because non-'Sendable' type '() -> ()' may have shared mutable state

[t089]

What is the workaround here?

Use explicit type:

let benchmarks : @Sendable () -> Benchmark? = {

[toffaletti]

If you have many Benchmark:

let benchmarks : @Sendable () -> Void = {