The feature in OxCaml that more languages should steal (theconsensus.dev)

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Swift has `@_noAllocation`:

@_noAllocation func foo() -> Int { return [1,2,3].randomElement()! } fails with "error: Using type 'Int' can cause metadata allocation or locks"

but

@_noAllocation func foo() -> Int { return 1 + 2 + 3 }

compiles fine.