[Pitch] Conditional compilation for the deployment target

Would it make sense to support conditional compilation based on the minimum deployment target? #if deploymentTarget(>=27.0) // Implementation for projects targeting OS 27+ #else // Backwards-compatible implementation #endif if #available cannot replace this when conditionally compiling declarations, conformances, imports, or type aliases. Which duplicates information the compiler already has and must be kept in sync with the actual deployment target. The compiler already gets this version fro...