Swift’s Upcoming Feature Flags
The idea of being able to adopt upcoming changes sooner rather than later is a good one. However, adding an ever-increasing number of separate compiler flags for each upcoming feature does not scale well.
To address this, Swift evolution proposal SE-0362, implemented in Swift 5.8, details a generalized mechanism for enabling upcoming features.
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SE-0362 also introduces a new
hasFeature()compilation condition that checks whether a feature is enabled. This allows you to write code that uses a feature if present or uses alternate code if not present.
Previously:
