Adopt Swift 6 language mode

- Update swift-tools-version to 6.0
- Remove feature flags enabled in Swift 6 language mode
- Annotate global flag as nonisolated(unsafe)
- Resolves #29

Author: dempseyatgithub

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 5.9
+// swift-tools-version: 6.0
 
 // This source file is part of the Swift.org open source project
 //
@@ -12,12 +12,7 @@ import PackageDescription
 
 // Settings to use for all targets
 let swiftSettings: [SwiftSetting] = [
-    .enableUpcomingFeature("BareSlashRegexLiterals"),
     .enableUpcomingFeature("ExistentialAny"),
-    .enableUpcomingFeature("ForwardTrailingClosures"),
-    .enableUpcomingFeature("ConciseMagicFile"),
-    .enableUpcomingFeature("ImportObjcForwardDeclarations"),
-    .enableUpcomingFeature("DisableOutwardActorInference"),
 ]
 
 let package = Package(

Sources/EvolutionMetadataExtraction/CommandLineSupport.swift

@@ -10,8 +10,7 @@
 import Foundation
 import ArgumentParser
 
-// Will be nonisolated(unsafe) in Swift 5.10 and later
-private var VERBOSE_ENABLED: Bool = false // Set once in `validate(verbose:)`, read once for `verboseEnabled`.
+nonisolated(unsafe) private var VERBOSE_ENABLED: Bool = false // Set once in `validate(verbose:)`, read once for `verboseEnabled`.
 func verbosePrint(_ items: Any..., additionalCondition: Bool = true, separator: String = " ", terminator: String = "\n\n") {
     if verboseEnabled && additionalCondition { print(items, separator: separator, terminator: terminator) }
 }