RISCfuture · RISCfuture · Jun 27, 2026 · Jun 27, 2026 · Jun 27, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,22 @@
 # Change Log
 
+## [3.1.0] - 2026-06-26
+
+### Changed
+
+- Adopted Swift's Approachable Concurrency upcoming-feature flags
+  (`NonisolatedNonsendingByDefault` and `InferIsolatedConformances`),
+  aligning the package's async execution semantics with modern Swift 6
+  defaults. No public API signatures changed: the async `from(string:)`
+  parsers and the `from(xml:)` `AsyncStream` producers behave the same
+  from a caller's perspective.
+- Dropped the now-redundant `@preconcurrency` qualifier from
+  `import RegexBuilder` across all parser files. Sendability of the
+  cached, actor-confined compiled regexes is still provided by the
+  package's `Regex: @retroactive @unchecked Sendable` conformance, which
+  is retained until the standard library conforms `Regex` to `Sendable`
+  itself.
+
 ## [3.0.1] - 2026-05-14
 
 ### Changed

diff --git a/Package.swift b/Package.swift
@@ -2,6 +2,11 @@
 
 import PackageDescription
 
+let approachableConcurrency: [SwiftSetting] = [
+  .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
+  .enableUpcomingFeature("InferIsolatedConformances")
+]
+
 let package = Package(
   name: "SwiftMETAR",
   defaultLocalization: "en",
@@ -35,42 +40,48 @@ let package = Package(
     .target(
       name: "SwiftMETAR",
       dependencies: [.product(name: "NumberKit", package: "swift-numberkit")],
-      resources: [.process("Resources")]
+      resources: [.process("Resources")],
+      swiftSettings: approachableConcurrency
     ),
     .target(
       name: "METARFormatting",
       dependencies: [
         "SwiftMETAR",
         .product(name: "BuildableMacro", package: "BuildableMacro")
       ],
-      resources: [.process("Resources")]
+      resources: [.process("Resources")],
+      swiftSettings: approachableConcurrency
     ),
     .testTarget(
       name: "SwiftMETARTests",
-      dependencies: ["SwiftMETAR", "Quick", "Nimble"]
+      dependencies: ["SwiftMETAR", "Quick", "Nimble"],
+      swiftSettings: approachableConcurrency
     ),
     .executableTarget(
       name: "DecodeMETAR",
       dependencies: [
         "SwiftMETAR",
         "METARFormatting",
         .product(name: "ArgumentParser", package: "swift-argument-parser")
-      ]
+      ],
+      swiftSettings: approachableConcurrency
     ),
     .executableTarget(
       name: "DecodeTAF",
       dependencies: [
         "SwiftMETAR",
         "METARFormatting",
         .product(name: "ArgumentParser", package: "swift-argument-parser")
-      ]
+      ],
+      swiftSettings: approachableConcurrency
     ),
     .executableTarget(
       name: "DecodeWindsAloft",
       dependencies: [
         "SwiftMETAR",
         .product(name: "ArgumentParser", package: "swift-argument-parser")
-      ]
+      ],
+      swiftSettings: approachableConcurrency
     )
   ],
   swiftLanguageModes: [.v5, .v6]

diff --git a/Sources/SwiftMETAR/Common/Parsers/ConditionsParser.swift b/Sources/SwiftMETAR/Common/Parsers/ConditionsParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class ConditionsParser {
   private let coverageRef = Reference<Coverage>()

diff --git a/Sources/SwiftMETAR/Common/Parsers/DateParser.swift b/Sources/SwiftMETAR/Common/Parsers/DateParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class DayHourMinuteParser {
   private let dateRef = Reference<(UInt8, UInt8, UInt8)>()

diff --git a/Sources/SwiftMETAR/Common/Parsers/NumericParsers.swift b/Sources/SwiftMETAR/Common/Parsers/NumericParsers.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class FractionParser {
   let ref = Reference<Substring>()

diff --git a/Sources/SwiftMETAR/Common/Parsers/VisibilityParser.swift b/Sources/SwiftMETAR/Common/Parsers/VisibilityParser.swift
@@ -1,6 +1,6 @@
 import Foundation
 import NumberKit
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class VisibilityParser {
   private let integerParser = IntegerDistanceParser()

diff --git a/Sources/SwiftMETAR/Common/Parsers/WeatherParser.swift b/Sources/SwiftMETAR/Common/Parsers/WeatherParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class WeatherParser {
   private let intensityRef = Reference<Weather.Intensity>()

diff --git a/Sources/SwiftMETAR/Common/Parsers/WindParser.swift b/Sources/SwiftMETAR/Common/Parsers/WindParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class WindParser {
   let directionRef = Reference<DirectionString>()

diff --git a/Sources/SwiftMETAR/Common/Parsers/WindshearParser.swift b/Sources/SwiftMETAR/Common/Parsers/WindshearParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class WindshearParser {
   private let heightRef = Reference<UInt16>()

diff --git a/Sources/SwiftMETAR/METAR/Parsers/AltimeterParser.swift b/Sources/SwiftMETAR/METAR/Parsers/AltimeterParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class AltimeterParser {
   private let unitRef = Reference<Substring>()

diff --git a/Sources/SwiftMETAR/METAR/Parsers/METARTemperatureParser.swift b/Sources/SwiftMETAR/METAR/Parsers/METARTemperatureParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class METARTemperatureParser {
   private let tempParser = AlphaSignedIntegerParser(width: 2)

diff --git a/Sources/SwiftMETAR/METAR/Parsers/RVRParser.swift b/Sources/SwiftMETAR/METAR/Parsers/RVRParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class RVRParser {
   private let runwayRef = Reference<Substring>()

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/RemarkDirectionParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/RemarkDirectionParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 class RemarkDirectionParser {
   private static let directionFromString: [String: Remark.Direction] = [

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/RemarkParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/RemarkParser.swift
@@ -1,6 +1,6 @@
 import Foundation
 import NumberKit
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 protocol RemarkParser {
   var urgency: Remark.Urgency { get }

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/AircraftMishapParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/AircraftMishapParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class AircraftMishapParser: RemarkParser {
   private static let rx = Regex {

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/CloudTypesParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/CloudTypesParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class CloudTypesParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/CorrectionParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/CorrectionParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class CorrectionParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/DailyPrecipitationAmountParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/DailyPrecipitationAmountParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class DailyPrecipitationAmountParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/DailyTemperatureExtremeParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/DailyTemperatureExtremeParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class DailyTemperatureExtremeParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/HailstoneSizeParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/HailstoneSizeParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class HailstoneSizeParser: RemarkParser {
   var urgency = Remark.Urgency.urgent

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/HourlyPrecipitationAmountParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/HourlyPrecipitationAmountParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class HourlyPrecipitationAmountParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/LastParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/LastParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class LastParser: RemarkParser {
   private static let rx = Regex {

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/LightningParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/LightningParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class LightningParser: RemarkParser {
   var urgency = Remark.Urgency.urgent

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/MaintenanceParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/MaintenanceParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class MaintenanceParser: RemarkParser {
   private static let rx = Regex {

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/NOSIGParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/NOSIGParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class NOSIGParser: RemarkParser {
   private static let rx = Regex {

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/NavalForecasterParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/NavalForecasterParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class NavalForecasterParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/NextParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/NextParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class NextParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/NoAmendmentsAfterParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/NoAmendmentsAfterParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class NoAmendmentsAfterParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/NoSPECIParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/NoSPECIParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class NoSPECIParser: RemarkParser {
   private static let rx = Regex {

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/ObscurationParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/ObscurationParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class ObscurationParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservationTypeParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservationTypeParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class ObservationTypeParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservedPrecipitationParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservedPrecipitationParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class ObservedPrecipitationParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservedVisibilityParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/ObservedVisibilityParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class ObservedVisibilityParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/PeakWindsParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/PeakWindsParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class PeakWindsParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/PeriodicIceAccretionAmountParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/PeriodicIceAccretionAmountParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class PeriodicIceAccretionAmountParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/PeriodicPrecipitationAmountParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/PeriodicPrecipitationAmountParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class PeriodicPrecipitationAmountParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/PrecipitationBeginEndParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/PrecipitationBeginEndParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class PrecipitationBeginEndParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/PressureTendencyParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/PressureTendencyParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class PressureTendencyParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/RapidPressureChangeParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/RapidPressureChangeParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class RapidPressureChangeParser: RemarkParser {
   var urgency = Remark.Urgency.caution

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/RapidSnowIncreaseParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/RapidSnowIncreaseParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class RapidSnowIncreaseParser: RemarkParser {
   var urgency = Remark.Urgency.caution

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/RelativeHumidityParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/RelativeHumidityParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class RelativeHumidityParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/RunwayCeilingParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/RunwayCeilingParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class RunwayCeilingParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/RunwayVisibilityParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/RunwayVisibilityParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class RunwayVisibilityParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/SeaLevelPressureParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/SeaLevelPressureParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class SeaLevelPressureParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/SectorVisibilityParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/SectorVisibilityParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class SectorVisibilityParser: RemarkParser {
   var urgency = Remark.Urgency.routine

diff --git a/Sources/SwiftMETAR/Remarks/Parsers/Types/SensorStatusParser.swift b/Sources/SwiftMETAR/Remarks/Parsers/Types/SensorStatusParser.swift
@@ -1,5 +1,5 @@
 import Foundation
-@preconcurrency import RegexBuilder
+import RegexBuilder
 
 final class SensorStatusParser: RemarkParser {
   var urgency = Remark.Urgency.caution