Add a package definition for 5.8 builds

Author: phausler

Package@swift-5.8.swift

@@ -0,0 +1,62 @@
+// swift-tools-version: 5.8
+
+import PackageDescription
+import CompilerPluginSupport
+
+// Availability Macros
+
+let availabilityMacros: [SwiftSetting] = [
+  .enableExperimentalFeature("AvailabilityMacro=AsyncAlgorithms 1.0:macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0"),
+  .enableExperimentalFeature("AvailabilityMacro=AsyncAlgorithms 1.1:macOS 15.0, iOS 18.0, tvOS 18.0, watchOS 11.0, visionOS 2.0"),
+]
+
+let package = Package(
+  name: "swift-async-algorithms",
+  products: [
+    .library(name: "AsyncAlgorithms", targets: ["AsyncAlgorithms"])
+  ],
+  targets: [
+    .target(
+      name: "AsyncAlgorithms",
+      dependencies: [
+        .product(name: "OrderedCollections", package: "swift-collections"),
+        .product(name: "DequeModule", package: "swift-collections"),
+      ],
+      swiftSettings: availabilityMacros + [
+        .enableExperimentalFeature("StrictConcurrency=complete")
+      ]
+    ),
+    .target(
+      name: "AsyncSequenceValidation",
+      dependencies: ["_CAsyncSequenceValidationSupport", "AsyncAlgorithms"],
+      swiftSettings: availabilityMacros + [
+        .enableExperimentalFeature("StrictConcurrency=complete")
+      ]
+    ),
+    .systemLibrary(name: "_CAsyncSequenceValidationSupport"),
+    .target(
+      name: "AsyncAlgorithms_XCTest",
+      dependencies: ["AsyncAlgorithms", "AsyncSequenceValidation"],
+      swiftSettings: availabilityMacros + [
+        .enableExperimentalFeature("StrictConcurrency=complete")
+      ]
+    ),
+    .testTarget(
+      name: "AsyncAlgorithmsTests",
+      dependencies: ["AsyncAlgorithms", "AsyncSequenceValidation", "AsyncAlgorithms_XCTest"],
+      swiftSettings: availabilityMacros + [
+        .enableExperimentalFeature("StrictConcurrency=complete")
+      ]
+    ),
+  ]
+)
+
+if Context.environment["SWIFTCI_USE_LOCAL_DEPS"] == nil {
+  package.dependencies += [
+    .package(url: "https://github.com/apple/swift-collections.git", from: "1.1.0"),
+  ]
+} else {
+  package.dependencies += [
+    .package(path: "../swift-collections")
+  ]
+}