Update -swift-version to default to 6 for swift-tools-version 6

We missed updating this when adding 6.0.

Author: bnbarham

Sources/PackageModel/ToolsVersion.swift

@@ -182,10 +182,11 @@ public struct ToolsVersion: Equatable, Hashable, Codable, Sendable {
 
             // Otherwise, use 4.2
             return .v4_2
-
-        default:
-            // Anything above 4 major version uses version 5.
+        case 5:
             return .v5
+        default:
+            // Anything above 5 major version uses version 6.
+            return .v6
         }
     }
 }

Tests/BuildTests/BuildPlanTests.swift

@@ -6260,4 +6260,51 @@ final class BuildPlanTests: XCTestCase {
         let dylibs = Array(buildProduct.dylibs.map({$0.product.name})).sorted()
         XCTAssertEqual(dylibs, ["BarLogging", "FooLogging"])
     }
+
+    func testDefaultVersions() throws {
+        let fs = InMemoryFileSystem(emptyFiles:
+            "/Pkg/Sources/foo/foo.swift"
+        )
+
+        let expectedVersions = [
+          ToolsVersion.v4: "4",
+          ToolsVersion.v4_2: "4.2",
+          ToolsVersion.v5: "5",
+          ToolsVersion.v6_0: "6",
+          ToolsVersion.vNext: "6"
+        ]
+        for (toolsVersion, expectedVersionString) in expectedVersions {
+            let observability = ObservabilitySystem.makeForTesting()
+            let graph = try loadModulesGraph(
+              fileSystem: fs,
+              manifests: [
+                Manifest.createRootManifest(
+                  displayName: "Pkg",
+                  path: "/Pkg",
+                  toolsVersion: toolsVersion,
+                  targets: [
+                    TargetDescription(
+                      name: "foo"
+                    ),
+                  ]
+                ),
+              ],
+              observabilityScope: observability.topScope
+            )
+
+            let result = try BuildPlanResult(plan: BuildPlan(
+              buildParameters: mockBuildParameters(),
+              graph: graph,
+              fileSystem: fs,
+              observabilityScope: observability.topScope
+            ))
+
+            XCTAssertMatch(
+              try result.target(for: "foo").swiftTarget().compileArguments(),
+              [
+                "-swift-version", .equal(expectedVersionString)
+              ]
+            )
+        }
+    }
 }

Tests/PackageLoadingTests/PackageBuilderTests.swift

@@ -3023,7 +3023,7 @@ final class PackageBuilderTests: XCTestCase {
         }
     }
 
-    func testSwiftLanguageVesionPerTarget() throws {
+    func testSwiftLanguageVersionPerTarget() throws {
         let fs = InMemoryFileSystem(emptyFiles:
             "/Sources/foo/foo.swift",
             "/Sources/bar/bar.swift"

Tests/PackageModelTests/ToolsVersionTests.swift

@@ -91,8 +91,12 @@ class ToolsVersionTests: XCTestCase {
             XCTAssertEqual(ToolsVersion(string: version)?.swiftLanguageVersion.description, "4.2")
         }
 
-        for version in ["5.0.0", "5.1.9", "6.0.0", "7.0.0"] {
+        for version in ["5.0.0", "5.1.9"] {
             XCTAssertEqual(ToolsVersion(string: version)?.swiftLanguageVersion.description, "5")
         }
+
+        for version in ["6.0.0", "7.0.0"] {
+            XCTAssertEqual(ToolsVersion(string: version)?.swiftLanguageVersion.description, "6")
+        }
     }
 }