[codex] Drop Swift 6.1/6.2 support and raise MSSV to 6.3 (#762)

* drop swift 6.1

* fix ci matrix

* Detach async JS bridge tasks

* Stabilize identity GC test

* Revert detached async bridge tasks

* Use Swift 6.2.4 in CI

* Use Swift 6.2.3 in CI

* Drop Swift 6.2 from CI

* Document minimum Swift version

* Add MSSV section to README

* Fix async closure test formatting

* Move tracing override to 24.04 matrix entry

Author: kateinoigakukun

.github/workflows/test.yml

@@ -12,18 +12,13 @@ jobs:
     strategy:
       matrix:
         entry:
-          - os: ubuntu-22.04
-            toolchain:
-              download-url: https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-RELEASE/swift-6.1-RELEASE-ubuntu22.04.tar.gz
-            wasi-backend: Node
-            target: "wasm32-unknown-wasi"
-            env: |
-              JAVASCRIPTKIT_DISABLE_TRACING_TRAIT=1
           - os: ubuntu-24.04
             toolchain:
               download-url: https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT-SNAPSHOT-2025-12-01-a/swift-DEVELOPMENT-SNAPSHOT-2025-12-01-a-ubuntu24.04.tar.gz
             wasi-backend: Node
             target: "wasm32-unknown-wasip1"
+            env: |
+              JAVASCRIPTKIT_DISABLE_TRACING_TRAIT=1
           - os: ubuntu-24.04
             toolchain:
               download-url: https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DEVELOPMENT-SNAPSHOT-2026-03-05-a/swift-6.3-DEVELOPMENT-SNAPSHOT-2026-03-05-a-ubuntu24.04.tar.gz
@@ -77,10 +72,6 @@ jobs:
     strategy:
       matrix:
         entry:
-          - image: "swift:6.1.2"
-            swift-syntax-version: "601.0.0"
-          - image: "swift:6.2"
-            swift-syntax-version: "602.0.0"
           - image: "swift:6.3"
             swift-syntax-version: "603.0.0"
     runs-on: ubuntu-latest
@@ -110,7 +101,7 @@ jobs:
       matrix:
         include:
           - os: macos-15
-            xcode: Xcode_16.4
+            xcode: Xcode_26.0.1
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v6
@@ -134,7 +125,7 @@ jobs:
   format:
     runs-on: ubuntu-latest
     container:
-      image: swift:6.1.2
+      image: swift:6.3
     steps:
       - uses: actions/checkout@v6
       - run: ./Utilities/format.swift

Examples/Embedded/README.md

@@ -1,6 +1,6 @@
 # Embedded example
 
-Requires a recent DEVELOPMENT-SNAPSHOT toolchain. (tested with swift-6.1-DEVELOPMENT-SNAPSHOT-2025-02-21-a)
+Requires a recent DEVELOPMENT-SNAPSHOT toolchain.
 
 ```sh
 $ ./build.sh

Package@swift-6.1.swift

@@ -297,7 +297,6 @@ extension Trait where Self == ConditionTrait {
         }
     }
 
-    #if compiler(>=6.1)
     @Test(.requireSwiftSDK)
     func testingWithCoverage() throws {
         let swiftSDKID = try #require(Self.getSwiftSDKID())
@@ -325,7 +324,6 @@ extension Trait where Self == ConditionTrait {
             }
         }
     }
-    #endif
     #endif  // compiler(>=6.3)
 
     @Test(.requireSwiftSDK(triple: "wasm32-unknown-wasip1-threads"))
@@ -379,7 +377,6 @@ extension Trait where Self == ConditionTrait {
         }
     }
 
-    #if compiler(>=6.1)
     // TODO: Remove triple restriction once swift-testing is shipped in p1-threads SDK
     @Test(.requireSwiftSDK(triple: "wasm32-unknown-wasi"))
     func continuationLeakInTest_SwiftTesting() throws {
@@ -391,8 +388,6 @@ extension Trait where Self == ConditionTrait {
             try runSwift(["package", "--disable-sandbox", "--swift-sdk", swiftSDKID, "js", "test"], [:])
         }
     }
-    #endif
-
     @Test(.requireSwiftSDK)
     func playwrightOnPageLoad_XCTest() throws {
         let swiftSDKID = try #require(Self.getSwiftSDKID())
@@ -413,7 +408,6 @@ extension Trait where Self == ConditionTrait {
         }
     }
 
-    #if compiler(>=6.1)
     // TODO: Remove triple restriction once swift-testing is shipped in p1-threads SDK
     @Test(.requireSwiftSDK(triple: "wasm32-unknown-wasi"))
     func playwrightOnPageLoad_SwiftTesting() throws {
@@ -434,5 +428,4 @@ extension Trait where Self == ConditionTrait {
             )
         }
     }
-    #endif
 }

Plugins/PackageToJS/Tests/ExampleTests.swift

@@ -120,6 +120,10 @@ Use the [BridgeJS Playground](https://swiftwasm.org/JavaScriptKit/PlayBridgeJS/)
 
 Check out the [examples](https://github.com/swiftwasm/JavaScriptKit/tree/main/Examples) for more detailed usage patterns.
 
+## Minimum Supported Swift Version (MSSV)
+
+The minimum supported Swift version is 6.3.
+
 ## Contributing
 
 Contributions are welcome! See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to the project.

README.md

@@ -62,7 +62,7 @@ extension JSRemote where T == JSObject {
     ///
     /// - Parameter object: The JavaScript object to reference remotely.
     public init(_ object: JSObject) {
-        #if compiler(>=6.1) && _runtime(_multithreaded)
+        #if _runtime(_multithreaded)
         self.init(sourceObject: object, sourceTid: object.ownerTid)
         #else
         self.init(sourceObject: object, sourceTid: -1)
@@ -92,7 +92,7 @@ extension JSRemote where T == JSObject {
     public func withJSObject<R: Sendable, E: Error>(
         _ body: @Sendable @escaping (JSObject) throws(E) -> R
     ) async throws(E) -> sending R {
-        #if compiler(>=6.1) && _runtime(_multithreaded)
+        #if _runtime(_multithreaded)
         if storage.sourceTid == swjs_get_worker_thread_id_cached() {
             return try body(storage.sourceObject)
         }
@@ -137,13 +137,11 @@ private final class _JSRemoteContext: @unchecked Sendable {
     }
 }
 
-#if compiler(>=6.1)
 @_expose(wasm, "swjs_invoke_remote_jsobject_body")
 @_cdecl("swjs_invoke_remote_jsobject_body")
-#endif
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 func _swjs_invoke_remote_jsobject_body(_ contextPtr: UnsafeRawPointer?) -> Bool {
-    #if compiler(>=6.1) && _runtime(_multithreaded)
+    #if _runtime(_multithreaded)
     guard let contextPtr else { return true }
     let context = Unmanaged<_JSRemoteContext>.fromOpaque(contextPtr).takeRetainedValue()