Miscellaneous fixes for Wasm platform toward SwiftPM integration

Sources/SWBCore/DependencyResolution.swift

@@ -206,7 +206,17 @@ struct SpecializationParameters: Hashable, CustomStringConvertible {
     func imposed(on parameters: BuildParameters, workspaceContext: WorkspaceContext) -> BuildParameters {
         var overrides = parameters.overrides
         if let sdkRoot {
-            overrides["SDKROOT"] = sdkRoot
+            // The sdkCanonicalName from a Platform is not guaranteed to be available
+            let defaultSDKAvailable: Bool
+            do {
+                let foundSDK = try workspaceContext.core.sdkRegistry.lookup(sdkRoot, activeRunDestination: parameters.activeRunDestination)
+                defaultSDKAvailable = foundSDK != nil
+            } catch {
+                defaultSDKAvailable = false
+            }
+            if defaultSDKAvailable {
+                overrides["SDKROOT"] = sdkRoot
+            }
         }
         if let sdkVariant {
             overrides["SDK_VARIANT"] = sdkVariant.name

Sources/SWBCore/SwiftSDK.swift

@@ -52,13 +52,10 @@ public struct SwiftSDK: Sendable {
     /// Target-specific properties for this SDK.
     public let targetTriples: [String: TripleProperties]
 
-    init?(identifier: String, version: String, path: Path, fs: any FSProxy) throws {
+    init?(identifier: String, version: String, metadataPath: Path, fs: any FSProxy) throws {
         self.identifier = identifier
         self.version = version
-        self.path = path
-
-        let metadataPath = path.join("swift-sdk.json")
-        guard fs.exists(metadataPath) else { return nil }
+        self.path = metadataPath.dirname
 
         let metadataData = try Data(fs.read(metadataPath))
         let schema = try JSONDecoder().decode(SchemaVersionInfo.self, from: metadataData)
@@ -70,6 +67,8 @@ public struct SwiftSDK: Sendable {
 
     /// The default location storing Swift SDKs installed by SwiftPM.
     static func defaultSwiftSDKsDirectory(hostOperatingSystem: OperatingSystem) throws -> Path {
+        // NOTE: Keep in sync with SwiftPM's defaultSwiftSDKsDirectory implementation.
+        // https://github.com/swiftlang/swift-package-manager/blob/deac56dc94d85d28f2f2b5c37ec347ae3523a3fe/Sources/Basics/FileSystem/FileSystem%2BExtensions.swift#L492
         let spmURL: URL
         if hostOperatingSystem == .macOS {
             spmURL = try FileManager.default.url(
@@ -79,7 +78,11 @@ public struct SwiftSDK: Sendable {
                 create: false
             ).appendingPathComponent("org.swift.swiftpm")
         } else {
-            spmURL = URL.homeDirectory.appendingPathComponent(".swiftpm")
+            if let configurationDirectory = Environment.current["XDG_CONFIG_HOME"] {
+                spmURL = URL(fileURLWithPath: configurationDirectory, isDirectory: true).appendingPathComponent("swiftpm")
+            } else {
+                spmURL = URL.homeDirectory.appendingPathComponent(".swiftpm")
+            }
         }
         return try spmURL.appendingPathComponent("swift-sdks").filePath
     }
@@ -137,13 +140,20 @@ public struct SwiftSDK: Sendable {
 
         for (identifier, artifact) in info.artifacts {
             for variant in artifact.variants {
-                let sdkPath = artifactBundle.join(variant.path)
-                guard fs.isDirectory(sdkPath) else { continue }
+                // A variant's path may be a directory or a file. If it's a directory, we assume it
+                // contains a swift-sdk.json file. If it's a file, we use it directly as a Swift SDK
+                // metadata file.
+                var sdkPath = artifactBundle.join(variant.path)
+                if sdkPath.fileExtension != "json" && fs.isDirectory(sdkPath) {
+                    sdkPath = sdkPath.join("swift-sdk.json")
+                }
+
+                guard fs.exists(sdkPath) else { continue }
 
                 // FIXME: For now, we only support SDKs that are compatible with any host triple.
                 guard variant.supportedTriples?.isEmpty ?? true else { continue }
 
-                guard let sdk = try SwiftSDK(identifier: identifier, version: artifact.version, path: sdkPath, fs: fs) else { continue }
+                guard let sdk = try SwiftSDK(identifier: identifier, version: artifact.version, metadataPath: sdkPath, fs: fs) else { continue }
                 // Filter out SDKs that don't support any of the target triples.
                 if let targetTriples {
                     guard targetTriples.contains(where: { sdk.targetTriples[$0] != nil }) else { continue }

Sources/SWBWebAssemblyPlatform/Plugin.swift

@@ -106,10 +106,6 @@ struct WebAssemblySDKRegistryExtension: SDKRegistryExtension {
                         "LLVM_TARGET_TRIPLE_OS_VERSION": .plString(os),
                         "SWIFT_LIBRARY_PATH": .plString(swiftResourceDir.join("wasi").str),
                         "SWIFT_RESOURCE_DIR": .plString(swiftResourceDir.str),
-                        // HACK: Ld step does not use swiftc as linker driver but instead uses clang, so we need to add some Swift specific flags
-                        // assuming static linking.
-                        // Tracked in https://github.com/swiftlang/swift-build/issues/3
-                        "OTHER_LDFLAGS": .plArray(["-lc++", "-lc++abi", "-resource-dir", "$(SWIFT_RESOURCE_DIR)/clang", "@$(SWIFT_LIBRARY_PATH)/static-executable-args.lnk"]),
                     ]),
                     "SupportedTargets": .plDict([
                         "webassembly": .plDict([

Sources/SWBWebAssemblyPlatform/Specs/WasmLd.xcspec

@@ -148,6 +148,30 @@
                 Type = Path;
                 Condition = "NO"; // wasm-ld does not support -filelist
             },
+            {
+                Name = "SWIFTC_LINKER_RESOURCE_DIR";
+                Type = Path;
+                DefaultValue = "$(SWIFT_RESOURCE_DIR)";
+                Condition = "$(LINKER_DRIVER) == swiftc";
+                CommandLineArgs = (
+                    "-resource-dir",
+                    "$(value)",
+                    "-Xclang-linker",
+                    "-resource-dir",
+                    "-Xclang-linker",
+                    "$(value)/clang",
+                );
+                IsInputDependency = Yes;
+            },
+            // TODO(yuta): Remove this override entry after https://github.com/swiftlang/swift-driver/pull/2053
+            {
+                Name = SWIFTC_SDKROOT_LINKER_INPUT;
+                Type = Path;
+                DefaultValue = "$(SYSROOT:default=$(SDKROOT))";
+                Condition = "$(LINKER_DRIVER) == swiftc";
+                CommandLineFlag = "-sdk";
+                IsInputDependency = Yes;
+            },
         );
     },
 )