Support using SourceKit-LSP for projects that are cross-compiled

We previously always assumed that the project was being built for the host.

Fixes #1475
rdar://129662080

Author: ahoppen

Documentation/Configuration File.md

@@ -13,12 +13,15 @@ The structure of the file is currently not guaranteed to be stable. Options may
 `config.json` is a JSON file with the following structure. All keys are optional and unknown keys are ignored.
 
 - `swiftPM`: Dictionary with the following keys, defining options for SwiftPM workspaces
-  - `configuration: "debug"|"release"`: The configuration to build the project for during background indexing and the configuration whose build folder should be used for Swift modules if background indexing is disabled
-  - `scratchPath: string`: Build artifacts directory path. If nil, the build system may choose a default value
-  - `cCompilerFlags: string[]`: Extra arguments passed to the compiler for C files
-  - `cxxCompilerFlags: string[]`: Extra arguments passed to the compiler for C++ files
-  - `swiftCompilerFlags: string[]`: Extra arguments passed to the compiler for Swift files
-  - `linkerFlags: string[]`: Extra arguments passed to the linker
+  - `configuration: "debug"|"release"`: The configuration to build the project for during background indexing and the configuration whose build folder should be used for Swift modules if background indexing is disabled. Equivalent to SwiftPM's `--configuration` option.
+  - `scratchPath: string`: Build artifacts directory path. If nil, the build system may choose a default value. Equivalent to SwiftPM's `--scratch-path` option.
+  - `swiftSDKsDirectory: string`: Equivalent to SwiftPM's `--swift-sdks-path` option
+  - `swiftSDK: string`: Equivalent to SwiftPM's `--swift-sdk` option
+  - `triple: string`: Equivalent to SwiftPM's `--triple` option
+  - `cCompilerFlags: string[]`: Extra arguments passed to the compiler for C files. Equivalent to SwiftPM's `-Xcc` option.
+  - `cxxCompilerFlags: string[]`: Extra arguments passed to the compiler for C++ files. Equivalent to SwiftPM's `-Xcxx` option.
+  - `swiftCompilerFlags: string[]`: Extra arguments passed to the compiler for Swift files. Equivalent to SwiftPM's `-Xswiftc` option.
+  - `linkerFlags: string[]`: Extra arguments passed to the linker. Equivalent to SwiftPM's `-Xlinker` option.
 - `compilationDatabase`: Dictionary with the following keys, defining options for workspaces with a compilation database
   - `searchPaths: string[]`: Additional paths to search for a compilation database, relative to a workspace root.
 - `fallbackBuildSystem`: Dictionary with the following keys, defining options for files that aren't managed by any build system

Sources/SKCore/SourceKitLSPOptions.swift

@@ -23,26 +23,52 @@ import struct TSCBasic.AbsolutePath
 public struct SourceKitLSPOptions: Sendable, Codable {
   public struct SwiftPMOptions: Sendable, Codable {
     /// Build configuration (debug|release).
+    ///
+    /// Equivalent to SwiftPM's `--configuration` option.
     public var configuration: BuildConfiguration?
 
     /// Build artifacts directory path. If nil, the build system may choose a default value.
+    ///
+    /// Equivalent to SwiftPM's `--scratch-path` option.
     public var scratchPath: String?
 
+    /// Equivalent to SwiftPM's `--swift-sdks-path` option
+    public var swiftSDKsDirectory: String?
+
+    /// Equivalent to SwiftPM's `--swift-sdk` option
+    public var swiftSDK: String?
+
+    /// Equivalent to SwiftPM's `--triple` option
+    public var triple: String?
+
+    /// Equivalent to SwiftPM's `-Xcc` option
     public var cCompilerFlags: [String]?
+
+    /// Equivalent to SwiftPM's `-Xcxx` option
     public var cxxCompilerFlags: [String]?
+
+    /// Equivalent to SwiftPM's `-Xswiftc` option
     public var swiftCompilerFlags: [String]?
+
+    /// Equivalent to SwiftPM's `-Xlinker` option
     public var linkerFlags: [String]?
 
     public init(
       configuration: BuildConfiguration? = nil,
       scratchPath: String? = nil,
+      swiftSDKsDirectory: String? = nil,
+      swiftSDK: String? = nil,
+      triple: String? = nil,
       cCompilerFlags: [String]? = nil,
       cxxCompilerFlags: [String]? = nil,
       swiftCompilerFlags: [String]? = nil,
       linkerFlags: [String]? = nil
     ) {
       self.configuration = configuration
       self.scratchPath = scratchPath
+      self.swiftSDKsDirectory = swiftSDKsDirectory
+      self.swiftSDK = swiftSDK
+      self.triple = triple
       self.cCompilerFlags = cCompilerFlags
       self.cxxCompilerFlags = cxxCompilerFlags
       self.swiftCompilerFlags = swiftCompilerFlags
@@ -53,6 +79,9 @@ public struct SourceKitLSPOptions: Sendable, Codable {
       return SwiftPMOptions(
         configuration: override?.configuration ?? base.configuration,
         scratchPath: override?.scratchPath ?? base.scratchPath,
+        swiftSDKsDirectory: override?.swiftSDKsDirectory ?? base.swiftSDKsDirectory,
+        swiftSDK: override?.swiftSDK ?? base.swiftSDK,
+        triple: override?.triple ?? base.triple,
         cCompilerFlags: override?.cCompilerFlags ?? base.cCompilerFlags,
         cxxCompilerFlags: override?.cxxCompilerFlags ?? base.cxxCompilerFlags,
         swiftCompilerFlags: override?.swiftCompilerFlags ?? base.swiftCompilerFlags,

Sources/SKSwiftPMWorkspace/SwiftPMBuildSystem.swift

@@ -222,8 +222,29 @@ public actor SwiftPMBuildSystem {
       throw Error.cannotDetermineHostToolchain
     }
 
-    let swiftSDK = try SwiftSDK.hostSwiftSDK(AbsolutePath(destinationToolchainBinDir))
-    let swiftPMToolchain = try UserToolchain(swiftSDK: swiftSDK)
+    let hostSDK = try SwiftSDK.hostSwiftSDK(AbsolutePath(destinationToolchainBinDir))
+    let hostSwiftPMToolchain = try UserToolchain(swiftSDK: hostSDK)
+
+    var destinationSDK: SwiftSDK
+    if let swiftSDK = options.swiftSDK {
+      let bundleStore = try SwiftSDKBundleStore(
+        swiftSDKsDirectory: fileSystem.getSharedSwiftSDKsDirectory(
+          explicitDirectory: options.swiftSDKsDirectory.map { try AbsolutePath(validating: $0) }
+        ),
+        fileSystem: fileSystem,
+        observabilityScope: observabilitySystem.topScope,
+        outputHandler: { _ in }
+      )
+      destinationSDK = try bundleStore.selectBundle(matching: swiftSDK, hostTriple: hostSwiftPMToolchain.targetTriple)
+    } else {
+      destinationSDK = hostSDK
+    }
+
+    if let triple = options.triple {
+      destinationSDK = hostSDK
+      destinationSDK.targetTriple = try Triple(triple)
+    }
+    let destinationSwiftPMToolchain = try UserToolchain(swiftSDK: destinationSDK)
 
     var location = try Workspace.Location(
       forRootPackage: AbsolutePath(packageRoot),
@@ -244,7 +265,7 @@ public actor SwiftPMBuildSystem {
       fileSystem: fileSystem,
       location: location,
       configuration: configuration,
-      customHostToolchain: swiftPMToolchain
+      customHostToolchain: hostSwiftPMToolchain
     )
 
     let buildConfiguration: PackageModel.BuildConfiguration
@@ -265,20 +286,21 @@ public actor SwiftPMBuildSystem {
     self.toolsBuildParameters = try BuildParameters(
       destination: .host,
       dataPath: location.scratchDirectory.appending(
-        component: swiftPMToolchain.targetTriple.platformBuildPathComponent
+        component: hostSwiftPMToolchain.targetTriple.platformBuildPathComponent
       ),
       configuration: buildConfiguration,
-      toolchain: swiftPMToolchain,
+      toolchain: hostSwiftPMToolchain,
       flags: buildFlags
     )
 
     self.destinationBuildParameters = try BuildParameters(
       destination: .target,
       dataPath: location.scratchDirectory.appending(
-        component: swiftPMToolchain.targetTriple.platformBuildPathComponent
+        component: destinationSwiftPMToolchain.targetTriple.platformBuildPathComponent
       ),
       configuration: buildConfiguration,
-      toolchain: swiftPMToolchain,
+      toolchain: destinationSwiftPMToolchain,
+      triple: destinationSDK.targetTriple,
       flags: buildFlags
     )
 

Tests/SourceKitLSPTests/SwiftPMIntegration.swift

@@ -241,4 +241,53 @@ final class SwiftPMIntegrationTests: XCTestCase {
       ]
     )
   }
+
+  func testWasm() async throws {
+    let project = try await SwiftPMTestProject(
+      files: [
+        "/.sourcekit-lsp/config.json": """
+        {
+          "swiftPM": {
+            "triple": "wasm32-unknown-none-wasm"
+          }
+        }
+        """,
+        "Test.swift": """
+        #if arch(wasm32)
+        let _: UnsafeRawPointer = 1
+        #endif
+        """,
+      ],
+      manifest: """
+        let package = Package(
+          name: "WasmTest",
+          targets: [
+            .executableTarget(
+              name: "wasmTest",
+              cSettings: [.unsafeFlags(["-fdeclspec"])],
+              swiftSettings: [
+                .enableExperimentalFeature("Embedded"),
+                .interoperabilityMode(.Cxx),
+                .unsafeFlags(["-wmo", "-disable-cmo", "-Xfrontend", "-gnone"]),
+              ],
+              linkerSettings: [.unsafeFlags(["-Xclang-linker", "-nostdlib", "-Xlinker", "--no-entry"])]
+            )
+          ]
+        )
+        """
+    )
+
+    let (uri, _) = try project.openDocument("Test.swift")
+    let diagnostics = try await project.testClient.send(
+      DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri))
+    )
+    guard case .full(let diagnostics) = diagnostics else {
+      XCTFail("Expected full diagnostics report")
+      return
+    }
+    XCTAssertEqual(
+      diagnostics.items.map(\.message),
+      ["Cannot convert value of type 'Int' to specified type 'UnsafeRawPointer'"]
+    )
+  }
 }