Pass toolsets through to preparation for the SwiftPM build server

Also adds some logging to the synchronize request so that it's obvious
when background indexing is being skipped.

Fixes #2373
Resolves rdar://165519940

Author: bnbarham

Sources/BuildServerIntegration/SwiftPMBuildServer.swift

@@ -126,6 +126,10 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
   private let pluginConfiguration: PluginConfiguration
   private let traitConfiguration: TraitConfiguration
 
+  /// Paths to any toolsets provided in `SourceKitLSPOptions`, with any relative paths resolved based on the project
+  /// root.
+  private let toolsets: [AbsolutePath]
+
   /// A `ObservabilitySystem` from `SwiftPM` that logs.
   private let observabilitySystem: ObservabilitySystem
 
@@ -212,6 +216,11 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
     }
 
     let absProjectRoot = try AbsolutePath(validating: projectRoot.filePath)
+    self.toolsets =
+      try options.swiftPMOrDefault.toolsets?.map {
+        try AbsolutePath(validating: $0, relativeTo: absProjectRoot)
+      } ?? []
+
     let hostSDK = try SwiftSDK.hostSwiftSDK(AbsolutePath(validating: destinationToolchainBinDir.filePath))
     let hostSwiftPMToolchain = try UserToolchain(swiftSDK: hostSDK)
 
@@ -230,9 +239,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
     let destinationSDK = try SwiftSDK.deriveTargetSwiftSDK(
       hostSwiftSDK: hostSDK,
       hostTriple: hostSwiftPMToolchain.targetTriple,
-      customToolsets: options.swiftPMOrDefault.toolsets?.map {
-        try AbsolutePath(validating: $0, relativeTo: absProjectRoot)
-      } ?? [],
+      customToolsets: toolsets,
       customCompileTriple: triple,
       swiftSDKSelector: options.swiftPMOrDefault.swiftSDK,
       store: SwiftSDKBundleStore(
@@ -753,6 +760,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
     if let traits = options.swiftPMOrDefault.traits {
       arguments += ["--traits", traits.joined(separator: ",")]
     }
+    arguments += toolsets.flatMap { ["--toolset", $0.pathString] }
     arguments += options.swiftPMOrDefault.cCompilerFlags?.flatMap { ["-Xcc", $0] } ?? []
     arguments += options.swiftPMOrDefault.cxxCompilerFlags?.flatMap { ["-Xcxx", $0] } ?? []
     arguments += options.swiftPMOrDefault.swiftCompilerFlags?.flatMap { ["-Xswiftc", $0] } ?? []

Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift

@@ -632,7 +632,7 @@ package struct UpdateIndexStoreTaskDescription: IndexTaskDescription {
       // Indexing will frequently fail if the source code is in an invalid state. Thus, log the failure at a low level.
       logger.debug(
         """
-        Updating index store for terminated with non-zero exit code \(code) for \(indexFiles)
+        Updating index store terminated with non-zero exit code \(code) for \(indexFiles)
         Stderr:
         \(stderr)
         Stdout:
@@ -645,7 +645,7 @@ package struct UpdateIndexStoreTaskDescription: IndexTaskDescription {
         // The indexing job finished with a signal. Could be because the compiler crashed.
         // Ignore signal exit codes if this task has been cancelled because the compiler exits with SIGINT if it gets
         // interrupted.
-        logger.error("Updating index store for signaled \(signal) for \(indexFiles)")
+        logger.error("Updating index store signaled \(signal) for \(indexFiles)")
         BuildSettingsLogger.log(level: .error, settings: buildSettings, for: indexFiles)
       }
     case .abnormal(let exception):

Sources/SourceKitLSP/Workspace.swift

@@ -524,8 +524,14 @@ package final class Workspace: Sendable, BuildServerManagerDelegate {
       await buildServerManager.scheduleRecomputeCopyFileMap().value
     }
     if request.index ?? false {
-      await semanticIndexManager?.waitForUpToDateIndex()
-      await uncheckedIndex?.pollForUnitChangesAndWait()
+      if let semanticIndexManager = await semanticIndexManager {
+        await semanticIndexManager.waitForUpToDateIndex()
+      } else {
+        logger.debug("Skipping wait for background index in synchronize as it's disabled")
+
+        // Might have index while building, so still need to poll for any changes
+        await uncheckedIndex?.pollForUnitChangesAndWait()
+      }
     }
   }
 }

Tests/BuildServerIntegrationTests/SwiftPMBuildServerTests.swift

@@ -1111,6 +1111,74 @@ struct SwiftPMBuildServerTests {
       #expect(compilerArgs.contains(try manifestURL.filePath))
     }
   }
+
+  @Test(
+    .enabled(if: Platform.current != .windows, "Toolsets are not working on Windows, see swift-package-manager#9438.")
+  )
+  func testToolsets() async throws {
+    let project = try await SwiftPMTestProject(
+      files: [
+        "Foo/foo.swift": """
+        import Bar
+
+        func foo() {
+          bar()
+        }
+        """,
+        "Bar/bar.swift": """
+        #if BAR
+        public func bar() {}
+        #endif
+        """,
+        "/toolset.json": """
+        {
+          "schemaVersion": "1.0",
+          "swiftCompiler": {
+            "extraCLIOptions": [
+              "-DBAR"
+            ]
+          }
+        }
+        """,
+        "/.sourcekit-lsp/config.json": """
+        {
+          "swiftPM": {
+            "toolsets": ["toolset.json"]
+          }
+        }
+        """,
+      ],
+      manifest: """
+        let package = Package(
+          name: "MyLibrary",
+          targets: [
+            .target(name: "Foo", dependencies: ["Bar"]),
+            .target(name: "Bar"),
+          ]
+        )
+        """,
+      options: .testDefault(experimentalFeatures: [.sourceKitOptionsRequest]),
+      enableBackgroundIndexing: true,
+    )
+
+    let (uri, _) = try project.openDocument("foo.swift")
+
+    let options = try await project.testClient.send(
+      SourceKitOptionsRequest(
+        textDocument: TextDocumentIdentifier(uri),
+        prepareTarget: false,
+        allowFallbackSettings: false
+      )
+    )
+    #expect(options.compilerArguments.contains("-DBAR"))
+
+    let diagnostics = try #require(
+      await project.testClient.send(
+        DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri))
+      ).fullReport?.items
+    )
+    #expect(diagnostics.isEmpty)
+  }
 }
 
 private func expectArgumentsDoNotContain(