If the compiler arguments only contain -o, add the output path as -index-unit-output-path to the adjusted options

Otherwise, we would strip away the `-o`, leaving the command line without any output path option and thus not able to generate a unit file (which requires an output path).

Author: ahoppen

Sources/BuildSystemIntegration/BuildSystemManager.swift

@@ -1471,6 +1471,15 @@ fileprivate extension TextDocumentSourceKitOptionsResponse {
   /// This removes compiler arguments that produce output files and adds arguments to eg. allow errors and index the
   /// file.
   func adjustArgsForSemanticSwiftFunctionality(fileToIndex: DocumentURI) -> TextDocumentSourceKitOptionsResponse {
+    // Technically, `-o` and the output file don't need to be separated by a space. Eg. `swiftc -oa file.swift` is
+    // valid and will write to an output file named `a`.
+    // We can't support that because the only way to know that `-output-file-map` is a different flag and not an option
+    // to write to an output file named `utput-file-map` is to know all compiler arguments of `swiftc`, which we don't.
+    let outputPathOption = CompilerCommandLineOption.option("o", [.singleDash], [.separatedBySpace])
+
+    let indexUnitOutputPathOption =
+      CompilerCommandLineOption.option("index-unit-output-path", [.singleDash], [.separatedBySpace])
+
     let optionsToRemove: [CompilerCommandLineOption] = [
       .flag("c", [.singleDash]),
       .flag("disable-cmo", [.singleDash]),
@@ -1498,11 +1507,7 @@ fileprivate extension TextDocumentSourceKitOptionsResponse {
       .option("emit-package-module-interface-path", [.singleDash], [.separatedBySpace]),
       .option("emit-private-module-interface-path", [.singleDash], [.separatedBySpace]),
       .option("num-threads", [.singleDash], [.separatedBySpace]),
-      // Technically, `-o` and the output file don't need to be separated by a space. Eg. `swiftc -oa file.swift` is
-      // valid and will write to an output file named `a`.
-      // We can't support that because the only way to know that `-output-file-map` is a different flag and not an option
-      // to write to an output file named `utput-file-map` is to know all compiler arguments of `swiftc`, which we don't.
-      .option("o", [.singleDash], [.separatedBySpace]),
+      outputPathOption,
       .option("output-file-map", [.singleDash], [.separatedBySpace, .separatedByEqualSign]),
     ]
 
@@ -1534,6 +1539,15 @@ fileprivate extension TextDocumentSourceKitOptionsResponse {
 
     result += supplementalClangIndexingArgs.flatMap { ["-Xcc", $0] }
 
+    if let outputPathIndex = compilerArguments.lastIndex(where: { outputPathOption.matches(argument: $0) != nil }),
+      compilerArguments.allSatisfy({ indexUnitOutputPathOption.matches(argument: $0) == nil }),
+      outputPathIndex + 1 < compilerArguments.count
+    {
+      // The original compiler arguments contained `-o` to specify the output file but we have stripped that away.
+      // Re-introduce the output path as `-index-unit-output-path` so that we have an output path for the unit file.
+      result += ["-index-unit-output-path", compilerArguments[outputPathIndex + 1]]
+    }
+
     var adjusted = self
     adjusted.compilerArguments = result
     return adjusted

Sources/SKTestSupport/CustomBuildServerTestProject.swift

@@ -277,6 +277,7 @@ package final class CustomBuildServerTestProject<BuildServer: CustomBuildServer>
     options: SourceKitLSPOptions? = nil,
     hooks: Hooks = Hooks(),
     enableBackgroundIndexing: Bool = false,
+    pollIndex: Bool = true,
     testScratchDir: URL? = nil,
     testName: String = #function
   ) async throws {
@@ -295,6 +296,11 @@ package final class CustomBuildServerTestProject<BuildServer: CustomBuildServer>
       testScratchDir: testScratchDir,
       testName: testName
     )
+
+    if pollIndex {
+      // Wait for the indexstore-db to finish indexing
+      try await testClient.send(SynchronizeRequest(index: true))
+    }
   }
 
   package func buildServer(file: StaticString = #filePath, line: UInt = #line) throws -> BuildServer {

Tests/SourceKitLSPTests/BackgroundIndexingTests.swift

@@ -1978,7 +1978,8 @@ final class BackgroundIndexingTests: XCTestCase {
         """
       ],
       buildServer: BuildServer.self,
-      enableBackgroundIndexing: true
+      enableBackgroundIndexing: true,
+      pollIndex: false
     )
     let fileUrl = try XCTUnwrap(project.uri(for: "Test.swift").fileURL)
 
@@ -2141,7 +2142,6 @@ final class BackgroundIndexingTests: XCTestCase {
       buildServer: BuildServer.self,
       enableBackgroundIndexing: true
     )
-    try await project.testClient.send(SynchronizeRequest(index: true))
 
     let symbols = try await project.testClient.send(WorkspaceSymbolsRequest(query: "myTestFunc"))
     XCTAssertEqual(
@@ -2220,13 +2220,9 @@ final class BackgroundIndexingTests: XCTestCase {
       }
 
       func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse {
-        return initializationResponse(
-          initializeData: SourceKitInitializeBuildResponseData(
-            indexDatabasePath: try projectRoot.appendingPathComponent("index-db").filePath,
-            indexStorePath: try projectRoot.appendingPathComponent("index-store").filePath,
-            prepareProvider: true,
-            sourceKitOptionsProvider: true
-          )
+        return try initializationResponseSupportingBackgroundIndexing(
+          projectRoot: projectRoot,
+          outputPathsProvider: false
         )
       }
 
@@ -2264,7 +2260,6 @@ final class BackgroundIndexingTests: XCTestCase {
       enableBackgroundIndexing: true,
       testScratchDir: scratchDirectory
     )
-    try await project.testClient.send(SynchronizeRequest(index: true))
 
     // Ensure that changing `/private/tmp/.../test.c` only causes `/tmp/.../test.c` to be indexed, not
     // `/private/tmp/.../test.c`.
@@ -2375,7 +2370,6 @@ final class BackgroundIndexingTests: XCTestCase {
       buildServer: BuildServer.self,
       enableBackgroundIndexing: true
     )
-    try await project.testClient.send(SynchronizeRequest(index: true))
 
     let (libAUri, libAPositions) = try project.openDocument("LibA.swift")
     let libATypeHierarchyPrepare = try await project.testClient.send(
@@ -2493,7 +2487,6 @@ final class BackgroundIndexingTests: XCTestCase {
       buildServer: BuildServer.self,
       enableBackgroundIndexing: true
     )
-    try await project.testClient.send(SynchronizeRequest(index: true))
 
     let workspaceSymbolsBeforeUpdate = try await project.testClient.send(WorkspaceSymbolsRequest(query: "myTest"))
     XCTAssertEqual(workspaceSymbolsBeforeUpdate?.compactMap(\.symbolInformation?.name), ["myTestA", "myTestB"])
@@ -2539,6 +2532,59 @@ final class BackgroundIndexingTests: XCTestCase {
     // Check that we don't enter an infinite loop trying to index the circular symlink.
     try await project.testClient.send(SynchronizeRequest(index: true))
   }
+
+  func testBuildSystemDoesNotReturnIndexUnitOutputPath() async throws {
+    final class BuildSystem: CustomBuildServer {
+      let inProgressRequestsTracker = CustomBuildServerInProgressRequestTracker()
+      private let projectRoot: URL
+
+      required init(projectRoot: URL, connectionToSourceKitLSP: any LanguageServerProtocol.Connection) {
+        self.projectRoot = projectRoot
+      }
+
+      func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse {
+        return try initializationResponseSupportingBackgroundIndexing(
+          projectRoot: projectRoot,
+          outputPathsProvider: true
+        )
+      }
+
+      func buildTargetSourcesRequest(_ request: BuildTargetSourcesRequest) async throws -> BuildTargetSourcesResponse {
+        return BuildTargetSourcesResponse(items: [
+          SourcesItem(
+            target: .dummy,
+            sources: [
+              sourceItem(
+                for: projectRoot.appendingPathComponent("test.swift"),
+                outputPath: fakeOutputPath(for: "test.swift", in: "dummy")
+              )
+            ]
+          )
+        ])
+      }
+
+      func textDocumentSourceKitOptionsRequest(
+        _ request: TextDocumentSourceKitOptionsRequest
+      ) async throws -> TextDocumentSourceKitOptionsResponse? {
+        var arguments = [request.textDocument.uri.pseudoPath, "-o", fakeOutputPath(for: "test.swift", in: "dummy")]
+        if let defaultSDKPath {
+          arguments += ["-sdk", defaultSDKPath]
+        }
+        return TextDocumentSourceKitOptionsResponse(compilerArguments: arguments)
+      }
+    }
+
+    let project = try await CustomBuildServerTestProject(
+      files: [
+        "test.swift": "func myTestFunc() {}"
+      ],
+      buildServer: BuildSystem.self,
+      enableBackgroundIndexing: true
+    )
+
+    let symbols = try await project.testClient.send(WorkspaceSymbolsRequest(query: "myTestFu"))
+    XCTAssertEqual(symbols?.compactMap(\.symbolInformation?.name), ["myTestFunc()"])
+  }
 }
 
 extension HoverResponseContents {