Add support for a compile database file not at the root of a workspace

Sources/SKCore/CompilationDatabase.swift

@@ -15,6 +15,7 @@ import SKSupport
 
 import struct TSCBasic.AbsolutePath
 import protocol TSCBasic.FileSystem
+import struct TSCBasic.RelativePath
 import var TSCBasic.localFileSystem
 import func TSCBasic.resolveSymlinks
 
@@ -67,14 +68,28 @@ public protocol CompilationDatabase {
   var allCommands: AnySequence<Command> { get }
 }
 
-/// Loads the compilation database located in `directory`, if any.
+/// Loads the compilation database located in `directory`, if one can be found in `additionalSearchPaths` or in the default search paths of "." and "build".
 public func tryLoadCompilationDatabase(
   directory: AbsolutePath,
+  additionalSearchPaths: [RelativePath] = [],
   _ fileSystem: FileSystem = localFileSystem
 ) -> CompilationDatabase? {
+  let searchPaths =
+    additionalSearchPaths + [
+      // These default search paths match the behavior of `clangd`
+      try! RelativePath(validating: "."),
+      try! RelativePath(validating: "build"),
+    ]
   return
-    (try? JSONCompilationDatabase(directory: directory, fileSystem))
-    ?? (try? FixedCompilationDatabase(directory: directory, fileSystem))
+    try! searchPaths
+    .lazy
+    .map { directory.appending($0) }
+    .compactMap {
+      try
+        (JSONCompilationDatabase(directory: $0, fileSystem)
+        ?? FixedCompilationDatabase(directory: $0, fileSystem))
+    }
+    .first
 }
 
 /// Fixed clang-compatible compilation database (compile_flags.txt).
@@ -99,13 +114,21 @@ public struct FixedCompilationDatabase: CompilationDatabase, Equatable {
 }
 
 extension FixedCompilationDatabase {
-  public init(directory: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
+  /// Loads the compilation database located in `directory`, if any.
+  /// - Returns: `nil` if `compile_flags.txt` was not found
+  public init?(directory: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
     let path = directory.appending(component: "compile_flags.txt")
     try self.init(file: path, fileSystem)
   }
 
-  public init(file: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
+  /// Loads the compilation database from `file`
+  /// - Returns: `nil` if the file does not exist
+  public init?(file: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
     self.directory = file.dirname
+
+    guard fileSystem.exists(file) else {
+      return nil
+    }
     let bytes = try fileSystem.readFileContents(file)
 
     var fixedArgs: [String] = ["clang"]
@@ -185,12 +208,20 @@ extension JSONCompilationDatabase: Codable {
 }
 
 extension JSONCompilationDatabase {
-  public init(directory: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
+  /// Loads the compilation database located in `directory`, if any.
+  ///
+  /// - Returns: `nil` if `compile_commands.json` was not found
+  public init?(directory: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
     let path = directory.appending(component: "compile_commands.json")
     try self.init(file: path, fileSystem)
   }
 
-  public init(file: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
+  /// Loads the compilation database from `file`
+  /// - Returns: `nil` if the file does not exist
+  public init?(file: AbsolutePath, _ fileSystem: FileSystem = localFileSystem) throws {
+    guard fileSystem.exists(file) else {
+      return nil
+    }
     let bytes = try fileSystem.readFileContents(file)
     try bytes.withUnsafeData { data in
       self = try JSONDecoder().decode(JSONCompilationDatabase.self, from: data)

Sources/SKCore/CompilationDatabaseBuildSystem.swift

@@ -19,6 +19,7 @@ import SKSupport
 import struct Foundation.URL
 import struct TSCBasic.AbsolutePath
 import protocol TSCBasic.FileSystem
+import struct TSCBasic.RelativePath
 import var TSCBasic.localFileSystem
 
 /// A `BuildSystem` based on loading clang-compatible compilation database(s).
@@ -44,6 +45,8 @@ public actor CompilationDatabaseBuildSystem {
 
   let projectRoot: AbsolutePath?
 
+  let searchPaths: [RelativePath]
+
   let fileSystem: FileSystem
 
   /// The URIs for which the delegate has registered for change notifications,
@@ -70,11 +73,12 @@ public actor CompilationDatabaseBuildSystem {
     return nil
   }
 
-  public init(projectRoot: AbsolutePath? = nil, fileSystem: FileSystem = localFileSystem) {
+  public init(projectRoot: AbsolutePath? = nil, searchPaths: [RelativePath], fileSystem: FileSystem = localFileSystem) {
     self.fileSystem = fileSystem
     self.projectRoot = projectRoot
+    self.searchPaths = searchPaths
     if let path = projectRoot {
-      self.compdb = tryLoadCompilationDatabase(directory: path, fileSystem)
+      self.compdb = tryLoadCompilationDatabase(directory: path, additionalSearchPaths: searchPaths, fileSystem)
     }
   }
 }
@@ -122,7 +126,7 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
       var dir = path
       while !dir.isRoot {
         dir = dir.parentDirectory
-        if let db = tryLoadCompilationDatabase(directory: dir, fileSystem) {
+        if let db = tryLoadCompilationDatabase(directory: dir, additionalSearchPaths: searchPaths, fileSystem) {
           compdb = db
           break
         }
@@ -150,7 +154,11 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
   private func reloadCompilationDatabase() async {
     guard let projectRoot = self.projectRoot else { return }
 
-    self.compdb = tryLoadCompilationDatabase(directory: projectRoot, self.fileSystem)
+    self.compdb = tryLoadCompilationDatabase(
+      directory: projectRoot,
+      additionalSearchPaths: searchPaths,
+      self.fileSystem
+    )
 
     if let delegate = self.delegate {
       var changedFiles = Set<DocumentURI>()

Sources/SKTestSupport/SKSwiftPMTestWorkspace.swift

@@ -55,7 +55,7 @@ public final class SKSwiftPMTestWorkspace {
   /// Connection to the language server.
   public let testClient: TestSourceKitLSPClient
 
-  /// When `testServer` is not `nil`, the workspace will be opened in that server, otherwise a new server will be created for the workspace
+  /// When `testClient` is not `nil`, the workspace will be opened in that client's server, otherwise a new client will be created for the workspace
   public init(
     projectDir: URL,
     tmpDir: URL,

Sources/SKTestSupport/SKTibsTestWorkspace.swift

@@ -24,6 +24,7 @@ import XCTest
 import enum PackageLoading.Platform
 import struct PackageModel.BuildFlags
 import struct TSCBasic.AbsolutePath
+import struct TSCBasic.RelativePath
 
 public typealias URL = Foundation.URL
 
@@ -83,7 +84,10 @@ public final class SKTibsTestWorkspace {
 
   func initWorkspace(clientCapabilities: ClientCapabilities) async throws {
     let buildPath = try AbsolutePath(validating: builder.buildRoot.path)
-    let buildSystem = CompilationDatabaseBuildSystem(projectRoot: buildPath)
+    let buildSystem = CompilationDatabaseBuildSystem(
+      projectRoot: buildPath,
+      searchPaths: try [RelativePath(validating: ".")]
+    )
     let indexDelegate = SourceKitIndexDelegate()
     tibsWorkspace.delegate = indexDelegate
 

Sources/SourceKitLSP/SourceKitServer+Options.swift

@@ -16,6 +16,7 @@ import SKCore
 import SKSupport
 
 import struct TSCBasic.AbsolutePath
+import struct TSCBasic.RelativePath
 
 extension SourceKitServer {
 
@@ -29,6 +30,9 @@ extension SourceKitServer {
     /// Additional arguments to pass to `clangd` on the command-line.
     public var clangdOptions: [String]
 
+    /// Additional paths to search for a compilation database, relative to a workspace root.
+    public var compilationDatabaseSearchPaths: [RelativePath]
+
     /// Additional options for the index.
     public var indexOptions: IndexOptions
 
@@ -48,13 +52,15 @@ extension SourceKitServer {
     public init(
       buildSetup: BuildSetup = .default,
       clangdOptions: [String] = [],
+      compilationDatabaseSearchPaths: [RelativePath] = [],
       indexOptions: IndexOptions = .init(),
       completionOptions: SKCompletionOptions = .init(),
       generatedInterfacesPath: AbsolutePath = defaultDirectoryForGeneratedInterfaces,
       swiftPublishDiagnosticsDebounceDuration: TimeInterval = 2 /* 2s */
     ) {
       self.buildSetup = buildSetup
       self.clangdOptions = clangdOptions
+      self.compilationDatabaseSearchPaths = compilationDatabaseSearchPaths
       self.indexOptions = indexOptions
       self.completionOptions = completionOptions
       self.generatedInterfacesPath = generatedInterfacesPath

Sources/SourceKitLSP/SourceKitServer.swift

@@ -597,7 +597,7 @@ private var notificationIDForLogging: Int = 0
 
 /// On every call, returns a new unique number that can be used to identify a notification.
 ///
-/// This is needed so we can consistently refer to a notification using the `category` of the logger. 
+/// This is needed so we can consistently refer to a notification using the `category` of the logger.
 /// Requests don't need this since they already have a unique ID in the LSP protocol.
 private func getNextNotificationIDForLogging() -> Int {
   return notificationIDForLoggingLock.withLock {
@@ -648,7 +648,7 @@ extension SourceKitServer: MessageHandler {
       await self.withLanguageServiceAndWorkspace(for: notification, notificationHandler: self.willSaveDocument)
     case let notification as DidSaveTextDocumentNotification:
       await self.withLanguageServiceAndWorkspace(for: notification, notificationHandler: self.didSaveDocument)
-      // IMPORTANT: When adding a new entry to this switch, also add it to the `TaskMetadata` initializer.
+    // IMPORTANT: When adding a new entry to this switch, also add it to the `TaskMetadata` initializer.
     default:
       break
     }
@@ -771,7 +771,7 @@ extension SourceKitServer: MessageHandler {
         requestHandler: self.documentDiagnostic,
         fallback: .full(.init(items: []))
       )
-      // IMPORTANT: When adding a new entry to this switch, also add it to the `TaskMetadata` initializer.
+    // IMPORTANT: When adding a new entry to this switch, also add it to the `TaskMetadata` initializer.
     default:
       reply(.failure(ResponseError.methodNotFound(R.method)))
     }
@@ -860,6 +860,7 @@ extension SourceKitServer {
       capabilityRegistry: capabilityRegistry,
       toolchainRegistry: self.toolchainRegistry,
       buildSetup: self.options.buildSetup,
+      compilationDatabaseSearchPaths: self.options.compilationDatabaseSearchPaths,
       indexOptions: self.options.indexOptions,
       reloadPackageStatusCallback: { status in
         guard capabilityRegistry.clientCapabilities.window?.workDoneProgress ?? false else {

Sources/SourceKitLSP/Workspace.swift

@@ -18,6 +18,7 @@ import SKSupport
 import SKSwiftPMWorkspace
 
 import struct TSCBasic.AbsolutePath
+import struct TSCBasic.RelativePath
 
 /// Same as `??` but allows the right-hand side of the operator to 'await'.
 fileprivate func firstNonNil<T>(_ optional: T?, _ defaultValue: @autoclosure () async throws -> T) async rethrows -> T {
@@ -102,6 +103,7 @@ public final class Workspace {
     capabilityRegistry: CapabilityRegistry,
     toolchainRegistry: ToolchainRegistry,
     buildSetup: BuildSetup,
+    compilationDatabaseSearchPaths: [RelativePath],
     indexOptions: IndexOptions = IndexOptions(),
     reloadPackageStatusCallback: @escaping (ReloadPackageStatus) async -> Void
   ) async throws {
@@ -117,7 +119,7 @@ public final class Workspace {
       ) {
         buildSystem = swiftpm
       } else {
-        buildSystem = CompilationDatabaseBuildSystem(projectRoot: rootPath)
+        buildSystem = CompilationDatabaseBuildSystem(projectRoot: rootPath, searchPaths: compilationDatabaseSearchPaths)
       }
     } else {
       // We assume that workspaces are directories. This is only true for URLs not for URIs in general.

Sources/sourcekit-lsp/SourceKitLSP.swift

@@ -22,6 +22,7 @@ import SKSupport
 import SourceKitLSP
 
 import struct TSCBasic.AbsolutePath
+import struct TSCBasic.RelativePath
 import var TSCBasic.localFileSystem
 
 extension AbsolutePath: ExpressibleByArgument {
@@ -48,6 +49,18 @@ extension AbsolutePath: ExpressibleByArgument {
   }
 }
 
+extension RelativePath: ExpressibleByArgument {
+  public init?(argument: String) {
+    let path = try? RelativePath(validating: argument)
+
+    guard let path = path else {
+      return nil
+    }
+
+    self = path
+  }
+}
+
 extension PathPrefixMapping: ExpressibleByArgument {
   public init?(argument: String) {
     guard let eqIndex = argument.firstIndex(of: "=") else { return nil }
@@ -137,6 +150,14 @@ struct SourceKitLSP: ParsableCommand {
   )
   var indexPrefixMappings = [PathPrefixMapping]()
 
+  @Option(
+    name: .customLong("compilation-db-search-path"),
+    parsing: .singleValue,
+    help:
+      "Specify a relative path where sourcekit-lsp should search for `compile_commands.json` or `compile_flags.txt` relative to the root of a workspace. Multiple search paths may be specified by repeating this option."
+  )
+  var compilationDatabaseSearchPaths = [RelativePath]()
+
   @Option(
     help: "Specify the directory where generated interfaces will be stored"
   )
@@ -157,6 +178,7 @@ struct SourceKitLSP: ParsableCommand {
     serverOptions.buildSetup.flags.linkerFlags = buildFlagsLinker
     serverOptions.buildSetup.flags.swiftCompilerFlags = buildFlagsSwift
     serverOptions.clangdOptions = clangdOptions
+    serverOptions.compilationDatabaseSearchPaths = compilationDatabaseSearchPaths
     serverOptions.indexOptions.indexStorePath = indexStorePath
     serverOptions.indexOptions.indexDatabasePath = indexDatabasePath
     serverOptions.indexOptions.indexPrefixMappings = indexPrefixMappings