Get compiler arguments for files in the Plugins folder

This uses the new API in SwiftPM introduced by swiftlang/swift-package-manager#6763 to get compiler arguments for a target instead of stitching them together in sourcekit-lsp.

Fixes swiftlang#664
rdar://102213837

Author: ahoppen

Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift

@@ -22,6 +22,7 @@ import PackageModel
 import SKCore
 import SKSupport
 import SourceControl
+import SwiftPM
 import Workspace
 
 import struct Basics.AbsolutePath
@@ -43,6 +44,20 @@ public enum ReloadPackageStatus {
   case end
 }
 
+/// A build target in SwiftPM
+public typealias SwiftBuildTarget = SwiftPM.BuildTarget
+
+/// A build target in `BuildServerProtocol`
+public typealias BuildServerTarget = BuildServerProtocol.BuildTarget
+
+extension SwiftBuildTarget {
+  func fixedCompileArguments() throws -> [String] {
+    var args = try self.compileArguments()
+    args += self.sources.map { $0.path }
+    return args
+  }
+}
+
 /// Swift Package Manager build system and workspace support.
 ///
 /// This class implements the `BuildSystem` interface to provide the build settings for a Swift
@@ -75,8 +90,8 @@ public actor SwiftPMWorkspace {
   public let buildParameters: BuildParameters
   let fileSystem: FileSystem
 
-  var fileToTarget: [AbsolutePath: TargetBuildDescription] = [:]
-  var sourceDirToTarget: [AbsolutePath: TargetBuildDescription] = [:]
+  var fileToTarget: [AbsolutePath: SwiftBuildTarget] = [:]
+  var sourceDirToTarget: [AbsolutePath: SwiftBuildTarget] = [:]
 
   /// The URIs for which the delegate has registered for change notifications,
   /// mapped to the language the delegate specified when registering for change notifications.
@@ -213,13 +228,13 @@ extension SwiftPMWorkspace {
     /// with only some properties modified.
     self.packageGraph = packageGraph
 
-    self.fileToTarget = [AbsolutePath: TargetBuildDescription](
+    self.fileToTarget = [AbsolutePath: SwiftBuildTarget](
       packageGraph.allTargets.flatMap { target in
         return target.sources.paths.compactMap {
-          guard let td = plan.targetMap[target] else {
+          guard let buildTarget = BuildDescription(buildPlan: plan).getBuildTarget(for: target) else {
             return nil
           }
-          return (key: $0, value: td)
+          return (key: $0, value: buildTarget)
         }
       },
       uniquingKeysWith: { td, _ in
@@ -228,12 +243,12 @@ extension SwiftPMWorkspace {
       }
     )
 
-    self.sourceDirToTarget = [AbsolutePath: TargetBuildDescription](
-      packageGraph.allTargets.compactMap { target in
-        guard let td = plan.targetMap[target] else {
+    self.sourceDirToTarget = [AbsolutePath: SwiftBuildTarget](
+      packageGraph.allTargets.compactMap { (target) -> (AbsolutePath, SwiftBuildTarget)? in
+        guard let buildTarget = BuildDescription(buildPlan: plan).getBuildTarget(for: target) else {
           return nil
         }
-        return (key: target.sources.root, value: td)
+        return (key: target.sources.root, value: buildTarget)
       },
       uniquingKeysWith: { td, _ in
         // FIXME: is there  a preferred target?
@@ -284,8 +299,11 @@ extension SwiftPMWorkspace: SKCore.BuildSystem {
       return nil
     }
 
-    if let td = try targetDescription(for: path) {
-      return try settings(for: path, language, td)
+    if let buildTarget = try buildTarget(for: path) {
+      return FileBuildSettings(
+        compilerArguments: try buildTarget.fixedCompileArguments(),
+        workingDirectory: workspacePath.pathString
+      )
     }
 
     if path.basename == "Package.swift" {
@@ -310,7 +328,7 @@ extension SwiftPMWorkspace: SKCore.BuildSystem {
   }
 
   /// Returns the resolved target description for the given file, if one is known.
-  private func targetDescription(for file: AbsolutePath) throws -> TargetBuildDescription? {
+  private func buildTarget(for file: AbsolutePath) throws -> SwiftBuildTarget? {
     if let td = fileToTarget[file] {
       return td
     }
@@ -359,7 +377,7 @@ extension SwiftPMWorkspace: SKCore.BuildSystem {
     guard let fileUrl = uri.fileURL else {
       return .unhandled
     }
-    if (try? targetDescription(for: AbsolutePath(validating: fileUrl.path))) != nil {
+    if (try? buildTarget(for: AbsolutePath(validating: fileUrl.path))) != nil {
       return .handled
     } else {
       return .unhandled
@@ -371,24 +389,6 @@ extension SwiftPMWorkspace {
 
   // MARK: Implementation details
 
-  /// Retrieve settings for the given file, which is part of a known target build description.
-  public func settings(
-    for path: AbsolutePath,
-    _ language: Language,
-    _ td: TargetBuildDescription
-  ) throws -> FileBuildSettings? {
-    switch (td, language) {
-    case (.swift(let td), .swift):
-      return try settings(forSwiftFile: path, td)
-    case (.clang, .swift):
-      return nil
-    case (.clang(let td), _):
-      return try settings(forClangFile: path, language, td)
-    default:
-      return nil
-    }
-  }
-
   /// Retrieve settings for a package manifest (Package.swift).
   private func settings(forPackageManifest path: AbsolutePath) throws -> FileBuildSettings? {
     func impl(_ path: AbsolutePath) -> FileBuildSettings? {
@@ -412,8 +412,11 @@ extension SwiftPMWorkspace {
     func impl(_ path: AbsolutePath) throws -> FileBuildSettings? {
       var dir = path.parentDirectory
       while !dir.isRoot {
-        if let td = sourceDirToTarget[dir] {
-          return try settings(for: path, language, td)
+        if let buildTarget = sourceDirToTarget[dir] {
+          return FileBuildSettings(
+            compilerArguments: try buildTarget.fixedCompileArguments(),
+            workingDirectory: workspacePath.pathString
+          )
         }
         dir = dir.parentDirectory
       }
@@ -428,36 +431,6 @@ extension SwiftPMWorkspace {
     return try canonicalPath == path ? nil : impl(canonicalPath)
   }
 
-  /// Retrieve settings for the given swift file, which is part of a known target build description.
-  public func settings(
-    forSwiftFile path: AbsolutePath,
-    _ td: SwiftTargetBuildDescription
-  ) throws -> FileBuildSettings {
-    // FIXME: this is re-implementing llbuild's constructCommandLineArgs.
-    var args: [String] = [
-      "-module-name",
-      td.target.c99name,
-      "-incremental",
-      "-emit-dependencies",
-      "-emit-module",
-      "-emit-module-path",
-      buildPath.appending(component: "\(td.target.c99name).swiftmodule").pathString,
-      // -output-file-map <path>
-    ]
-    if td.target.type == .library || td.target.type == .test {
-      args += ["-parse-as-library"]
-    }
-    args += ["-c"]
-    args += td.sources.map { $0.pathString }
-    args += ["-I", buildPath.pathString]
-    args += try td.compileArguments()
-
-    return FileBuildSettings(
-      compilerArguments: args,
-      workingDirectory: workspacePath.pathString
-    )
-  }
-
   /// Retrieve settings for the given C-family language file, which is part of a known target build
   /// description.
   ///

Tests/SKSwiftPMWorkspaceTests/SwiftPMWorkspaceTests.swift

@@ -694,6 +694,53 @@ final class SwiftPMWorkspaceTests: XCTestCase {
       assertEqual(await ws._packageRoot, try resolveSymlinks(tempDir.appending(component: "pkg")))
     }
   }
+
+  func testPluginArgs() async throws {
+    // FIXME: should be possible to use InMemoryFileSystem.
+    let fs = localFileSystem
+    try await withTemporaryDirectory(removeTreeOnDeinit: true) { tempDir in
+      try fs.createFiles(
+        root: tempDir,
+        files: [
+          "pkg/Plugins/MyPlugin/a.swift": "",
+          "pkg/Sources/lib/lib.swift": "",
+          "pkg/Package.swift": """
+          // swift-tools-version:5.7
+          import PackageDescription
+          let package = Package(
+            name: "a",
+            products: [],
+            dependencies: [],
+            targets: [
+              .target(name: "lib"),
+              .plugin(name: "MyPlugin", capability: .buildTool)
+            ]
+          )
+          """,
+        ]
+      )
+      let packageRoot = try resolveSymlinks(tempDir.appending(component: "pkg"))
+      let tr = ToolchainRegistry.shared
+      let ws = try await SwiftPMWorkspace(
+        workspacePath: packageRoot,
+        toolchainRegistry: tr,
+        fileSystem: fs,
+        buildSetup: SourceKitServer.Options.testDefault.buildSetup
+      )
+
+      let aswift = packageRoot.appending(components: "Plugins", "MyPlugin", "a.swift")
+      let hostTriple = await ws.buildParameters.targetTriple
+      let build = buildPath(root: packageRoot, platform: hostTriple.platformBuildPathComponent)
+
+      assertEqual(await ws.buildPath, build)
+      assertNotNil(await ws.indexStorePath)
+      let arguments = try await ws._settings(for: aswift.asURI, .swift)!.compilerArguments
+
+      check("-sdk", arguments: arguments)
+      check("-package-description-version", "5.7.0", arguments: arguments)
+      check(aswift.pathString, arguments: arguments)
+    }
+  }
 }
 
 private func checkNot(