[swiftpm] Handle symlinks in the workspace path

Previously we would fail to get settings if the path didn't match
exactly. For now, we try first with the given path, then fallback to the
realpath (and we always realpath the workspace).

Author: benlangmuir

Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift

@@ -67,7 +67,7 @@ public final class SwiftPMWorkspace {
       throw Error.noManifest(workspacePath: workspacePath)
     }
 
-    self.packageRoot = packageRoot
+    self.packageRoot = resolveSymlinks(packageRoot)
 
     guard let destinationToolchainBinDir = toolchainRegistry.default?.path?.appending(components: "usr", "bin") else {
         throw Error.cannotDetermineHostToolchain
@@ -199,7 +199,7 @@ extension SwiftPMWorkspace: BuildSystem {
       return nil
     }
 
-    if let td = self.fileToTarget[path] {
+    if let td = targetDescription(for: path) {
       return settings(for: path, language, td)
     }
 
@@ -213,6 +213,21 @@ extension SwiftPMWorkspace: BuildSystem {
 
     return nil
   }
+
+  /// Returns the resolved target description for the given file, if one is known.
+  func targetDescription(for file: AbsolutePath) -> TargetBuildDescription? {
+    if let td = fileToTarget[file] {
+      return td
+    }
+
+    let realpath = resolveSymlinks(file)
+    if realpath != file, let td = fileToTarget[realpath] {
+      fileToTarget[file] = td
+      return td
+    }
+
+    return nil
+  }
 }
 
 extension SwiftPMWorkspace {
@@ -239,26 +254,44 @@ extension SwiftPMWorkspace {
 
   /// Retrieve settings for a package manifest (Package.swift).
   func settings(forPackageManifest path: AbsolutePath) -> FileBuildSettings? {
-    for package in packageGraph.packages where path == package.manifest.path {
+    func impl(_ path: AbsolutePath) -> FileBuildSettings? {
+      for package in packageGraph.packages where path == package.manifest.path {
         let compilerArgs = workspace.interpreterFlags(for: package.path) + [path.pathString]
         return FileBuildSettings(
           preferredToolchain: nil,
           compilerArguments: compilerArgs
         )
+      }
+      return nil
     }
-    return nil
+    
+    if let result = impl(path) { 
+      return result
+    }
+
+    let canonicalPath = resolveSymlinks(path)
+    return canonicalPath == path ? nil : impl(canonicalPath)
   }
 
   /// Retrieve settings for a given header file.
   public func settings(forHeader path: AbsolutePath, _ language: Language) -> FileBuildSettings? {
-    var dir = path.parentDirectory
-    while !dir.isRoot {
-      if let td = sourceDirToTarget[dir] {
-        return settings(for: path, language, td)
+    func impl(_ path: AbsolutePath) -> FileBuildSettings? {
+      var dir = path.parentDirectory
+      while !dir.isRoot {
+        if let td = sourceDirToTarget[dir] {
+          return settings(for: path, language, td)
+        }
+        dir = dir.parentDirectory
       }
-      dir = dir.parentDirectory
+      return nil
     }
-    return nil
+    
+    if let result = impl(path) { 
+      return result
+    }
+
+    let canonicalPath = resolveSymlinks(path)
+    return canonicalPath == path ? nil : impl(canonicalPath)
   }
 
   /// Retrieve settings for the given swift file, which is part of a known target build description.

Tests/SKSwiftPMWorkspaceTests/SwiftPMWorkspaceTests.swift

@@ -90,7 +90,7 @@ final class SwiftPMWorkspaceTests: XCTestCase {
             targets: [.target(name: "lib", dependencies: [])])
           """
     ])
-    let packageRoot = tempDir.path.appending(component: "pkg")
+    let packageRoot = resolveSymlinks(tempDir.path.appending(component: "pkg"))
     let tr = ToolchainRegistry.shared
     let ws = try! SwiftPMWorkspace(
       workspacePath: packageRoot,
@@ -183,7 +183,7 @@ final class SwiftPMWorkspaceTests: XCTestCase {
       fileSystem: fs,
       buildSetup: TestSourceKitServer.buildSetup)
 
-    let source = packageRoot.appending(component: "Package.swift")
+    let source = resolveSymlinks(packageRoot.appending(component: "Package.swift"))
     let arguments = ws.settings(for: source.asURL, .swift)!.compilerArguments
 
     check("-swift-version", "4.2", arguments: arguments)
@@ -204,7 +204,7 @@ final class SwiftPMWorkspaceTests: XCTestCase {
             targets: [.target(name: "lib", dependencies: [])])
           """
     ])
-    let packageRoot = tempDir.path.appending(component: "pkg")
+    let packageRoot = resolveSymlinks(tempDir.path.appending(component: "pkg"))
     let tr = ToolchainRegistry.shared
     let ws = try! SwiftPMWorkspace(
       workspacePath: packageRoot,
@@ -243,7 +243,7 @@ final class SwiftPMWorkspaceTests: XCTestCase {
             ])
           """
     ])
-    let packageRoot = tempDir.path.appending(component: "pkg")
+    let packageRoot = resolveSymlinks(tempDir.path.appending(component: "pkg"))
     let tr = ToolchainRegistry.shared
     let ws = try! SwiftPMWorkspace(
       workspacePath: packageRoot,
@@ -314,7 +314,7 @@ final class SwiftPMWorkspaceTests: XCTestCase {
             cxxLanguageStandard: .cxx14)
           """
     ])
-    let packageRoot = tempDir.path.appending(component: "pkg")
+    let packageRoot = resolveSymlinks(tempDir.path.appending(component: "pkg"))
     let tr = ToolchainRegistry.shared
     let ws = try! SwiftPMWorkspace(
       workspacePath: packageRoot,
@@ -393,6 +393,99 @@ final class SwiftPMWorkspaceTests: XCTestCase {
     check("-target", Triple.hostTriple.tripleString, arguments: arguments)
 #endif
   }
+
+  func testSymlinkInWorkspaceSwift() {
+    // FIXME: should be possible to use InMemoryFileSystem.
+    let fs = localFileSystem
+    let tempDir = try! TemporaryDirectory(removeTreeOnDeinit: true)
+
+    try! fs.createFiles(root: tempDir.path, files: [
+      "pkg_real/Sources/lib/a.swift": "",
+      "pkg_real/Package.swift": """
+      // swift-tools-version:4.2
+      import PackageDescription
+      let package = Package(name: "a", products: [], dependencies: [],
+      targets: [.target(name: "lib", dependencies: [])])
+      """
+    ])
+    let packageRoot = tempDir.path.appending(component: "pkg")
+
+    try! FileManager.default.createSymbolicLink(
+      atPath: packageRoot.pathString,
+      withDestinationPath: "pkg_real")
+
+    let tr = ToolchainRegistry.shared
+    let ws = try! SwiftPMWorkspace(
+      workspacePath: packageRoot,
+      toolchainRegistry: tr,
+      fileSystem: fs,
+      buildSetup: TestSourceKitServer.buildSetup)
+
+    let aswift1 = packageRoot.appending(components: "Sources", "lib", "a.swift")
+    let aswift2 = tempDir.path
+      .appending(component: "pkg_real")
+      .appending(components: "Sources", "lib", "a.swift")
+    let manifest = packageRoot.appending(components: "Package.swift")
+
+    let arguments1 = ws.settings(for: aswift1.asURL, .swift)?.compilerArguments
+    let arguments2 = ws.settings(for: aswift2.asURL, .swift)?.compilerArguments
+    XCTAssertNotNil(arguments1)
+    XCTAssertNotNil(arguments2)
+    XCTAssertEqual(arguments1, arguments2)
+
+    checkNot(aswift1.pathString, arguments: arguments1 ?? [])
+    check(resolveSymlinks(aswift1).pathString, arguments: arguments1 ?? [])
+
+    let argsManifest = ws.settings(for: manifest.asURL, .swift)?.compilerArguments
+    XCTAssertNotNil(argsManifest)
+
+    checkNot(manifest.pathString, arguments: argsManifest ?? [])
+    check(resolveSymlinks(manifest).pathString, arguments: argsManifest ?? [])
+  }
+
+  func testSymlinkInWorkspaceCXX() {
+    // FIXME: should be possible to use InMemoryFileSystem.
+    let fs = localFileSystem
+    let tempDir = try! TemporaryDirectory(removeTreeOnDeinit: true)
+    try! fs.createFiles(root: tempDir.path, files: [
+      "pkg_real/Sources/lib/a.cpp": "",
+      "pkg_real/Sources/lib/b.cpp": "",
+      "pkg_real/Sources/lib/include/a.h": "",
+      "pkg_real/Package.swift": """
+          // swift-tools-version:4.2
+          import PackageDescription
+          let package = Package(name: "a", products: [], dependencies: [],
+            targets: [.target(name: "lib", dependencies: [])],
+            cxxLanguageStandard: .cxx14)
+          """
+    ])
+
+    let packageRoot = tempDir.path.appending(component: "pkg")
+
+    try! FileManager.default.createSymbolicLink(
+      atPath: packageRoot.pathString,
+      withDestinationPath: "pkg_real")
+
+    let tr = ToolchainRegistry.shared
+    let ws = try! SwiftPMWorkspace(
+      workspacePath: packageRoot,
+      toolchainRegistry: tr,
+      fileSystem: fs,
+      buildSetup: TestSourceKitServer.buildSetup)
+
+    let acxx = packageRoot.appending(components: "Sources", "lib", "a.cpp")
+    let ah = packageRoot.appending(components: "Sources", "lib", "include", "a.h")
+
+    let argsCxx = ws.settings(for: acxx.asURL, .cpp)?.compilerArguments
+    XCTAssertNotNil(argsCxx)
+    check(acxx.pathString, arguments: argsCxx ?? [])
+    checkNot(resolveSymlinks(acxx).pathString, arguments: argsCxx ?? [])
+
+    let argsH = ws.settings(for: ah.asURL, .cpp)?.compilerArguments
+    XCTAssertNotNil(argsH)
+    checkNot(ah.pathString, arguments: argsH ?? [])
+    check(resolveSymlinks(ah).pathString, arguments: argsH ?? [])
+  }
 }
 
 private func checkNot(