Add new 'VirtualPath' variant for a driver-computed build artifact with known contents

Similarly to a 'temporaryWithKnownContents', but at an explicitly-determined-by-the-driver 'AbsolutePath'. This is useful for when the driver is able to determine that build planning will produce an input to compilation which must be placed in a specific location. For example, the chained bridging header content and output path are determined during build planning (specifically, dependency scanning) and must be fed into compilation tasks as inputs. This new file type will allow the driver to compute the new file and its contents and then have them get written to disk when resolving input paths to said compilation tasks.

Author: artemcm

Sources/SwiftDriver/Driver/Driver.swift

@@ -330,7 +330,7 @@ public struct Driver {
     case .relative(let path):
       let cwd = workingDirectory ?? fileSystem.currentWorkingDirectory
       return cwd.map { AbsolutePath($0, path) }
-    case .standardInput, .standardOutput, .temporary, .temporaryWithKnownContents, .fileList:
+    case .standardInput, .standardOutput, .temporary, .temporaryWithKnownContents, .fileList, .buildArtifactWithKnownContents:
       fatalError("Frontend target information will never include a path of this type.")
     }
   }
@@ -3087,15 +3087,11 @@ extension Driver {
     chainedBridgingHeader: ChainedBridgingHeaderFile?) throws -> VirtualPath.Handle? {
     // handle chained bridging header.
     if let chainedHeader = chainedBridgingHeader, !chainedHeader.path.isEmpty {
-      let path = try VirtualPath(path: chainedHeader.path)
-      let dirExists = try fileSystem.exists(path.parentDirectory)
-      if !dirExists, let dirToCreate = path.parentDirectory.absolutePath {
-        try fileSystem.createDirectory(dirToCreate, recursive: true)
-      }
-      try fileSystem.writeFileContents(path,
-                                       bytes: ByteString(encodingAsUTF8: chainedHeader.content),
-                                       atomically: true)
-      return path.intern()
+      let path = try AbsolutePath(validating: chainedHeader.path)
+      if !fileSystem.exists(path.parentDirectory) {
+        try fileSystem.createDirectory(path.parentDirectory, recursive: true)
+      }
+      return try VirtualPath.createBuildProductFileWithKnownContents(path, chainedHeader.content.data(using: .utf8)!).intern()
     }
     return originalObjCHeaderFile
   }

Sources/SwiftDriver/Execution/ArgsResolver.swift

@@ -134,7 +134,7 @@ public final class ArgsResolver {
         try createFileList(path: actualPath, contents: items)
       case let .fileList(_, .outputFileMap(map)):
         try createFileList(path: actualPath, outputFileMap: map)
-      case .relative, .absolute, .standardInput, .standardOutput:
+      case .relative, .absolute, .standardInput, .standardOutput, .buildArtifactWithKnownContents:
         fatalError("Not a temporary path.")
       }
 
@@ -143,6 +143,12 @@ public final class ArgsResolver {
       return result
     }
 
+    // First time resolving a build product with a known path and driver-computed
+    // contents, write it to the filesystem.
+    if case let .buildArtifactWithKnownContents(absolutePath, contents) = path {
+      try fileSystem.writeFileContents(absolutePath, bytes: .init(contents))
+    }
+
     // Otherwise, return the path.
     let result = path.name
     pathMapping[path] = result

Sources/SwiftDriver/Utilities/VirtualPath.swift

@@ -47,6 +47,9 @@ public enum VirtualPath: Hashable {
   /// Standard output
   case standardOutput
 
+  /// ACTODO: Comment
+  case buildArtifactWithKnownContents(AbsolutePath, Data)
+
   /// We would like to direct clients to use the temporary file creation utilities `createUniqueTemporaryFile`, etc.
   /// To ensure temporary files are unique.
   /// TODO: If/When Swift gains enum access control, we can prohibit direct instantiation of temporary file cases,
@@ -72,6 +75,8 @@ public enum VirtualPath: Hashable {
     case .relative(let path), .temporary(let path),
          .temporaryWithKnownContents(let path, _), .fileList(let path, _):
       return path.extension
+    case .buildArtifactWithKnownContents(let path, _):
+      return path.extension
     case .absolute(let path):
       return path.extension
     case .standardInput, .standardOutput:
@@ -82,7 +87,7 @@ public enum VirtualPath: Hashable {
   /// Whether this virtual path is to a temporary.
   public var isTemporary: Bool {
     switch self {
-    case .relative, .absolute, .standardInput, .standardOutput:
+    case .relative, .absolute, .standardInput, .standardOutput, .buildArtifactWithKnownContents:
       return false
     case .temporary, .temporaryWithKnownContents, .fileList:
       return true
@@ -91,7 +96,7 @@ public enum VirtualPath: Hashable {
 
   public var absolutePath: AbsolutePath? {
     switch self {
-    case let .absolute(absolutePath):
+    case .absolute(let absolutePath), .buildArtifactWithKnownContents(let absolutePath, _):
       return absolutePath
     case .relative, .temporary, .temporaryWithKnownContents, .fileList, .standardInput, .standardOutput:
       return nil
@@ -111,15 +116,15 @@ public enum VirtualPath: Hashable {
          .fileList(let name, _),
          .temporaryWithKnownContents(let name, _):
       return name
-    case .absolute, .relative, .standardInput, .standardOutput:
+    case .absolute, .relative, .standardInput, .standardOutput, .buildArtifactWithKnownContents:
       return nil
     }
   }
 
   /// Retrieve the basename of the path.
   public var basename: String {
     switch self {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return path.basename
     case .relative(let path), .temporary(let path), .temporaryWithKnownContents(let path, _), .fileList(let path, _):
       return path.basename
@@ -131,7 +136,7 @@ public enum VirtualPath: Hashable {
   /// Retrieve the basename of the path without the extension.
   public var basenameWithoutExt: String {
     switch self {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return path.basenameWithoutExt
     case .relative(let path), .temporary(let path), .temporaryWithKnownContents(let path, _), .fileList(let path, _):
       return path.basenameWithoutExt
@@ -143,7 +148,7 @@ public enum VirtualPath: Hashable {
   /// Retrieve the path to the parent directory.
   public var parentDirectory: VirtualPath {
     switch self {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return .absolute(path.parentDirectory)
     case .relative(let path):
       return .relative(try! RelativePath(validating: path.dirname))
@@ -162,7 +167,7 @@ public enum VirtualPath: Hashable {
   /// This should not be used with `.standardInput` or `.standardOutput`.
   public func appending(component: String) -> VirtualPath {
     switch self {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return .absolute(path.appending(component: component))
     case .relative(let path):
       return .relative(path.appending(component: component))
@@ -180,7 +185,7 @@ public enum VirtualPath: Hashable {
 
   public func appending(components: String...) -> VirtualPath {
     switch self {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return .absolute(path.appending(components: components))
     case .relative(let path):
       return .relative(path.appending(components: components))
@@ -201,7 +206,7 @@ public enum VirtualPath: Hashable {
   /// This should not be used with `.standardInput` or `.standardOutput`.
   public func appendingToBaseName(_ suffix: String) throws -> VirtualPath {
     switch self {
-    case let .absolute(path):
+    case let .absolute(path), .buildArtifactWithKnownContents(let path, _):
       return .absolute(try AbsolutePath(validating: path.pathString + suffix))
     case let .relative(path):
       return .relative(try RelativePath(validating: path.pathString + suffix))
@@ -297,6 +302,8 @@ extension VirtualPath {
       return path.pathString
     case .absolute(let path):
       return path.pathString
+    case .buildArtifactWithKnownContents(let path, _):
+      return "buildArtifactWithKnownContents:" + path.pathString
     case .temporary(let path):
       // N.B. Mangle in a discrimintor for temporaries so they intern apart
       // from normal kinds of paths.
@@ -429,6 +436,13 @@ extension VirtualPath {
   }
 }
 
+extension VirtualPath {
+  public static func createBuildProductFileWithKnownContents(_ path: AbsolutePath, _ data: Data)
+  throws -> VirtualPath {
+    return .buildArtifactWithKnownContents(path, data)
+  }
+}
+
 // MARK: Temporary File Creation
 
 /// Most client contexts require temporary files they request to be unique (e.g. auxiliary compile outputs).
@@ -511,7 +525,7 @@ extension VirtualPath.Handle: Hashable {}
 extension VirtualPath: Codable {
   private enum CodingKeys: String, CodingKey {
     case relative, absolute, standardInput, standardOutput, temporary,
-         temporaryWithKnownContents, fileList
+         temporaryWithKnownContents, buildProductWithKnownContents, fileList
   }
 
   public func encode(to encoder: Encoder) throws {
@@ -534,6 +548,10 @@ extension VirtualPath: Codable {
       var unkeyedContainer = container.nestedUnkeyedContainer(forKey: .temporaryWithKnownContents)
       try unkeyedContainer.encode(path)
       try unkeyedContainer.encode(contents)
+    case let .buildArtifactWithKnownContents(path, contents):
+      var unkeyedContainer = container.nestedUnkeyedContainer(forKey: .buildProductWithKnownContents)
+      try unkeyedContainer.encode(path)
+      try unkeyedContainer.encode(contents)
     case .fileList(let path, let fileList):
       var unkeyedContainer = container.nestedUnkeyedContainer(forKey: .fileList)
       try unkeyedContainer.encode(path)
@@ -568,6 +586,11 @@ extension VirtualPath: Codable {
       let path = try unkeyedValues.decode(RelativePath.self)
       let contents = try unkeyedValues.decode(Data.self)
       self = .temporaryWithKnownContents(path, contents)
+    case .buildProductWithKnownContents:
+      var unkeyedValues = try values.nestedUnkeyedContainer(forKey: key)
+      let path = try unkeyedValues.decode(AbsolutePath.self)
+      let contents = try unkeyedValues.decode(Data.self)
+      self = .buildArtifactWithKnownContents(path, contents)
     case .fileList:
       var unkeyedValues = try values.nestedUnkeyedContainer(forKey: key)
       let path = try unkeyedValues.decode(RelativePath.self)
@@ -593,7 +616,7 @@ public struct TextualVirtualPath: Codable, Hashable {
   public func encode(to encoder: Encoder) throws {
     var container = encoder.singleValueContainer()
     switch VirtualPath.lookup(self.path) {
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       try container.encode(path.pathString)
     case .relative(let path):
       try container.encode(path.pathString)
@@ -612,7 +635,7 @@ extension VirtualPath: CustomStringConvertible {
     case .relative(let path):
       return path.pathString
 
-    case .absolute(let path):
+    case .absolute(let path), .buildArtifactWithKnownContents(let path, _):
       return path.pathString
 
     case .standardInput, .standardOutput:
@@ -632,6 +655,8 @@ extension VirtualPath: CustomDebugStringConvertible {
       return ".relative(\(path.pathString))"
     case .absolute(let path):
       return ".absolute(\(path.pathString))"
+    case .buildArtifactWithKnownContents(let path, _):
+      return "buildProductWithKnownContents(\(path.pathString))"
     case .standardInput:
       return ".standardInput"
     case .standardOutput:
@@ -653,6 +678,8 @@ extension VirtualPath {
     switch self {
     case let .absolute(path):
       return .absolute(try AbsolutePath(validating: path.pathString.withoutExt(path.extension).appendingFileTypeExtension(fileType)))
+    case let .buildArtifactWithKnownContents(path, content):
+      return .buildArtifactWithKnownContents(try AbsolutePath(validating: path.pathString.withoutExt(path.extension).appendingFileTypeExtension(fileType)), content)
     case let .relative(path):
       return .relative(try RelativePath(validating: path.pathString.withoutExt(path.extension).appendingFileTypeExtension(fileType)))
     case let .temporary(path):
@@ -700,6 +727,8 @@ extension TSCBasic.FileSystem {
     switch path {
     case let .absolute(absPath):
       return try f(absPath)
+    case let .buildArtifactWithKnownContents(absPath, _):
+      return try f(absPath)
     case let .relative(relPath):
       guard let cwd = currentWorkingDirectory else {
         throw FileSystemError.noCurrentWorkingDirectory