FrontendJobHelpers.swift

//===--------------- FrontendJobHelpers.swift - Swift Frontend Job Common -===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import SwiftOptions

import class TSCBasic.LocalFileOutputByteStream
import class TSCBasic.TerminalController
import struct TSCBasic.RelativePath
import var TSCBasic.stderrStream

/// Whether we should produce color diagnostics by default.
fileprivate func shouldColorDiagnostics() -> Bool {
  guard let stderrStream = stderrStream.stream as? LocalFileOutputByteStream else {
    return false
  }

  return TerminalController.isTTY(stderrStream)
}

extension Driver {
  /// How the bridging header should be handled.
  enum BridgingHeaderHandling {
    /// Ignore the bridging header entirely.
    case ignored

    /// Parse the bridging header, even if other jobs will use a precompiled
    /// bridging header.
    ///
    /// This is typically used only when precompiling the bridging header.
    case parsed

    /// Use the precompiled bridging header.
    case precompiled
  }
  /// Whether the driver has already constructed a module dependency graph or is in the process
  /// of doing so
  enum ModuleDependencyGraphUse {
    /// Even though the driver may be in ExplicitModuleBuild mode, the dependency graph has not yet
    /// been constructed, omit processing module dependencies
    case dependencyScan
    /// If the driver is in Explicit Module Build mode, the dependency graph has been computed
    case computed
  }
  /// Add frontend options that are common to different frontend invocations.
  mutating func addCommonFrontendOptions(
    commandLine: inout [Job.ArgTemplate],
    inputs: inout [TypedVirtualPath],
    bridgingHeaderHandling: BridgingHeaderHandling = .precompiled,
    moduleDependencyGraphUse: ModuleDependencyGraphUse = .computed,
    isGeneratePCH: Bool = false
  ) throws {
    // Only pass -target to the REPL or immediate modes if it was explicitly
    // specified on the command line.
    switch compilerMode {
    case .standardCompile, .singleCompile, .batchCompile, .compilePCM, .dumpPCM:
      commandLine.appendFlag(.target)
      commandLine.appendFlag(targetTriple.triple)

    case .repl, .immediate:
      if parsedOptions.hasArgument(.target) {
        commandLine.appendFlag(.target)
        commandLine.appendFlag(targetTriple.triple)
      }
    case .intro:
      break
    }

    // If in ExplicitModuleBuild mode and the dependency graph has been computed, add module
    // dependencies.
    // May also be used for generation of the dependency graph itself in ExplicitModuleBuild mode.
    if (parsedOptions.contains(.driverExplicitModuleBuild) &&
          moduleDependencyGraphUse == .computed) {
      if isGeneratePCH {
        try addExplicitPCHBuildArguments(inputs: &inputs, commandLine: &commandLine)
      } else {
        try addExplicitModuleBuildArguments(inputs: &inputs, commandLine: &commandLine)
      }
    }

    if let variant = parsedOptions.getLastArgument(.targetVariant)?.asSingle {
      commandLine.appendFlag(.targetVariant)
      commandLine.appendFlag(Triple(variant, normalizing: true).triple)
    }

    // Enable address top-byte ignored in the ARM64 backend.
    if targetTriple.arch == .aarch64 {
      commandLine.appendFlag(.Xllvm)
      commandLine.appendFlag("-aarch64-use-tbi")
    }

    // Potentially unavailable enum cases are downgraded to a warning when building a
    // swiftmodule, to allow building a module (or module interface) for an older
    // deployment target than the framework itself.
    if isFrontendArgSupported(.warnOnPotentiallyUnavailableEnumCase) {
      if compilerOutputType == .swiftModule {
        commandLine.appendFlag(.warnOnPotentiallyUnavailableEnumCase)
      }
    }

    // Enable or disable ObjC interop appropriately for the platform
    if targetTriple.isDarwin {
      commandLine.appendFlag(.enableObjcInterop)
    } else {
      commandLine.appendFlag(.disableObjcInterop)
    }

    // Add flags for C++ interop
    try commandLine.appendLast(.enableExperimentalCxxInterop, from: &parsedOptions)
    try commandLine.appendLast(.cxxInteroperabilityMode, from: &parsedOptions)
    if let stdlibVariant = parsedOptions.getLastArgument(.experimentalCxxStdlib)?.asSingle {
      commandLine.appendFlag("-Xcc")
      commandLine.appendFlag("-stdlib=\(stdlibVariant)")
    }

    // Handle the CPU and its preferences.
    try commandLine.appendLast(.targetCpu, from: &parsedOptions)

    if let sdkPath = frontendTargetInfo.sdkPath?.path {
      commandLine.appendFlag(.sdk)
      commandLine.append(.path(VirtualPath.lookup(sdkPath)))
    }

    for args: (Option, Option) in [
          (.visualcToolsRoot, .visualcToolsVersion),
          (.windowsSdkRoot, .windowsSdkVersion)
        ] {
      let (rootArg, versionArg) = args
      if let value = parsedOptions.getLastArgument(rootArg)?.asSingle,
          isFrontendArgSupported(rootArg) {
        commandLine.appendFlag(rootArg.spelling)
        commandLine.appendPath(.init(value))
      }

      if let value = parsedOptions.getLastArgument(versionArg)?.asSingle,
          isFrontendArgSupported(versionArg) {
        commandLine.appendFlags(versionArg.spelling, value)
      }
    }

    try commandLine.appendAll(.I, from: &parsedOptions)
    try commandLine.appendAll(.F, .Fsystem, from: &parsedOptions)
    try commandLine.appendAll(.vfsoverlay, from: &parsedOptions)

    try commandLine.appendLast(.AssertConfig, from: &parsedOptions)
    try commandLine.appendLast(.autolinkForceLoad, from: &parsedOptions)

    if let colorOption = parsedOptions.last(for: .colorDiagnostics, .noColorDiagnostics) {
      commandLine.appendFlag(colorOption.option)
    } else if shouldColorDiagnostics() {
      commandLine.appendFlag(.colorDiagnostics)
    }
    try commandLine.appendLast(.fixitAll, from: &parsedOptions)
    try commandLine.appendLast(.warnSwift3ObjcInferenceMinimal, .warnSwift3ObjcInferenceComplete, from: &parsedOptions)
    try commandLine.appendLast(.warnImplicitOverrides, from: &parsedOptions)
    try commandLine.appendLast(.typoCorrectionLimit, from: &parsedOptions)
    try commandLine.appendLast(.enableAppExtension, from: &parsedOptions)
    try commandLine.appendLast(.enableLibraryEvolution, from: &parsedOptions)
    try commandLine.appendLast(.enableTesting, from: &parsedOptions)
    try commandLine.appendLast(.enablePrivateImports, from: &parsedOptions)
    try commandLine.appendLast(in: .g, from: &parsedOptions)
    try commandLine.appendLast(.debugInfoFormat, from: &parsedOptions)
    try commandLine.appendLast(.importUnderlyingModule, from: &parsedOptions)
    try commandLine.appendLast(.moduleCachePath, from: &parsedOptions)
    try commandLine.appendLast(.moduleLinkName, from: &parsedOptions)
    try commandLine.appendLast(.nostdimport, from: &parsedOptions)
    try commandLine.appendLast(.parseStdlib, from: &parsedOptions)
    try commandLine.appendLast(.solverMemoryThreshold, from: &parsedOptions)
    try commandLine.appendLast(.valueRecursionThreshold, from: &parsedOptions)
    try commandLine.appendLast(.warnSwift3ObjcInference, from: &parsedOptions)
    try commandLine.appendLast(.remarkLoadingModule, from: &parsedOptions)
    try commandLine.appendLast(.RpassEQ, from: &parsedOptions)
    try commandLine.appendLast(.RpassMissedEQ, from: &parsedOptions)
    try commandLine.appendLast(.suppressWarnings, from: &parsedOptions)
    try commandLine.appendLast(.profileGenerate, from: &parsedOptions)
    try commandLine.appendLast(.profileUse, from: &parsedOptions)
    try commandLine.appendLast(.profileCoverageMapping, from: &parsedOptions)
    try commandLine.appendLast(.warningsAsErrors, .noWarningsAsErrors, from: &parsedOptions)
    try commandLine.appendLast(.sanitizeEQ, from: &parsedOptions)
    try commandLine.appendLast(.sanitizeRecoverEQ, from: &parsedOptions)
    try commandLine.appendLast(.sanitizeAddressUseOdrIndicator, from: &parsedOptions)
    try commandLine.appendLast(.sanitizeCoverageEQ, from: &parsedOptions)
    try commandLine.appendLast(.static, from: &parsedOptions)
    try commandLine.appendLast(.swiftVersion, from: &parsedOptions)
    try commandLine.appendLast(.enforceExclusivityEQ, from: &parsedOptions)
    try commandLine.appendLast(.statsOutputDir, from: &parsedOptions)
    try commandLine.appendLast(.traceStatsEvents, from: &parsedOptions)
    try commandLine.appendLast(.profileStatsEvents, from: &parsedOptions)
    try commandLine.appendLast(.profileStatsEntities, from: &parsedOptions)
    try commandLine.appendLast(.solverShrinkUnsolvedThreshold, from: &parsedOptions)
    try commandLine.appendLast(in: .O, from: &parsedOptions)
    try commandLine.appendLast(.RemoveRuntimeAsserts, from: &parsedOptions)
    try commandLine.appendLast(.AssumeSingleThreaded, from: &parsedOptions)
    try commandLine.appendLast(.packageDescriptionVersion, from: &parsedOptions)
    try commandLine.appendLast(.serializeDiagnosticsPath, from: &parsedOptions)
    try commandLine.appendLast(.debugDiagnosticNames, from: &parsedOptions)
    try commandLine.appendLast(.scanDependencies, from: &parsedOptions)
    try commandLine.appendLast(.enableExperimentalConcisePoundFile, from: &parsedOptions)
    try commandLine.appendLast(.printEducationalNotes, from: &parsedOptions)
    try commandLine.appendLast(.diagnosticStyle, from: &parsedOptions)
    try commandLine.appendLast(.locale, from: &parsedOptions)
    try commandLine.appendLast(.localizationPath, from: &parsedOptions)
    try commandLine.appendLast(.requireExplicitAvailability, from: &parsedOptions)
    try commandLine.appendLast(.requireExplicitAvailabilityTarget, from: &parsedOptions)
    try commandLine.appendLast(.libraryLevel, from: &parsedOptions)
    try commandLine.appendLast(.lto, from: &parsedOptions)
    try commandLine.appendLast(.accessNotesPath, from: &parsedOptions)
    try commandLine.appendLast(.enableActorDataRaceChecks, .disableActorDataRaceChecks, from: &parsedOptions)
    try commandLine.appendAll(.D, from: &parsedOptions)
    try commandLine.appendAll(.debugPrefixMap, .coveragePrefixMap, .filePrefixMap, from: &parsedOptions)
    try commandLine.appendAllArguments(.Xfrontend, from: &parsedOptions)
    try commandLine.appendLast(.warnConcurrency, from: &parsedOptions)
    if isFrontendArgSupported(.enableExperimentalFeature) {
      try commandLine.appendAll(
        .enableExperimentalFeature, from: &parsedOptions)
    }
    if isFrontendArgSupported(.enableUpcomingFeature) {
      try commandLine.appendAll(
        .enableUpcomingFeature, from: &parsedOptions)
    }
    try commandLine.appendAll(.moduleAlias, from: &parsedOptions)
    if isFrontendArgSupported(.enableBareSlashRegex) {
      try commandLine.appendLast(.enableBareSlashRegex, from: &parsedOptions)
    }
    if isFrontendArgSupported(.strictConcurrency) {
      try commandLine.appendLast(.strictConcurrency, from: &parsedOptions)
    }

    // Expand the -experimental-hermetic-seal-at-link flag
    if parsedOptions.hasArgument(.experimentalHermeticSealAtLink) {
      commandLine.appendFlag("-enable-llvm-vfe")
      commandLine.appendFlag("-enable-llvm-wme")
      commandLine.appendFlag("-conditional-runtime-records")
      commandLine.appendFlag("-internalize-at-link")
    }

    // ABI descriptors are mostly for modules with -enable-library-evolution.
    // We should also be able to emit ABI descriptor for modules without evolution.
    // However, doing so leads us to deserialize more contents from binary modules,
    // exposing more deserialization issues as a result.
    if !parsedOptions.hasArgument(.enableLibraryEvolution) &&
        isFrontendArgSupported(.emptyAbiDescriptor) {
      commandLine.appendFlag(.emptyAbiDescriptor)
    }

    if isFrontendArgSupported(.emitMacroExpansionFiles) {
      try commandLine.appendLast(.emitMacroExpansionFiles, from: &parsedOptions)
    }

    if isFrontendArgSupported(.pluginPath) {
      try commandLine.appendAll(.pluginPath, from: &parsedOptions)

      let defaultPluginPath = try toolchain.executableDir.parentDirectory
        .appending(components: "lib", "swift", "host", "plugins")
      commandLine.appendFlag(.pluginPath)
      commandLine.appendPath(defaultPluginPath)

      let localPluginPath = try toolchain.executableDir.parentDirectory
        .appending(components: "local", "lib", "swift", "host", "plugins")
      commandLine.appendFlag(.pluginPath)
      commandLine.appendPath(localPluginPath)
    }

    if isFrontendArgSupported(.blockListFile) {
      try Driver.findBlocklists(RelativeTo: try toolchain.executableDir).forEach {
        commandLine.appendFlag(.blockListFile)
        commandLine.appendPath($0)
      }
    }

    // Pass down -user-module-version if we are working with a compiler that
    // supports it.
    if let ver = parsedOptions.getLastArgument(.userModuleVersion)?.asSingle,
       isFrontendArgSupported(.userModuleVersion) {
      commandLine.appendFlag(.userModuleVersion)
      commandLine.appendFlag(ver)
    }

    // Pass down -validate-clang-modules-once if we are working with a compiler that
    // supports it.
    if isFrontendArgSupported(.validateClangModulesOnce),
       isFrontendArgSupported(.clangBuildSessionFile) {
      try commandLine.appendLast(.validateClangModulesOnce, from: &parsedOptions)
      try commandLine.appendLast(.clangBuildSessionFile, from: &parsedOptions)
    }

    if isFrontendArgSupported(.enableBuiltinModule) {
      try commandLine.appendLast(.enableBuiltinModule, from: &parsedOptions)
    }

    if let workingDirectory = workingDirectory {
      // Add -Xcc -working-directory before any other -Xcc options to ensure it is
      // overridden by an explicit -Xcc -working-directory, although having a
      // different working directory is probably incorrect.
      commandLine.appendFlag(.Xcc)
      commandLine.appendFlag(.workingDirectory)
      commandLine.appendFlag(.Xcc)
      commandLine.appendPath(.absolute(workingDirectory))
    }

    // Resource directory.
    commandLine.appendFlag(.resourceDir)
    commandLine.appendPath(VirtualPath.lookup(frontendTargetInfo.runtimeResourcePath.path))

    if self.useStaticResourceDir {
      commandLine.appendFlag("-use-static-resource-dir")
    }

    // -g implies -enable-anonymous-context-mangled-names, because the extra
    // metadata aids debugging.
    if parsedOptions.getLast(in: .g) != nil {
      // But don't add the option in optimized builds: it would prevent dead code
      // stripping of unused metadata.
      let shouldSupportAnonymousContextMangledNames: Bool
      if let opt = parsedOptions.getLast(in: .O), opt.option != .Onone {
        shouldSupportAnonymousContextMangledNames = false
      } else {
        shouldSupportAnonymousContextMangledNames = true
      }

      if shouldSupportAnonymousContextMangledNames {
        commandLine.appendFlag(.enableAnonymousContextMangledNames)
      }

      // TODO: Should we support -fcoverage-compilation-dir?
      try commandLine.appendAll(.fileCompilationDir, from: &parsedOptions)
    }

    // Pass through any subsystem flags.
    try commandLine.appendAll(.Xllvm, from: &parsedOptions)
    try commandLine.appendAll(.Xcc, from: &parsedOptions)

    if let importedObjCHeader = importedObjCHeader,
        bridgingHeaderHandling != .ignored {
      commandLine.appendFlag(.importObjcHeader)
      if bridgingHeaderHandling == .precompiled,
          let pch = bridgingPrecompiledHeader {
        // For explicit module build, we directly pass the compiled pch as
        // `-import-objc-header`, rather than rely on swift-frontend to locate
        // the pch in the pchOutputDir and can start an implicit build in case
        // of a lookup failure.
        if parsedOptions.contains(.pchOutputDir) &&
           !parsedOptions.contains(.driverExplicitModuleBuild) {
          commandLine.appendPath(VirtualPath.lookup(importedObjCHeader))
          try commandLine.appendLast(.pchOutputDir, from: &parsedOptions)
          if !compilerMode.isSingleCompilation {
            commandLine.appendFlag(.pchDisableValidation)
          }
        } else {
          commandLine.appendPath(VirtualPath.lookup(pch))
        }
      } else {
        commandLine.appendPath(VirtualPath.lookup(importedObjCHeader))
      }
    }

    // Repl Jobs shouldn't include -module-name.
    if compilerMode != .repl && compilerMode != .intro {
      commandLine.appendFlags("-module-name", moduleOutputInfo.name)
    }

    if let packageName = packageName {
      commandLine.appendFlags("-package-name", packageName)
    }

    // Enable frontend Parseable-output, if needed.
    if parsedOptions.contains(.useFrontendParseableOutput) {
      commandLine.appendFlag("-frontend-parseable-output")
    }

    savedUnknownDriverFlagsForSwiftFrontend.forEach {
      commandLine.appendFlag($0)
    }

    try toolchain.addPlatformSpecificCommonFrontendOptions(commandLine: &commandLine,
                                                           inputs: &inputs,
                                                           frontendTargetInfo: frontendTargetInfo,
                                                           driver: &self)
  }

  mutating func addFrontendSupplementaryOutputArguments(commandLine: inout [Job.ArgTemplate],
                                                        primaryInputs: [TypedVirtualPath],
                                                        inputsGeneratingCodeCount: Int,
                                                        inputOutputMap: inout [TypedVirtualPath: [TypedVirtualPath]],
                                                        includeModuleTracePath: Bool,
                                                        indexFilePath: TypedVirtualPath?) throws -> [TypedVirtualPath] {
    var flaggedInputOutputPairs: [(flag: String, input: TypedVirtualPath?, output: TypedVirtualPath)] = []

    /// Add output of a particular type, if needed.
    func addOutputOfType(
      outputType: FileType,
      finalOutputPath: VirtualPath.Handle?,
      input: TypedVirtualPath?,
      flag: String
    ) throws {
      // If there is no final output, there's nothing to do.
      guard let finalOutputPath = finalOutputPath else { return }

      // If the whole of the compiler output is this type, there's nothing to
      // do.
      if outputType == compilerOutputType { return }

      // Compute the output path based on the input path (if there is one), or
      // use the final output.
      let outputPath: VirtualPath.Handle
      if let input = input {
        if let outputFileMapPath = try outputFileMap?.existingOutput(inputFile: input.fileHandle, outputType: outputType) {
          outputPath = outputFileMapPath
        } else if let output = inputOutputMap[input]?.first, output.file != .standardOutput, compilerOutputType != nil {
          // Alongside primary output
          outputPath = try output.file.replacingExtension(with: outputType).intern()
        } else {
          outputPath = VirtualPath.createUniqueTemporaryFile(RelativePath(input.file.basenameWithoutExt.appendingFileTypeExtension(outputType))).intern()
        }

        // Update the input-output file map.
        let output = TypedVirtualPath(file: outputPath, type: outputType)
        if inputOutputMap[input] != nil {
          inputOutputMap[input]!.append(output)
        } else {
          inputOutputMap[input] = [output]
        }
      } else {
        outputPath = finalOutputPath
      }

      flaggedInputOutputPairs.append((flag: flag, input: input, output: TypedVirtualPath(file: outputPath, type: outputType)))
    }

    /// Add all of the outputs needed for a given input.
    func addAllOutputsFor(input: TypedVirtualPath?) throws {
      if !emitModuleSeparately {
        // Generate the module files with the main job.
        try addOutputOfType(
          outputType: .swiftModule,
          finalOutputPath: moduleOutputInfo.output?.outputPath,
          input: input,
          flag: "-emit-module-path")
        try addOutputOfType(
          outputType: .swiftDocumentation,
          finalOutputPath: moduleDocOutputPath,
          input: input,
          flag: "-emit-module-doc-path")
        try addOutputOfType(
          outputType: .swiftSourceInfoFile,
          finalOutputPath: moduleSourceInfoPath,
          input: input,
          flag: "-emit-module-source-info-path")
      }

      try addOutputOfType(
        outputType: .dependencies,
        finalOutputPath: dependenciesFilePath,
        input: input,
        flag: "-emit-dependencies-path")

      try addOutputOfType(
        outputType: .swiftConstValues,
        finalOutputPath: constValuesFilePath,
        input: input,
        flag: "-emit-const-values-path")

      try addOutputOfType(
        outputType: .swiftDeps,
        finalOutputPath: referenceDependenciesPath,
        input: input,
        flag: "-emit-reference-dependencies-path")

      try addOutputOfType(
        outputType: self.optimizationRecordFileType ?? .yamlOptimizationRecord,
        finalOutputPath: optimizationRecordPath,
        input: input,
        flag: "-save-optimization-record-path")

      try addOutputOfType(
        outputType: .diagnostics,
        finalOutputPath: serializedDiagnosticsFilePath,
        input: input,
        flag: "-serialize-diagnostics-path")
    }

    if compilerMode.usesPrimaryFileInputs {
      for input in primaryInputs {
        try addAllOutputsFor(input: input)
      }
    } else {
      try addAllOutputsFor(input: nil)

      if !emitModuleSeparately {
        // Outputs that only make sense when the whole module is processed
        // together.
        try addOutputOfType(
          outputType: .objcHeader,
          finalOutputPath: objcGeneratedHeaderPath,
          input: nil,
          flag: "-emit-objc-header-path")

        try addOutputOfType(
          outputType: .swiftInterface,
          finalOutputPath: swiftInterfacePath,
          input: nil,
          flag: "-emit-module-interface-path")

        try addOutputOfType(
          outputType: .privateSwiftInterface,
          finalOutputPath: swiftPrivateInterfacePath,
          input: nil,
          flag: "-emit-private-module-interface-path")

        try addOutputOfType(
          outputType: .tbd,
          finalOutputPath: tbdPath,
          input: nil,
          flag: "-emit-tbd-path")

        if let abiDescriptorPath = abiDescriptorPath {
          try addOutputOfType(outputType: .jsonABIBaseline,
                          finalOutputPath: abiDescriptorPath.fileHandle,
                          input: nil,
                          flag: "-emit-abi-descriptor-path")
        }
      }
    }

    if parsedOptions.hasArgument(.updateCode) {
      guard compilerMode == .standardCompile else {
        diagnosticEngine.emit(.error_update_code_not_supported(in: compilerMode))
        throw ErrorDiagnostics.emitted
      }
      assert(primaryInputs.count == 1, "Standard compile job had more than one primary input")
      let input = primaryInputs[0]
      let remapOutputPath: VirtualPath
      if let outputFileMapPath = try outputFileMap?.existingOutput(inputFile: input.fileHandle, outputType: .remap) {
        remapOutputPath = VirtualPath.lookup(outputFileMapPath)
      } else if let output = inputOutputMap[input]?.first, output.file != .standardOutput {
        // Alongside primary output
        remapOutputPath = try output.file.replacingExtension(with: .remap)
      } else {
        remapOutputPath =
          VirtualPath.createUniqueTemporaryFile(RelativePath(input.file.basenameWithoutExt.appendingFileTypeExtension(.remap)))
      }

      flaggedInputOutputPairs.append((flag: "-emit-remap-file-path",
                                      input: input,
                                      output: TypedVirtualPath(file: remapOutputPath.intern(), type: .remap)))
    }

    if includeModuleTracePath, let tracePath = loadedModuleTracePath {
      flaggedInputOutputPairs.append((flag: "-emit-loaded-module-trace-path",
                                      input: nil,
                                      output: TypedVirtualPath(file: tracePath, type: .moduleTrace)))
    }

    if inputsGeneratingCodeCount * FileType.allCases.count > fileListThreshold {
      var entries = [VirtualPath.Handle: [FileType: VirtualPath.Handle]]()
      for input in primaryInputs {
        if let output = inputOutputMap[input]?.first {
          addEntry(&entries, input: input, output: output)
        } else {
          // Primary inputs are expected to appear in the output file map even
          // if they have no corresponding outputs.
          entries[input.fileHandle] = [:]
        }
      }

      if primaryInputs.isEmpty {
        // To match the legacy driver behavior, make sure we add the first input file
        // to the output file map if compiling without primary inputs (WMO), even
        // if there aren't any corresponding outputs.
        entries[inputFiles[0].fileHandle] = [:]
      }

      for flaggedPair in flaggedInputOutputPairs {
        addEntry(&entries, input: flaggedPair.input, output: flaggedPair.output)
      }
      // To match the legacy driver behavior, make sure we add an entry for the
      // file under indexing and the primary output file path.
      if let indexFilePath = indexFilePath, let idxOutput = inputOutputMap[indexFilePath]?.first {
        entries[indexFilePath.fileHandle] = [.indexData: idxOutput.fileHandle]
      }
      let outputFileMap = OutputFileMap(entries: entries)
      let fileList = VirtualPath.createUniqueFilelist(RelativePath("supplementaryOutputs"),
                                                      .outputFileMap(outputFileMap))
      commandLine.appendFlag(.supplementaryOutputFileMap)
      commandLine.appendPath(fileList)
    } else {
      for flaggedPair in flaggedInputOutputPairs {
        // Add the appropriate flag.
        commandLine.appendFlag(flaggedPair.flag)
        commandLine.appendPath(flaggedPair.output.file)
      }
    }

    return flaggedInputOutputPairs.map { $0.output }
  }

  func addEntry(_ entries: inout [VirtualPath.Handle: [FileType: VirtualPath.Handle]], input: TypedVirtualPath?, output: TypedVirtualPath) {
    let entryInput: VirtualPath.Handle
    if let input = input?.fileHandle, input != OutputFileMap.singleInputKey {
      entryInput = input
    } else {
      entryInput = inputFiles[0].fileHandle
    }
    entries[entryInput, default: [:]][output.type] = output.fileHandle
  }

  /// Adds all dependencies required for an explicit module build
  /// to inputs and command line arguments of a compile job.
  func addExplicitModuleBuildArguments(inputs: inout [TypedVirtualPath],
                                       commandLine: inout [Job.ArgTemplate]) throws {
    guard var dependencyPlanner = explicitDependencyBuildPlanner else {
      fatalError("No dependency planner in Explicit Module Build mode.")
    }
    try dependencyPlanner.resolveMainModuleDependencies(inputs: &inputs, commandLine: &commandLine)
  }

  /// Adds all dependencies required for an explicit module build of the bridging header
  /// to inputs and command line arguments of a compile job.
  func addExplicitPCHBuildArguments(inputs: inout [TypedVirtualPath],
                                    commandLine: inout [Job.ArgTemplate]) throws {
    guard var dependencyPlanner = explicitDependencyBuildPlanner else {
      fatalError("No dependency planner in Explicit Module Build mode.")
    }
    try dependencyPlanner.resolveBridgingHeaderDependencies(inputs: &inputs, commandLine: &commandLine)
  }

  /// In Explicit Module Build mode, distinguish between main module jobs and intermediate dependency build jobs,
  /// such as Swift modules built from .swiftmodule files and Clang PCMs.
  public func isExplicitMainModuleJob(job: Job) -> Bool {
    return job.moduleName == moduleOutputInfo.name
  }
}