Infer object format when it can't be determined from a triple's successfully parsed environment

Sources/SwiftDriver/CMakeLists.txt

@@ -49,6 +49,7 @@ add_library(SwiftDriver
   Jobs/Job.swift
   Jobs/LinkJob.swift
   Jobs/MergeModuleJob.swift
+  Jobs/ModuleWrapJob.swift
   Jobs/Planning.swift
   Jobs/PrintTargetInfoJob.swift
   Jobs/ReplJob.swift

Sources/SwiftDriver/Jobs/Job.swift

@@ -23,6 +23,7 @@ public struct Job: Codable, Equatable, Hashable {
     case autolinkExtract = "autolink-extract"
     case emitModule = "emit-module"
     case generatePCH = "generate-pch"
+    case moduleWrap = "module-wrap"
 
     /// Generate a compiled Clang module.
     case generatePCM = "generate-pcm"
@@ -145,6 +146,9 @@ extension Job : CustomStringConvertible {
     case .generatePCH:
         return "Compiling bridging header \(displayInputs.first?.file.basename ?? "")"
 
+    case .moduleWrap:
+      return "Wrapping Swift module \(moduleName)"
+
     case .generatePCM:
         return "Compiling Clang module \(displayInputs.first?.file.basename  ?? "")"
 
@@ -184,7 +188,7 @@ extension Job.Kind {
         .versionRequest, .scanDependencies:
         return true
 
-    case .autolinkExtract, .generateDSYM, .help, .link, .verifyDebugInfo:
+    case .autolinkExtract, .generateDSYM, .help, .link, .verifyDebugInfo, .moduleWrap:
         return false
     }
   }
@@ -197,7 +201,8 @@ extension Job.Kind {
     case .backend, .mergeModule, .emitModule, .generatePCH,
          .generatePCM, .interpret, .repl, .printTargetInfo,
          .versionRequest, .autolinkExtract, .generateDSYM,
-         .help, .link, .verifyDebugInfo, .scanDependencies:
+         .help, .link, .verifyDebugInfo, .scanDependencies,
+         .moduleWrap:
       return false
     }
   }

Sources/SwiftDriver/Jobs/ModuleWrapJob.swift

@@ -0,0 +1,39 @@
+//===--------------- ModuleWrapJob.swift - Swift Module Wrapping ----------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2020 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
+//
+//===----------------------------------------------------------------------===//
+
+extension Driver {
+  mutating func moduleWrapJob(moduleInput: TypedVirtualPath) throws -> Job {
+    var commandLine: [Job.ArgTemplate] = swiftCompilerPrefixArgs.map { Job.ArgTemplate.flag($0) }
+
+    commandLine.appendFlags("-modulewrap")
+
+    // Add the input.
+    commandLine.append(.path(moduleInput.file))
+    assert(compilerOutputType == .object, "-modulewrap mode only produces object files")
+
+    commandLine.appendFlags("-target", targetTriple.triple)
+
+    let outputPath = try moduleInput.file.replacingExtension(with: .object)
+    commandLine.appendFlag("-o")
+    commandLine.appendPath(outputPath)
+
+    return Job(
+      moduleName: moduleOutputInfo.name,
+      kind: .moduleWrap,
+      tool: .absolute(try toolchain.getToolPath(.swiftCompiler)),
+      commandLine: commandLine,
+      inputs: [moduleInput],
+      outputs: [.init(file: outputPath, type: .object)],
+      supportsResponseFiles: true
+    )
+  }
+}

Sources/SwiftDriver/Jobs/Planning.swift

@@ -188,8 +188,10 @@ extension Driver {
     jobs.append(contentsOf: backendJobs)
 
     // Plan the merge-module job, if there are module inputs.
+    var mergeJob: Job?
     if moduleOutputInfo.output != nil && !moduleInputs.isEmpty && compilerMode.usesPrimaryFileInputs {
-      jobs.append(try mergeModuleJob(inputs: moduleInputs))
+      mergeJob = try mergeModuleJob(inputs: moduleInputs)
+      jobs.append(mergeJob!)
     }
 
     // If we need to autolink-extract, do so.
@@ -199,6 +201,20 @@ extension Driver {
       jobs.append(autolinkExtractJob)
     }
 
+    if let mergeJob = mergeJob, debugInfo.level == .astTypes {
+      if targetTriple.objectFormat != .macho {
+        // Module wrapping is required.
+        let mergeModuleOutputs = mergeJob.outputs.filter { $0.type == .swiftModule }
+        assert(mergeModuleOutputs.count == 1,
+               "Merge module job should only have one swiftmodule output")
+        let wrapJob = try moduleWrapJob(moduleInput: mergeModuleOutputs[0])
+        linkerInputs.append(contentsOf: wrapJob.outputs)
+        jobs.append(wrapJob)
+      } else {
+        linkerInputs.append(contentsOf: mergeJob.outputs)
+      }
+    }
+
     // If we should link, do so.
     var link: Job?
     if linkerOutputType != nil && !linkerInputs.isEmpty {

Sources/SwiftDriver/Utilities/Triple.swift

@@ -167,6 +167,8 @@ public struct Triple {
     if let parsedEnv = parsedEnv {
       self.environment = parsedEnv.value.environment
       self.objectFormat = parsedEnv.value.objectFormat
+        ?? ObjectFormat.infer(arch: parsedArch?.value.arch,
+                              os: parsedOS?.value)
     }
     else {
       self.environment = Environment.infer(archName: parsedArch?.substring)

Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift

@@ -322,6 +322,11 @@ final class ExplicitModuleBuildTests: XCTestCase {
           case .relative(RelativePath("main")):
             XCTAssertTrue(driver.isExplicitMainModuleJob(job: job))
             XCTAssertEqual(job.kind, .link)
+
+          case .temporary(RelativePath("main.autolink")):
+            XCTAssertTrue(driver.isExplicitMainModuleJob(job: job))
+            XCTAssertEqual(job.kind, .autolinkExtract)
+
           default:
             XCTFail("Unexpected module dependency build job output: \(job.outputs[0].file)")
         }