Add swift crash producer support

When swift compiler crashed with swift caching enabled, create a crash
reproducer automatically.

Author: cachemeifyoucan

Sources/SwiftDriver/Driver/Driver.swift

@@ -23,6 +23,7 @@ import struct TSCBasic.AbsolutePath
 import struct TSCBasic.ByteString
 import struct TSCBasic.Diagnostic
 import struct TSCBasic.FileInfo
+import struct TSCBasic.ProcessResult
 import struct TSCBasic.RelativePath
 import struct TSCBasic.SHA256
 import var TSCBasic.localFileSystem
@@ -71,6 +72,7 @@ public struct Driver {
     case conditionalCompilationFlagIsNotValidIdentifier(String)
     case baselineGenerationRequiresTopLevelModule(String)
     case optionRequiresAnother(String, String)
+    case unableToCreateReproducer
     // Explicit Module Build Failures
     case malformedModuleDependency(String, String)
     case missingModuleDependency(String)
@@ -142,6 +144,8 @@ public struct Driver {
         return "generating a baseline with '\(arg)' is only supported with '-emit-module' or '-emit-module-path'"
       case .optionRequiresAnother(let first, let second):
         return "'\(first)' cannot be specified if '\(second)' is not present"
+      case .unableToCreateReproducer:
+        return "failed to create reproducer"
       }
     }
   }
@@ -962,7 +966,7 @@ public struct Driver {
                                                       negative: .disableIncrementalFileHashing,
                                                       default: false)
     self.recordedInputMetadata = .init(uniqueKeysWithValues:
-      Set(inputFiles).compactMap { inputFile -> (TypedVirtualPath, FileMetadata)? in 
+      Set(inputFiles).compactMap { inputFile -> (TypedVirtualPath, FileMetadata)? in
         guard let modTime = try? fileSystem.lastModificationTime(for: inputFile.file) else { return nil }
         if incrementalFileHashes {
             guard let data = try? fileSystem.readFileContents(inputFile.file)  else { return nil }
@@ -1957,7 +1961,8 @@ extension Driver {
       buildRecordInfo: buildRecordInfo,
       showJobLifecycle: showJobLifecycle,
       argsResolver: executor.resolver,
-      diagnosticEngine: diagnosticEngine)
+      diagnosticEngine: diagnosticEngine,
+      reproducerCallback: self.generateReproducer)
   }
 
   private mutating func performTheBuild(
@@ -4019,3 +4024,36 @@ extension Driver {
     return mapping
   }
 }
+
+// Generate reproducer.
+extension Driver {
+  func generateReproducer(_ job: Job, _ status: ProcessResult.ExitStatus) throws {
+    // If process is not terminated with certain error code, no need to create reproducer.
+#if os(Windows)
+    guard case .abnormal = status else {
+      return;
+    }
+#else
+    guard case .signalled = status else {
+      return;
+    }
+#endif
+    guard isFrontendArgSupported(.genReproducer), enableCaching, job.kind.supportCaching else {
+      return
+    }
+    // TODO: check flag is supported.
+    try withTemporaryDirectory(dir: fileSystem.tempDirectory, prefix: "swift-reproducer", removeTreeOnDeinit: false) { tempDir in
+      var reproJob = job
+      reproJob.commandLine.appendFlag(.genReproducer)
+      reproJob.commandLine.appendFlag(.genReproducerDir)
+      reproJob.commandLine.appendPath(tempDir)
+      reproJob.outputs.removeAll()
+      reproJob.outputCacheKeys.removeAll()
+      let result = try executor.execute(job: reproJob, forceResponseFiles: false, recordedInputModificationDates: [:])
+      guard case .terminated(let code) = result.exitStatus, code == 0 else {
+        throw Error.unableToCreateReproducer
+      }
+      diagnosticEngine.emit(.note_reproducer_created(tempDir.pathString))
+    }
+  }
+}

Sources/SwiftDriver/Driver/ToolExecutionDelegate.swift

@@ -30,6 +30,7 @@ import struct TSCBasic.Diagnostic
 import struct TSCBasic.ProcessResult
 import var TSCBasic.stderrStream
 import var TSCBasic.stdoutStream
+import class TSCBasic.Process
 
 /// Delegate for printing execution information on the command-line.
 @_spi(Testing) public final class ToolExecutionDelegate: JobExecutionDelegate {
@@ -49,6 +50,8 @@ import var TSCBasic.stdoutStream
     case silent
   }
 
+  public typealias ReproducerCallback = (Job, ProcessResult.ExitStatus) throws -> Void
+
   public let mode: Mode
   public let buildRecordInfo: BuildRecordInfo?
   public let showJobLifecycle: Bool
@@ -58,18 +61,21 @@ import var TSCBasic.stdoutStream
   private var nextBatchQuasiPID: Int
   private let argsResolver: ArgsResolver
   private var batchJobInputQuasiPIDMap = TwoLevelMap<Job, TypedVirtualPath, Int>()
+  private let reproducerCallback: ReproducerCallback?
 
   @_spi(Testing) public init(mode: ToolExecutionDelegate.Mode,
                              buildRecordInfo: BuildRecordInfo?,
                              showJobLifecycle: Bool,
                              argsResolver: ArgsResolver,
-                             diagnosticEngine: DiagnosticsEngine) {
+                             diagnosticEngine: DiagnosticsEngine,
+                             reproducerCallback: ReproducerCallback? = nil) {
     self.mode = mode
     self.buildRecordInfo = buildRecordInfo
     self.showJobLifecycle = showJobLifecycle
     self.diagnosticEngine = diagnosticEngine
     self.argsResolver = argsResolver
     self.nextBatchQuasiPID = ToolExecutionDelegate.QUASI_PID_START
+    self.reproducerCallback = reproducerCallback
   }
 
   public func jobStarted(job: Job, arguments: [String], pid: Int) {
@@ -107,6 +113,14 @@ import var TSCBasic.stdoutStream
     }
 #endif
 
+    if let reproducerCallback = reproducerCallback {
+      do {
+        try reproducerCallback(job, result.exitStatus)
+      } catch {
+        diagnosticEngine.emit(.error_failed_to_create_reproducer)
+      }
+    }
+
     switch mode {
     case .silent:
       break

Sources/SwiftDriver/Utilities/Diagnostics.swift

@@ -182,4 +182,12 @@ extension Diagnostic.Message {
   static var error_no_objc_interop_embedded: Diagnostic.Message {
     .error("Objective-C interop cannot be enabled with embedded Swift.")
   }
+
+  static var error_failed_to_create_reproducer: Diagnostic.Message {
+    .error("failed to create crash reproducer")
+  }
+
+  static func note_reproducer_created(_ path: String) -> Diagnostic.Message {
+    .note("crash reproducer is created at: \(path)")
+  }
 }

Sources/SwiftOptions/Options.swift

@@ -586,6 +586,8 @@ extension Option {
   public static let F: Option = Option("-F", .joinedOrSeparate, attributes: [.frontend, .synthesizeInterface, .argumentIsPath], helpText: "Add directory to framework search path")
   public static let gccToolchain: Option = Option("-gcc-toolchain", .separate, attributes: [.helpHidden, .argumentIsPath], metaVar: "<path>", helpText: "Specify a directory where the clang importer and clang linker can find headers and libraries")
   public static let gdwarfTypes: Option = Option("-gdwarf-types", .flag, attributes: [.frontend], helpText: "Emit full DWARF type info.", group: .g)
+  public static let genReproducerDir: Option = Option("-gen-reproducer-dir", .separate, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Path to directory where reproducers write to.")
+  public static let genReproducer: Option = Option("-gen-reproducer", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Generate a reproducer for current compilation.")
   public static let generateEmptyBaseline: Option = Option("-generate-empty-baseline", .flag, attributes: [.noDriver], helpText: "Generate an empty baseline")
   public static let generateEmptyBaseline_: Option = Option("--generate-empty-baseline", .flag, alias: Option.generateEmptyBaseline, attributes: [.noDriver], helpText: "Generate an empty baseline")
   public static let generateMigrationScript: Option = Option("-generate-migration-script", .flag, attributes: [.noDriver], helpText: "Compare SDK content in JSON file and generate migration script")
@@ -1553,6 +1555,8 @@ extension Option {
       Option.F,
       Option.gccToolchain,
       Option.gdwarfTypes,
+      Option.genReproducerDir,
+      Option.genReproducer,
       Option.generateEmptyBaseline,
       Option.generateEmptyBaseline_,
       Option.generateMigrationScript,