[Swift] Add crash reproducer support (#686)

Add support for swift crash reproducer so a crash reproducer is created
if supported when a swift compiler crash happened.

Author: cachemeifyoucan

Sources/SWBCore/LibSwiftDriver/PlannedBuild.swift

@@ -529,6 +529,16 @@ extension LibSwiftDriver {
             }
         }
 
+        public func getCrashReproducerCommand(for job: PlannedSwiftDriverJob, output dir: Path) async throws -> [String]? {
+            try await dispatchQueue.sync {
+                let driverJob = try self.driverJob(for: job)
+                guard let reproJob = self.jobExecutionDelegate?.getReproducerJob(job: driverJob, output: try VirtualPath(path: dir.str)) else {
+                  return nil
+                }
+                return try self.argsResolver.resolveArgumentList(for: reproJob, useResponseFiles: .heuristic)
+            }
+        }
+
         public func getDiscoveredJobsAfterFinishing(job: PlannedSwiftDriverJob) throws -> [PlannedSwiftDriverJob] {
 
             dispatchQueue.blocking_sync {

Sources/SWBTaskExecution/TaskActions/SwiftDriverJobTaskAction.swift

@@ -420,6 +420,7 @@ public final class SwiftDriverJobTaskAction: TaskAction, BuildValueValidatingTas
                 private var pid = llbuild_pid_t.invalid
 
                 var executionError: String?
+                var wasSignaled: Bool = false
                 private var processStarted = false
                 private var _commandResult: CommandResult?
                 var commandResult: CommandResult? {
@@ -469,10 +470,15 @@ public final class SwiftDriverJobTaskAction: TaskAction, BuildValueValidatingTas
                 }
 
                 func processFinished(result: CommandExtendedResult) {
+                    if wasSignaled {
+                        // If the process was already signaled, this might be in a reproducer creation. No need to update finish status.
+                        return
+                    }
                     guard let status = Processes.ExitStatus.init(rawValue: result.exitStatus) else {
                         // nil means the job is stopped or continued. It should not call finished.
                         return
                     }
+                    wasSignaled = status.wasSignaled
                     // This may be updated by commandStarted in the case of certain failures,
                     // so only update the exit status in output delegate if it is nil.
                     if outputDelegate.result == nil {
@@ -526,6 +532,21 @@ public final class SwiftDriverJobTaskAction: TaskAction, BuildValueValidatingTas
 
             try await spawn(commandLine: options.commandLine, environment: environment, workingDirectory: task.workingDirectory, dynamicExecutionDelegate: dynamicExecutionDelegate, clientDelegate: clientDelegate, processDelegate: delegate)
 
+            // Generate crash reproducoer.
+            if delegate.wasSignaled {
+                // The output directory for crash reproducer is:
+                // * Specified by environment
+                // * Primary output path directory
+                // * Temp directory
+                let reproDir = environment["SWIFT_CRASH_DIAGNOSTICS_DIR"].map(Path.init) ?? driverJob.driverJob.outputs.first?.dirname
+                try await withTemporaryDirectory(dir: reproDir, prefix: "swift-crash-reproducer", removeTreeOnDeinit: false) { dir in
+                    if let reproCommand = try await plannedBuild?.getCrashReproducerCommand(for: driverJob, output: dir) {
+                        try await spawn(commandLine: reproCommand, environment: environment, workingDirectory: task.workingDirectory, dynamicExecutionDelegate: dynamicExecutionDelegate, clientDelegate: clientDelegate, processDelegate: delegate)
+                        outputDelegate.note("Crash reproducer created in \(dir.str)")
+                    }
+                }
+            }
+
             if let error = delegate.executionError {
                 outputDelegate.error(error)
                 return .failed