PrebuiltModuleGen: generate per-interface log files

This is the behavior of swift_build_sdk_interfaces.py and we should do
the same in the new implementation.

Author: nkcsgexi

Sources/SwiftDriver/Jobs/PrebuiltModulesJob.swift

@@ -24,33 +24,40 @@ public class PrebuitModuleGenerationDelegate: JobExecutionDelegate {
   let diagnosticsEngine: DiagnosticsEngine
   let verbose: Bool
   var failingCriticalOutputs: Set<VirtualPath>
-  public init(_ jobs: [Job], _ diagnosticsEngine: DiagnosticsEngine, _ verbose: Bool) {
+  let logPath: AbsolutePath?
+  public init(_ jobs: [Job], _ diagnosticsEngine: DiagnosticsEngine, _ verbose: Bool, logPath: AbsolutePath?) {
     self.diagnosticsEngine = diagnosticsEngine
     self.verbose = verbose
     self.failingCriticalOutputs = Set<VirtualPath>(jobs.compactMap(PrebuitModuleGenerationDelegate.getCriticalOutput))
+    self.logPath = logPath
   }
 
   /// Dangling jobs are macabi-only modules. We should run those jobs if foundation
   /// is built successfully for macabi.
   public var shouldRunDanglingJobs: Bool {
     return !failingCriticalOutputs.contains(where: isIosMac)
   }
-  func printJobInfo(_ job: Job, _ start: Bool) {
-    guard verbose else {
-      return
-    }
+
+  func getInputInterfacePath(_ job: Job) -> AbsolutePath {
     for arg in job.commandLine {
       if case .path(let p) = arg {
         if p.extension == "swiftinterface" {
-          Driver.stdErrQueue.sync {
-            stderrStream <<< (start ? "started: " : "finished: ")
-            stderrStream <<< p.absolutePath!.pathString <<< "\n"
-            stderrStream.flush()
-          }
-          return
+          return p.absolutePath!
         }
       }
     }
+    fatalError()
+  }
+
+  func printJobInfo(_ job: Job, _ start: Bool) {
+    guard verbose else {
+      return
+    }
+    Driver.stdErrQueue.sync {
+      stderrStream <<< (start ? "started: " : "finished: ")
+      stderrStream <<< getInputInterfacePath(job).pathString <<< "\n"
+      stderrStream.flush()
+    }
   }
 
   static func getCriticalOutput(_ job: Job) -> VirtualPath? {
@@ -66,6 +73,24 @@ public class PrebuitModuleGenerationDelegate: JobExecutionDelegate {
     return !failingCriticalOutputs.isEmpty
   }
 
+  fileprivate func logOutput(_ job: Job, _ result: ProcessResult, _ stdout: Bool) throws {
+    guard let logPath = logPath else {
+      return
+    }
+    let content = stdout ? try result.utf8Output() : try result.utf8stderrOutput()
+    guard !content.isEmpty else {
+      return
+    }
+    if !localFileSystem.exists(logPath) {
+      try localFileSystem.createDirectory(logPath, recursive: true)
+    }
+    let interfaceBase = getInputInterfacePath(job).basenameWithoutExt
+    let fileName = "\(job.moduleName)-\(interfaceBase)-\(stdout ? "out" : "err").txt"
+    try localFileSystem.writeFileContents(logPath.appending(component: fileName)) {
+      $0 <<< content
+    }
+  }
+
   public func jobFinished(job: Job, result: ProcessResult, pid: Int) {
     switch result.exitStatus {
     case .terminated(code: let code):
@@ -86,6 +111,15 @@ public class PrebuitModuleGenerationDelegate: JobExecutionDelegate {
       diagnosticsEngine.emit(.remark("\(job.moduleName) interrupted"))
 #endif
     }
+    do {
+      try logOutput(job, result, true)
+      try logOutput(job, result, false)
+    } catch {
+      Driver.stdErrQueue.sync {
+        stderrStream <<< "Failed to generate log file"
+        stderrStream.flush()
+      }
+    }
   }
 
   public func jobSkipped(job: Job) {

Sources/swift-build-sdk-interfaces/main.swift

@@ -137,7 +137,7 @@ do {
     if skipExecution {
       exit(0)
     }
-    let delegate = PrebuitModuleGenerationDelegate(jobs, diagnosticsEngine, verbose)
+    let delegate = PrebuitModuleGenerationDelegate(jobs, diagnosticsEngine, verbose, logPath: try getArgumentAsPath("-log-path"))
     do {
       try executor.execute(workload: DriverExecutorWorkload.init(jobs, nil, continueBuildingAfterErrors: true),
                            delegate: delegate, numParallelJobs: 128)