We need to ensure that we terminate (SIGINT) the running compiler processes without emitting an error that those processes got terminated, and allow the driver to continue execution so that it is able to emit parseable-output which communicates that the terminated compiler jobs were interrupted.

Resolves rdar://74527749

Author: artemcm

Sources/SwiftDriverExecution/MultiJobExecutor.swift

@@ -539,7 +539,11 @@ class ExecuteJobRule: LLBuildRule {
           }
 #if !os(Windows)
         case let .signalled(signal):
-          context.diagnosticsEngine.emit(.error_command_signalled(kind: job.kind, signal: signal))
+          // An interrupt of an individual compiler job means it was deliberatly cancelled,
+          // most likely by the driver itself. This does not constitute an error.
+          if signal != SIGINT {
+            context.diagnosticsEngine.emit(.error_command_signalled(kind: job.kind, signal: signal))
+          }
 #endif
         }
       }

Sources/swift-driver/main.swift

@@ -18,15 +18,22 @@ import TSCUtility
 
 var intHandler: InterruptHandler?
 let diagnosticsEngine = DiagnosticsEngine(handlers: [Driver.stderrDiagnosticsHandler])
+var driverInterrupted = false
+func getExitCode(_ code: Int32) -> Int32 {
+  if driverInterrupted {
+    return (SIGINT | 0x80)
+  }
+  return code
+}
 
 do {
+
   let processSet = ProcessSet()
   intHandler = try InterruptHandler {
-    // Ignore the interruption signal.
-    // The underlying swift compiler isn't ready to be safely interrupted yet and
-    // interrupting them may cause red-herring build failures that may pollute the build
-    // log.
-    diagnosticsEngine.emit(.remark("Compilation process interrupted"))
+    // Terminate running compiler jobs and let the driver exit gracefully, remembering
+    // to return a corresponding exit code when done.
+    processSet.terminate()
+    driverInterrupted = true
   }
 
   if ProcessEnv.vars["SWIFT_ENABLE_EXPLICIT_MODULE"] != nil {
@@ -57,6 +64,7 @@ do {
                           diagnosticsEngine: diagnosticsEngine,
                           executor: executor,
                           integratedDriver: false)
+  
   // FIXME: The following check should be at the end of Driver.init, but current
   // usage of the DiagnosticVerifier in tests makes this difficult.
   guard !driver.diagnosticEngine.hasErrors else { throw Diagnostics.fatalError }
@@ -65,14 +73,15 @@ do {
   try driver.run(jobs: jobs)
 
   if driver.diagnosticEngine.hasErrors {
-    exit(EXIT_FAILURE)
+    exit(getExitCode(EXIT_FAILURE))
   }
+  exit(getExitCode(0))
 } catch Diagnostics.fatalError {
-  exit(EXIT_FAILURE)
+  exit(getExitCode(EXIT_FAILURE))
 } catch let diagnosticData as DiagnosticData {
   diagnosticsEngine.emit(.error(diagnosticData))
-  exit(EXIT_FAILURE)
+  exit(getExitCode(EXIT_FAILURE))
 } catch {
   print("error: \(error)")
-  exit(EXIT_FAILURE)
+  exit(getExitCode(EXIT_FAILURE))
 }