Code gen error handling: fail fast on throwable and print stack trace

src/compiler/scala/tools/nsc/backend/jvm/CodeGen.scala

@@ -15,6 +15,7 @@ package backend.jvm
 
 import scala.collection.mutable.ListBuffer
 import scala.tools.asm.tree.ClassNode
+import scala.tools.nsc.util.stackTraceString
 
 abstract class CodeGen[G <: Global](val global: G) extends PerRunInit {
   val bTypes: BTypesFromSymbols[global.type]
@@ -34,24 +35,25 @@ abstract class CodeGen[G <: Global](val global: G) extends PerRunInit {
     val generatedClasses = ListBuffer.empty[GeneratedClass]
 
     def genClassDef(cd: ClassDef): Unit = try {
-      val sym = cd.symbol
-      val position = sym.pos
-      val fullSymbolName = sym.javaClassName
-      val mainClassNode = genClass(cd, unit)
-      generatedClasses += GeneratedClass(mainClassNode, fullSymbolName, position, isArtifact = false)
-      if (bTypes.isTopLevelModuleClass(sym)) {
-        if (sym.companionClass == NoSymbol) {
-          val mirrorClassNode = genMirrorClass(sym, unit)
-          generatedClasses += GeneratedClass(mirrorClassNode, fullSymbolName, position, isArtifact = true)
+      if (!frontendAccess.directBackendReporting.hasErrors) {
+        val sym            = cd.symbol
+        val position       = sym.pos
+        val fullSymbolName = sym.javaClassName
+        val mainClassNode  = genClass(cd, unit)
+        generatedClasses += GeneratedClass(mainClassNode, fullSymbolName, position, isArtifact = false)
+        if (bTypes.isTopLevelModuleClass(sym)) {
+          if (sym.companionClass == NoSymbol) {
+            val mirrorClassNode = genMirrorClass(sym, unit)
+            generatedClasses += GeneratedClass(mirrorClassNode, fullSymbolName, position, isArtifact = true)
+          }
+          else
+            log(s"No mirror class for module with linked class: ${sym.fullName}")
         }
-        else
-          log(s"No mirror class for module with linked class: ${sym.fullName}")
       }
     } catch {
       case ex: InterruptedException => throw ex
       case ex: Throwable =>
-        if (settings.debug) ex.printStackTrace()
-        globalError(s"Error while emitting ${unit.source}\n${ex.getMessage}")
+        globalError(cd.pos, s"Error while emitting ${unit.source}\n${stackTraceString(ex)}")
     }
 
     def genClassDefs(tree: Tree): Unit = tree match {

src/compiler/scala/tools/nsc/backend/jvm/GeneratedClassHandler.scala

@@ -121,8 +121,10 @@ private[jvm] object GeneratedClassHandler {
         frontendAccess.withThreadLocalReporter(unitInPostProcess.bufferedReporting) {
           // we 'take' classes to reduce the memory pressure
           // as soon as the class is consumed and written, we release its data
-          unitInPostProcess.takeClasses() foreach {
-            postProcessor.sendToDisk(_, unitInPostProcess.sourceFile)
+          unitInPostProcess.takeClasses() foreach { cls =>
+            if (!frontendAccess.directBackendReporting.hasErrors) {
+              postProcessor.sendToDisk(cls, unitInPostProcess.sourceFile)
+            }
           }
         }
       }

src/compiler/scala/tools/nsc/backend/jvm/PostProcessor.scala

@@ -14,12 +14,12 @@ package scala.tools.nsc
 package backend.jvm
 
 import java.util.concurrent.ConcurrentHashMap
-
 import scala.collection.mutable
-import scala.reflect.internal.util.{NoPosition, Position, StringContextStripMarginOps}
+import scala.reflect.internal.util.{Position, StringContextStripMarginOps}
 import scala.reflect.io.AbstractFile
 import scala.tools.asm.ClassWriter
 import scala.tools.asm.tree.ClassNode
+import scala.tools.nsc
 import scala.tools.nsc.backend.jvm.analysis.BackendUtils
 import scala.tools.nsc.backend.jvm.opt._
 
@@ -74,9 +74,7 @@ abstract class PostProcessor extends PerRunInit {
     } catch {
       case ex: InterruptedException => throw ex
       case ex: Throwable =>
-        // TODO fail fast rather than continuing to write the rest of the class files?
-        if (frontendAccess.compilerSettings.debug) ex.printStackTrace()
-        backendReporting.error(NoPosition, s"Error while emitting $internalName\n${ex.getMessage}")
+        backendReporting.error(clazz.position, s"Error while emitting $internalName\n${nsc.util.stackTraceString(ex)}")
         null
     }
 

src/compiler/scala/tools/nsc/backend/jvm/PostProcessorFrontendAccess.scala

@@ -108,6 +108,7 @@ object PostProcessorFrontendAccess {
     def warning(pos: Position, message: String): Unit
     def inform(message: String): Unit
     def log(message: String): Unit
+    def hasErrors: Boolean
   }
 
   final class BufferingBackendReporting extends BackendReporting {
@@ -132,6 +133,10 @@ object PostProcessorFrontendAccess {
     def log(message: String): Unit =
       this.synchronized(bufferedReports ::= new ReportLog(message))
 
+    def hasErrors: Boolean = {
+      this.synchronized(bufferedReports.nonEmpty)
+    }
+
     def relayReports(toReporting: BackendReporting): Unit = this.synchronized {
       if (bufferedReports.nonEmpty) {
         bufferedReports.reverse.foreach(_.relay(toReporting))
@@ -262,6 +267,8 @@ object PostProcessorFrontendAccess {
       def log(message: String): Unit = frontendSynch {
         global.log(message)
       }
+
+      def hasErrors: Boolean = global.reporter.hasErrors
     }
     def unsafeStatistics: Statistics with BackendStats = global.statistics
 

test/files/run/large_class.check

@@ -1,2 +1,2 @@
-error: Error while emitting BigEnoughToFail
-Class too large: BigEnoughToFail
+newSource1.scala:1: error: Error while emitting BigEnoughToFail
+scala.tools.asm.ClassTooLargeException: Class too large: BigEnoughToFail

test/files/run/large_class.scala

@@ -1,3 +1,4 @@
+import java.io.{ByteArrayOutputStream, PrintWriter}
 import scala.tools.partest._
 
 // a cold run of partest takes about 15s for this test on my laptop
@@ -19,8 +20,11 @@ object Test extends DirectTest {
       |}""".stripMargin.trim
 
   override def show(): Unit = {
-    Console.withErr(System.out) {
+    val baos = new ByteArrayOutputStream()
+    Console.withErr(baos) {
       compile()
     }
+    val out = baos.toString()
+    println(out.linesIterator.take(2).mkString("\n"))
   }
 }

test/files/run/large_code.check

@@ -1,2 +1,2 @@
-error: Error while emitting BigEnoughToFail
-Method too large: BigEnoughToFail.tooLong ()V
+newSource1.scala:1: error: Error while emitting BigEnoughToFail
+scala.tools.asm.MethodTooLargeException: Method too large: BigEnoughToFail.tooLong ()V

test/files/run/large_code.scala

@@ -1,3 +1,4 @@
+import java.io.ByteArrayOutputStream
 import scala.tools.partest._
 
 // a cold run of partest takes about 15s for this test on my laptop
@@ -16,8 +17,11 @@ object Test extends DirectTest {
       |}""".stripMargin.trim
 
   override def show(): Unit = {
-    Console.withErr(System.out) {
+    val baos = new ByteArrayOutputStream()
+    Console.withErr(baos) {
       compile()
     }
+    val out = baos.toString()
+    println(out.linesIterator.take(2).mkString("\n"))
   }
 }