Merge pull request #2824 from qerub/ticket/7740

SI-7740 Trim stack trace before printing in REPL

4 files changed, 56 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/util/package.scala b/src/compiler/scala/tools/nsc/util/package.scala
index 752aac5c8c..ea3c9d8dde 100644
--- a/src/compiler/scala/tools/nsc/util/package.scala
+++ b/src/compiler/scala/tools/nsc/util/package.scala
@@ -8,6 +8,7 @@ package tools
 package nsc
 
 import java.io.{ OutputStream, PrintStream, ByteArrayOutputStream, PrintWriter, StringWriter }
+import scala.compat.Platform.EOL
 
 package object util {
 
@@ -78,6 +79,14 @@ package object util {
     s"$clazz$msg @ $frame"
   }
 
+  def stackTracePrefixString(ex: Throwable)(p: StackTraceElement => Boolean): String = {
+    val frames = ex.getStackTrace takeWhile p map ("  at " + _)
+    val msg    = ex.getMessage match { case null => "" ; case s => s": $s" }
+    val clazz  = ex.getClass.getName
+
+    s"$clazz$msg" +: frames mkString EOL
+  }
+
   lazy val trace = new SimpleTracer(System.out)
 
   @deprecated("Moved to scala.reflect.internal.util.StringOps", "2.10.0")
diff --git a/src/repl/scala/tools/nsc/interpreter/IMain.scala b/src/repl/scala/tools/nsc/interpreter/IMain.scala
index 1723344306..9596a360a9 100644
--- a/src/repl/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/repl/scala/tools/nsc/interpreter/IMain.scala
@@ -7,6 +7,8 @@ package scala
 package tools.nsc
 package interpreter
 
+import PartialFunction.cond
+
 import scala.language.implicitConversions
 
 import scala.collection.mutable
@@ -20,7 +22,7 @@ import scala.reflect.internal.util.{ BatchSourceFile, SourceFile }
 import scala.tools.util.PathResolver
 import scala.tools.nsc.io.AbstractFile
 import scala.tools.nsc.typechecker.{ TypeStrings, StructuredTypeStrings }
-import scala.tools.nsc.util.{ ScalaClassLoader, stringFromWriter }
+import scala.tools.nsc.util.{ ScalaClassLoader, stringFromWriter, stackTracePrefixString }
 import scala.tools.nsc.util.Exceptional.unwrap
 
 import javax.script.{AbstractScriptEngine, Bindings, ScriptContext, ScriptEngine, ScriptEngineFactory, ScriptException, CompiledScript, Compilable}
@@ -718,10 +720,18 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
         throw t
 
       val unwrapped = unwrap(t)
+
+      // Example input: $line3.$read$$iw$$iw$
+      val classNameRegex = (naming.lineRegex + ".*").r
+      def isWrapperInit(x: StackTraceElement) = cond(x.getClassName) {
+        case classNameRegex() if x.getMethodName == nme.CONSTRUCTOR.decoded => true
+      }
+      val stackTrace = util.stackTracePrefixString(unwrapped)(!isWrapperInit(_))
+
       withLastExceptionLock[String]({
         directBind[Throwable]("lastException", unwrapped)(StdReplTags.tagOfThrowable, classTag[Throwable])
-        util.stackTraceString(unwrapped)
-      }, util.stackTraceString(unwrapped))
+        stackTrace
+      }, stackTrace)
     }
 
     // TODO: split it out into a package object and a regular
diff --git a/src/repl/scala/tools/nsc/interpreter/Naming.scala b/src/repl/scala/tools/nsc/interpreter/Naming.scala
index 7f577b3a8b..cf38a2ae3a 100644
--- a/src/repl/scala/tools/nsc/interpreter/Naming.scala
+++ b/src/repl/scala/tools/nsc/interpreter/Naming.scala
@@ -40,7 +40,7 @@ trait Naming {
   //   $line3.$read$$iw$$iw$Bippy@4a6a00ca
 
   private def noMeta(s: String) = "\\Q" + s + "\\E"
-  private lazy val lineRegex = {
+  lazy val lineRegex = {
     val sn = sessionNames
     val members = List(sn.read, sn.eval, sn.print) map noMeta mkString ("(?:", "|", ")")
     debugging("lineRegex")(noMeta(sn.line) + """\d+[./]""" + members + """[$.]""")
diff --git a/test/files/run/repl-trim-stack-trace.scala b/test/files/run/repl-trim-stack-trace.scala
new file mode 100644
index 0000000000..bbf46f2f19
--- /dev/null
+++ b/test/files/run/repl-trim-stack-trace.scala
@@ -0,0 +1,33 @@
+
+import scala.tools.partest.SessionTest
+
+// SI-7740
+object Test extends SessionTest {
+  def session =
+"""Type in expressions to have them evaluated.
+Type :help for more information.
+
+scala> def f = throw new Exception("Uh-oh")
+f: Nothing
+
+scala> f
+java.lang.Exception: Uh-oh
+  at .f(<console>:7)
+
+scala> def f = throw new Exception("")
+f: Nothing
+
+scala> f
+java.lang.Exception: 
+  at .f(<console>:7)
+
+scala> def f = throw new Exception
+f: Nothing
+
+scala> f
+java.lang.Exception
+  at .f(<console>:7)
+
+scala> """
+
+}