Add setting for macro evaluation timeouts

Author: nicolasstucki

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -46,6 +46,9 @@ class ScalaSettings extends Settings.SettingGroup {
   val silentWarnings = BooleanSetting("-nowarn", "Silence all warnings.")
   val fromTasty = BooleanSetting("-from-tasty", "Compile classes from tasty in classpath. The arguments are used as class names.")
 
+  /** Macro settings */
+  val macroTimeout = IntSetting("-macro-timeout", "Timeout for the evaluation of a macro in ms", 1000, 1 to Int.MaxValue)
+
   /** Decompiler settings */
   val printTasty = BooleanSetting("-print-tasty", "Prints the raw tasty when decompiling.")
   val printLines = BooleanSetting("-print-lines", "Show source code line numbers.")

compiler/src/dotty/tools/dotc/transform/Splicer.scala

@@ -74,7 +74,8 @@ object Splicer {
 
   private def evaluateLambda(lambda: Seq[Any] => Object, args: Seq[Any], pos: Position)(implicit ctx: Context): Option[scala.quoted.Expr[Nothing]] = {
     try {
-      val res = Sandbox.runInSecuredThread(lambda(args))
+      val timeout = ctx.settings.macroTimeout.value
+      val res = Sandbox.runInSecuredThread(timeout)(lambda(args))
       Some(res.asInstanceOf[scala.quoted.Expr[Nothing]])
     } catch {
       case ex: scala.quoted.QuoteError =>

compiler/src/dotty/tools/dotc/util/Sandbox.scala

@@ -8,10 +8,7 @@ import scala.quoted.QuoteError
 
 object Sandbox {
 
-  /** Timeout in milliseconds */
-  final val timeout = 3000 // TODO add a flag to allow custom timeouts
-
-  def runInSecuredThread[T](thunk: => T): T = {
+  def runInSecuredThread[T](timeout: Int)(thunk: => T): T = {
     runWithSandboxSecurityManager { securityManager =>
       class SandboxThread extends Thread {
         var result: scala.util.Try[T] =