Fix #9801: Make sure the errors are reported

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

@@ -65,15 +65,15 @@ object Splicer {
           EmptyTree
         case ex: StopInterpretation =>
           report.error(ex.msg, ex.pos)
-          EmptyTree
+          ref(defn.Predef_undefined).withType(ErrorType(ex.msg))
         case NonFatal(ex) =>
           val msg =
             s"""Failed to evaluate macro.
                |  Caused by ${ex.getClass}: ${if (ex.getMessage == null) "" else ex.getMessage}
                |    ${ex.getStackTrace.takeWhile(_.getClassName != "dotty.tools.dotc.transform.Splicer$").drop(1).mkString("\n    ")}
              """.stripMargin
           report.error(msg, pos)
-          EmptyTree
+          ref(defn.Predef_undefined).withType(ErrorType(msg))
       }
   }
 

tests/neg-macros/i9801/Macro_1.scala

@@ -0,0 +1,20 @@
+import scala.quoted._
+
+def f() = ()
+
+def triggerStackOverflow(n: Int): Expr[Double] = {
+  val r = triggerStackOverflow(n - 1)
+  f()
+  r
+}
+
+inline def loop(inline prog: Double): Double = ${impl('prog)}
+
+def impl(prog: Expr[Double])(using QuoteContext) : Expr[Double] =
+  try {
+    triggerStackOverflow(0)
+  } catch {
+    case e =>
+      qctx.tasty.error(e.getMessage, prog.unseal.pos)
+      '{ 42.0 }
+  }

tests/neg-macros/i9801/Test_2.scala

@@ -0,0 +1 @@
+def test: Unit = loop(4) // error

tests/neg-macros/i9801b/Macro_1.scala

@@ -0,0 +1,14 @@
+import scala.quoted._
+
+def f() = ()
+
+def triggerStackOverflow(n: Int): Expr[Double] = {
+  val r = triggerStackOverflow(n - 1)
+  f()
+  r
+}
+
+inline def loop(inline prog: Double): Double = ${impl('prog)}
+
+def impl(prog: Expr[Double])(using QuoteContext) : Expr[Double] =
+  triggerStackOverflow(0)

tests/neg-macros/i9801b/Test_2.scala

@@ -0,0 +1 @@
+def test: Unit = loop(4) // error