From 95e4631b68a6e2b46ff789d7931a2e7b1e67ab45 Mon Sep 17 00:00:00 2001
From: Liu Fengyun <liu@fengy.me>
Date: Mon, 12 Apr 2021 14:56:21 +0200
Subject: [PATCH] Handle non-local return in trace

---
 .../src/dotty/tools/dotc/reporting/trace.scala  | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/reporting/trace.scala b/compiler/src/dotty/tools/dotc/reporting/trace.scala
index 07a67c2c9cc2..9036ba1c1dc7 100644
--- a/compiler/src/dotty/tools/dotc/reporting/trace.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/trace.scala
@@ -74,18 +74,23 @@ trait TraceSyntax:
       while logctx.reporter.isInstanceOf[StoreReporter] do logctx = logctx.outer
       def margin = ctx.base.indentTab * ctx.base.indent
       def doLog(s: String) = if isForced then println(s) else report.log(s)
-      def finalize(result: Any, note: String) =
+      def finalize(msg: String) =
         if !finalized then
           ctx.base.indent -= 1
-          doLog(s"$margin${trailing(result)}$note")
+          doLog(s"$margin$msg")
           finalized = true
       try
         doLog(s"$margin$leading")
         ctx.base.indent += 1
         val res = op
-        finalize(res, "")
+        finalize(trailing(res))
         res
-      catch case ex: Throwable =>
-        finalize("<missing>", s" (with exception $ex)")
-        throw ex
+      catch
+        case ex: runtime.NonLocalReturnControl[T] =>
+          finalize(trailing(ex.value))
+          throw ex
+        case ex: Throwable =>
+          val msg = s"<== $q = <missing> (with exception $ex)"
+          finalize(msg)
+          throw ex
 end TraceSyntax