From 733a7947d34d6624c0f2afacf519d42edc6fe89c Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Tue, 30 Jan 2024 08:24:04 +0100
Subject: [PATCH] Make tests resilient to exceptions thrown while reporting
 exceptions

Part of #19542. We protect against the case where `Exception.getMessage` or
`Exception.getStackTrace` throw an exception.

[Cherry-picked b427ba660a43161b463a393e49b00e70fce82f58]
---
 .../dotty/tools/vulpix/ParallelTesting.scala  | 26 +++++++++++++------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
index 6636ce1895fb..74a148d8f734 100644
--- a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
+++ b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
@@ -290,15 +290,25 @@ trait ParallelTesting extends RunnerOrchestration { self =>
 
     /** This callback is executed once the compilation of this test source finished */
     private final def onComplete(testSource: TestSource, reportersOrCrash: Try[Seq[TestReporter]], logger: LoggedRunnable): Unit =
-      reportersOrCrash match {
-        case TryFailure(exn) => onFailure(testSource, Nil, logger, Some(s"Fatal compiler crash when compiling: ${testSource.title}:\n${exn.getMessage}${exn.getStackTrace.map("\n\tat " + _).mkString}"))
-        case TrySuccess(reporters) if !reporters.exists(_.skipped) =>
-          maybeFailureMessage(testSource, reporters) match {
-            case Some(msg) => onFailure(testSource, reporters, logger, Option(msg).filter(_.nonEmpty))
-            case None => onSuccess(testSource, reporters, logger)
+      try
+        reportersOrCrash match
+          case TryFailure(exn) => onFailure(testSource, Nil, logger, Some(s"Fatal compiler crash when compiling: ${testSource.title}:\n${exn.getMessage}${exn.getStackTrace.map("\n\tat " + _).mkString}"))
+          case TrySuccess(reporters) if !reporters.exists(_.skipped) =>
+            maybeFailureMessage(testSource, reporters) match {
+              case Some(msg) => onFailure(testSource, reporters, logger, Option(msg).filter(_.nonEmpty))
+              case None => onSuccess(testSource, reporters, logger)
+            }
+          case _ =>
+      catch case ex: Throwable =>
+        echo(s"Exception thrown onComplete (probably by a reporter) in $testSource: ${ex.getClass}")
+        Try(ex.printStackTrace())
+          .recover{ _ =>
+            val trace = ex.getStackTrace.map(_.toString) // compute this first in case getStackTrace throws an exception
+            echo(s"${ex.getClass.getName} message could not be printed due to an exception while computing the message.")
+            if trace.nonEmpty then trace.foreach(echo) else echo(s"${ex.getClass.getName} stack trace is empty.")
           }
-        case _ =>
-      }
+          .getOrElse(echo(s"${ex.getClass.getName} stack trace could not be printed due to an exception while printing the stack trace."))
+        failTestSource(testSource)
 
     /**
      * Based on the reporters obtained after the compilation, determines if this test has failed.