From 4f17f83d2f0fca496d82b2b517f45f5b032c7ef3 Mon Sep 17 00:00:00 2001
From: Tomas Zezula <tomas.zezula@oracle.com>
Date: Mon, 26 Jul 2021 14:12:59 +0200
Subject: [PATCH] [GR-32787] PolyglotException should use interop messages to
 obtain exception message.

---
 .../test/polyglot/PolyglotExceptionTest.java  | 46 ++++++++++++++++++-
 .../polyglot/PolyglotExceptionImpl.java       | 41 ++++++++---------
 2 files changed, 64 insertions(+), 23 deletions(-)

diff --git a/truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/polyglot/PolyglotExceptionTest.java b/truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/polyglot/PolyglotExceptionTest.java
index 09e4f5679278..825e8b58a7b2 100644
--- a/truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/polyglot/PolyglotExceptionTest.java
+++ b/truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/polyglot/PolyglotExceptionTest.java
@@ -94,12 +94,29 @@
 
 public class PolyglotExceptionTest extends AbstractPolyglotTest {
 
+    @ExportLibrary(InteropLibrary.class)
     @SuppressWarnings("serial")
-    private static class TestGuestError extends AbstractTruffleException {
+    static class TestGuestError extends AbstractTruffleException {
+
+        String exceptionMessage;
 
         TestGuestError() {
             super("MyError");
         }
+
+        @ExportMessage
+        boolean hasExceptionMessage() {
+            return exceptionMessage != null;
+        }
+
+        @ExportMessage
+        Object getExceptionMessage() throws UnsupportedMessageException {
+            if (exceptionMessage != null) {
+                return exceptionMessage;
+            } else {
+                throw UnsupportedMessageException.create();
+            }
+        }
     }
 
     @Test
@@ -587,6 +604,33 @@ public String getName() {
         executorService.awaitTermination(100, TimeUnit.SECONDS);
     }
 
+    @Test
+    public void testExceptionMessage() {
+        try (Context ctx = Context.create()) {
+            TestGuestError guestError = new TestGuestError();
+            guestError.exceptionMessage = "interop exception message";
+            CauseErrorTruffleObject causeError = new CauseErrorTruffleObject();
+            causeError.thrownError = guestError;
+            Value throwError = ctx.asValue(causeError);
+            try {
+                throwError.execute();
+                Assert.fail();
+            } catch (PolyglotException e) {
+                Assert.assertEquals("interop exception message", e.getMessage());
+                Assert.assertTrue(e.isGuestException());
+            }
+
+            guestError.exceptionMessage = null;
+            try {
+                throwError.execute();
+                Assert.fail();
+            } catch (PolyglotException e) {
+                Assert.assertEquals("MyError", e.getMessage());
+                Assert.assertTrue(e.isGuestException());
+            }
+        }
+    }
+
     abstract static class BaseNode extends Node {
         abstract Object execute(VirtualFrame frame);
     }
diff --git a/truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotExceptionImpl.java b/truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotExceptionImpl.java
index 3e03dda17120..543a4d6212a7 100644
--- a/truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotExceptionImpl.java
+++ b/truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotExceptionImpl.java
@@ -123,6 +123,7 @@ final class PolyglotExceptionImpl {
         this.guestFrames = TruffleStackTrace.getStackTrace(original);
         this.showInternalStackFrames = engine == null ? false : engine.engineOptionValues.get(PolyglotEngineOptions.ShowInternalStackFrames);
         Error resourceLimitError = getResourceLimitError(engine, exception);
+        String exceptionMessage = null;
         InteropLibrary interop;
         if (allowInterop && (interop = InteropLibrary.getUncached()).isException(exception)) {
             try {
@@ -138,7 +139,9 @@ final class PolyglotExceptionImpl {
                 this.exitStatus = this.exit ? interop.getExceptionExitStatus(exception) : 0;
                 this.incompleteSource = this.syntaxError ? interop.isExceptionIncompleteSource(exception) : false;
                 this.interrupted = (exceptionType == ExceptionType.INTERRUPT) && !this.cancelled;
-
+                if (interop.hasExceptionMessage(exception)) {
+                    exceptionMessage = interop.asString(interop.getExceptionMessage(exception));
+                }
                 if (interop.hasSourceLocation(exception)) {
                     this.sourceLocation = newSourceSection(interop.getSourceLocation(exception));
                 } else {
@@ -204,28 +207,22 @@ final class PolyglotExceptionImpl {
             }
             this.sourceLocation = location != null ? newSourceSection(location) : null;
         }
-        if (isHostException()) {
-            this.message = asHostException().getMessage();
-        } else {
-            if (internal) {
-                this.message = exception.toString();
-            } else {
-                String exceptionMessage = exception.getMessage();
-                if (exceptionMessage != null) {
-                    this.message = exceptionMessage;
-                } else if (resourceLimitError != null) {
-                    String resourceExhaustedMessage = "Resource exhausted";
-                    if (resourceLimitError instanceof StackOverflowError) {
-                        resourceExhaustedMessage += ": Stack overflow";
-                    }
-                    if (resourceLimitError instanceof OutOfMemoryError) {
-                        resourceExhaustedMessage += ": Out of memory";
-                    }
-                    this.message = resourceExhaustedMessage;
-                } else {
-                    this.message = null;
-                }
+        if (exceptionMessage == null) {
+            exceptionMessage = isHostException() ? asHostException().getMessage() : internal ? exception.toString() : exception.getMessage();
+        }
+        if (exceptionMessage != null) {
+            this.message = exceptionMessage;
+        } else if (resourceLimitError != null) {
+            String resourceExhaustedMessage = "Resource exhausted";
+            if (resourceLimitError instanceof StackOverflowError) {
+                resourceExhaustedMessage += ": Stack overflow";
             }
+            if (resourceLimitError instanceof OutOfMemoryError) {
+                resourceExhaustedMessage += ": Out of memory";
+            }
+            this.message = resourceExhaustedMessage;
+        } else {
+            this.message = null;
         }
 
         // late materialization of host frames. only needed if polyglot exceptions cross the