From 26ab5beef05ddbf529946ae3531ae163d6bd1b89 Mon Sep 17 00:00:00 2001
From: leonardo-pilastri-sonarsource
 <115481625+leonardo-pilastri-sonarsource@users.noreply.github.com>
Date: Wed, 11 Sep 2024 16:23:29 +0200
Subject: [PATCH] SONARJAVA-4950 Fix S6204 IndexOutOfBoundsException when
 lombok.val is used (#4857)

---
 .../src/main/java/checks/CollectorsToListCheckSample.java  | 7 +++++++
 .../java/org/sonar/java/checks/CollectorsToListCheck.java  | 6 +++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java b/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
index 35855b746c2..7f017ef33c4 100644
--- a/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
+++ b/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
@@ -8,8 +8,15 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import lombok.val;
 
 public class CollectorsToListCheckSample {
+
+  void lombok_val() {
+    // Lombok val is not supported, in this case the symbolType of the collect method invocation is unknown
+    val unknownSymbolStream = Stream.of("A", "B", "C").collect(Collectors.toList()); // Compliant
+  }
+
   static class ListWrapper {
     List<String> strings;
   }
diff --git a/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java b/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
index 39acd6284d3..729f9318b14 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
@@ -19,6 +19,7 @@
  */
 package org.sonar.java.checks;
 
+import java.util.List;
 import javax.annotation.CheckForNull;
 import org.sonar.check.Rule;
 import org.sonar.java.checks.methods.AbstractMethodDetection;
@@ -107,9 +108,8 @@ private static boolean isInvariantTypeArgument(MethodInvocationTree collectMetho
     if (streamType.isRawType()) {
       return true;
     }
-    Type collectArgType = collectMethodInvocation.symbolType().typeArguments().get(0);
-    Type streamArgType = streamType.typeArguments().get(0);
-    return collectArgType.is(streamArgType.fullyQualifiedName());
+    List<Type> typeArguments = collectMethodInvocation.symbolType().typeArguments();
+    return !typeArguments.isEmpty() && typeArguments.get(0).is(streamType.typeArguments().get(0).fullyQualifiedName());
   }
 
   private void reportIssue(MethodInvocationTree collector, boolean mutable) {