Add test for missing synthetic Java fields

kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/processor/ReachableAnnotationsFromGivenClasses.kt

diff --git a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/processor/ReachableAnnotationsFromGivenClasses.kt b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/processor/ReachableAnnotationsFromGivenClasses.kt
new file mode 100644
index 0000000..3e6e040
--- /dev/null
+++ b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/processor/ReachableAnnotationsFromGivenClasses.kt
@@ -0,0 +1,55 @@
+package com.google.devtools.ksp.processor
+
+import com.google.devtools.ksp.getClassDeclarationByName
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSAnnotation
+import com.google.devtools.ksp.symbol.KSDeclaration
+import com.google.devtools.ksp.symbol.KSNode
+import com.google.devtools.ksp.visitor.KSTopDownVisitor
+
+class ReachableAnnotationsFromGivenClasses(
+    val classNames: List<String>,
+    override val enableNewFeatures: Boolean
+) : AbstractTestProcessor() {
+
+    private val results = mutableListOf<String>()
+
+    override fun toResult(): List<String> = results
+
+    override fun process(resolver: Resolver): List<KSAnnotated> {
+        val seenNames = mutableSetOf<String>()
+        val seenNodes = mutableSetOf<KSNode>()
+        val visitor = DeclarationVisitor(seenNodes)
+        classNames.forEach { className ->
+            resolver
+                .getClassDeclarationByName(className)
+                ?.accept(visitor, seenNames)
+        }
+        results.addAll(seenNames)
+        return emptyList()
+    }
+
+    inner class DeclarationVisitor(val seen: MutableSet<KSNode>) :
+        KSTopDownVisitor<MutableSet<String>, Unit>(enableNewFeatures) {
+        override fun defaultHandler(
+            node: KSNode,
+            data: MutableSet<String>
+        ) {
+            seen.add(node)
+        }
+
+        override fun visitDeclaration(declaration: KSDeclaration, data: MutableSet<String>) {
+            data.add(declaration.qualifiedName?.asString() ?: declaration.simpleName.asString())
+            super.visitDeclaration(declaration, data)
+        }
+
+        override fun visitAnnotation(annotation: KSAnnotation, data: MutableSet<String>) {
+            super.visitAnnotation(annotation, data)
+            val declaration = annotation.annotationType.resolve().declaration
+            if (!seen.contains(declaration)) {
+                declaration.accept(this, data)
+            }
+        }
+    }
+}

kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/AAConfiguredUnitTestSuite.kt

diff --git a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/AAConfiguredUnitTestSuite.kt b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/AAConfiguredUnitTestSuite.kt
index a0c0c47..2a3ecd1 100644
--- a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/AAConfiguredUnitTestSuite.kt
+++ b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/AAConfiguredUnitTestSuite.kt
@@ -17,6 +17,8 @@
 
 package com.google.devtools.ksp.test
 
+import com.google.devtools.ksp.test.annotations.Bug
+import com.google.devtools.ksp.test.annotations.BugState
 import org.jetbrains.kotlin.test.TestMetadata
 import org.junit.jupiter.api.Test
 
@@ -61,6 +63,18 @@
     }
 }
 
-class AAConfiguredUnitTestSuite : AAConfiguredUnitTestSuiteBase(enableNewFeatures = false)
+class AAConfiguredUnitTestSuite : AAConfiguredUnitTestSuiteBase(enableNewFeatures = false) {
+    @TestMetadata("javaBackingFieldUsedInKotlin.kt")
+    @Test
+    override fun testJavaBackingFieldUsedInKotlin() {
+        runTest("$AA_PATH/javaBackingFieldUsedInKotlin.kt")
+    }
+}
 
-class AAConfiguredNewFeaturesUnitTestSuite : AAConfiguredUnitTestSuiteBase(enableNewFeatures = true)
+class AAConfiguredNewFeaturesUnitTestSuite : AAConfiguredUnitTestSuiteBase(enableNewFeatures = true) {
+    @TestMetadata("javaBackingFieldUsedInKotlin.kt")
+    @Test
+    override fun testJavaBackingFieldUsedInKotlin() {
+        runFailingTest("$AA_PATH/javaBackingFieldUsedInKotlin.kt")
+    }
+}

kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/KSPUnitTestSuite.kt

diff --git a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/KSPUnitTestSuite.kt b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/KSPUnitTestSuite.kt
index 055ffb3..addb4ee 100644
--- a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/KSPUnitTestSuite.kt
+++ b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/KSPUnitTestSuite.kt
@@ -510,6 +510,11 @@
         runTest("$AA_PATH/isMutable.kt")
     }
 
+    @Bug("https://github.com/google/ksp/issues/3191", BugState.OPEN)
+    @TestMetadata("javaBackingFieldUsedInKotlin.kt")
+    @Test
+    abstract fun testJavaBackingFieldUsedInKotlin()
+
     @Bug("https://github.com/google/ksp/issues/3123", BugState.OPEN)
     @Bug("https://github.com/google/ksp/issues/3125", BugState.FIXED)
     @Bug("https://github.com/google/ksp/issues/3155", BugState.OPEN)

kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/PsiConfiguredUnitTestSuite.kt

diff --git a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/PsiConfiguredUnitTestSuite.kt b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/PsiConfiguredUnitTestSuite.kt
index 2e9dd94..2da81a6 100644
--- a/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/PsiConfiguredUnitTestSuite.kt
+++ b/kotlin-analysis-api/src/test/kotlin/com/google/devtools/ksp/test/PsiConfiguredUnitTestSuite.kt
@@ -61,6 +61,18 @@
     }
 }
 
-class PsiConfiguredUnitTestSuite : PsiConfiguredUnitTestSuiteBase(enableNewFeatures = false)
+class PsiConfiguredUnitTestSuite : PsiConfiguredUnitTestSuiteBase(enableNewFeatures = false) {
+    @TestMetadata("javaBackingFieldUsedInKotlin.kt")
+    @Test
+    override fun testJavaBackingFieldUsedInKotlin() {
+        runTest("$AA_PATH/javaBackingFieldUsedInKotlin.kt")
+    }
+}
 
-class PsiConfiguredNewFeaturesUnitTestSuite : PsiConfiguredUnitTestSuiteBase(enableNewFeatures = true)
+class PsiConfiguredNewFeaturesUnitTestSuite : PsiConfiguredUnitTestSuiteBase(enableNewFeatures = true) {
+    @TestMetadata("javaBackingFieldUsedInKotlin.kt")
+    @Test
+    override fun testJavaBackingFieldUsedInKotlin() {
+        runFailingTest("$AA_PATH/javaBackingFieldUsedInKotlin.kt")
+    }
+}

kotlin-analysis-api/testData/javaBackingFieldUsedInKotlin.kt

diff --git a/kotlin-analysis-api/testData/javaBackingFieldUsedInKotlin.kt b/kotlin-analysis-api/testData/javaBackingFieldUsedInKotlin.kt
new file mode 100644
index 0000000..4dee270
--- /dev/null
+++ b/kotlin-analysis-api/testData/javaBackingFieldUsedInKotlin.kt
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// TEST PROCESSOR: ReachableAnnotationsFromGivenClasses
+// PROCESSOR INPUT: MyClass
+// EXPECTED:
+// MyClass
+// com.example.MyAnnotation
+// EXPECT CURRENT: com.example.MyAnnotation.myValue
+// EXPECT NEXT: com.example.MyAnnotation.myValue.field
+// EXPECT NEXT: com.example.MyAnnotation.myValue
+// <init>
+// END
+
+// FILE: MyAnnotation.java
+package com.example;
+
+public @interface MyAnnotation {
+    int myValue() default 42;
+}
+
+// FILE: MyClass.kt
+import com.example.MyAnnotation
+
+@MyAnnotation
+class MyClass