Debugger: Provide fixed implementation of 'toString()' for lambdas (KT-32691)

idea/jvm-debugger/jvm-debugger-evaluation/src/org/jetbrains/kotlin/idea/debugger/evaluate/classLoading/OrdinaryClassLoadingAdapter.kt

@@ -23,10 +23,9 @@ import com.sun.jdi.ClassLoaderReference
 import com.sun.jdi.ClassType
 import org.jetbrains.kotlin.idea.debugger.evaluate.ExecutionContext
 import org.jetbrains.kotlin.idea.debugger.isDexDebug
-import org.jetbrains.org.objectweb.asm.ClassReader
-import org.jetbrains.org.objectweb.asm.ClassVisitor
-import org.jetbrains.org.objectweb.asm.ClassWriter
-import org.jetbrains.org.objectweb.asm.Opcodes
+import org.jetbrains.org.objectweb.asm.*
+import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter
+import kotlin.jvm.internal.Lambda
 
 class OrdinaryClassLoadingAdapter : ClassLoadingAdapter {
     private companion object {
@@ -37,29 +36,54 @@ class OrdinaryClassLoadingAdapter : ClassLoadingAdapter {
         private val LAMBDA_SUPERCLASSES = listOf(ClassBytes("kotlin.jvm.internal.Lambda"))
 
         // Copied from com.intellij.debugger.ui.impl.watch.CompilingEvaluator.changeSuperToMagicAccessor
-        fun changeSuperToMagicAccessor(bytes: ByteArray): ByteArray {
+        fun patchClass(bytes: ByteArray, useMagicAccessor: Boolean): ByteArray {
             val classWriter = ClassWriter(0)
             val classVisitor = object : ClassVisitor(Opcodes.API_VERSION, classWriter) {
-                override fun visit(
-                    version: Int,
-                    access: Int,
-                    name: String,
-                    signature: String?,
-                    superName: String?,
-                    interfaces: Array<String>?
-                ) {
+                private var superName: String? = null
+
+                override fun visit(version: Int, access: Int, name: String, sig: String?, superName: String?, interfaces: Array<String>?) {
                     var newSuperName = superName
-                    if ("java/lang/Object" == newSuperName) {
+                    if (useMagicAccessor && "java/lang/Object" == newSuperName) {
                         newSuperName = "sun/reflect/MagicAccessorImpl"
                     }
 
-                    super.visit(version, access, name, signature, newSuperName, interfaces)
+                    this.superName = newSuperName
+                    super.visit(version, access, name, sig, newSuperName, interfaces)
+                }
+
+                override fun visitEnd() {
+                    if (superName == "kotlin/jvm/internal/Lambda") {
+                        generateLambdaToString(this)
+                    }
                 }
             }
+
             ClassReader(bytes).accept(classVisitor, 0)
             return classWriter.toByteArray()
         }
 
+        private fun generateLambdaToString(classVisitor: ClassVisitor) {
+            val stringBuilderType = Type.getType(StringBuilder::class.java)
+            val lambdaType = Type.getType(Lambda::class.java)
+
+            val methodVisitor = classVisitor.visitMethod(Opcodes.ACC_PUBLIC, "toString", "()Ljava/lang/String;", null, null)
+            InstructionAdapter(methodVisitor).apply {
+                visitCode()
+                anew(stringBuilderType)
+                dup()
+                invokespecial(stringBuilderType.internalName, "<init>", "()V", false)
+                aconst(lambdaType.className + "#")
+                invokevirtual(stringBuilderType.internalName, "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false)
+                load(0, lambdaType)
+                invokevirtual("java/lang/Object", "hashCode", "()I", false)
+                invokevirtual(stringBuilderType.internalName, "append", "(I)Ljava/lang/StringBuilder;", false)
+                invokevirtual(stringBuilderType.internalName, "toString", "()Ljava/lang/String;", false)
+                areturn(Type.getType(String::class.java))
+                visitMaxs(2, 1)
+                visitEnd()
+            }
+        }
+
         fun useMagicAccessor(context: ExecutionContext): Boolean {
             val rawVersion = context.vm.version()?.substringBefore('_') ?: return false
             val javaVersion = JavaSdkVersion.fromVersionString(rawVersion) ?: return false
@@ -105,7 +129,7 @@ class OrdinaryClassLoadingAdapter : ClassLoadingAdapter {
         }
 
         for ((className, _, bytes) in classesToLoad) {
-            val patchedBytes = if (useMagicAccessor(context)) changeSuperToMagicAccessor(bytes) else bytes
+            val patchedBytes = patchClass(bytes, useMagicAccessor(context))
             defineClass(className, patchedBytes, context, classLoader)
         }
     }

idea/jvm-debugger/jvm-debugger-test/test/org/jetbrains/kotlin/idea/debugger/test/KotlinEvaluateExpressionTestGenerated.java

@@ -315,6 +315,11 @@ public class KotlinEvaluateExpressionTestGenerated extends AbstractKotlinEvaluat
             runTest("idea/jvm-debugger/jvm-debugger-test/testData/evaluation/singleBreakpoint/kt7046localVarInInline.kt");
         }
 
+        @TestMetadata("lambdaToString.kt")
+        public void testLambdaToString() throws Exception {
+            runTest("idea/jvm-debugger/jvm-debugger-test/testData/evaluation/singleBreakpoint/lambdaToString.kt");
+        }
+
         @TestMetadata("localClass.kt")
         public void testLocalClass() throws Exception {
             runTest("idea/jvm-debugger/jvm-debugger-test/testData/evaluation/singleBreakpoint/localClass.kt");

idea/jvm-debugger/jvm-debugger-test/testData/evaluation/singleBreakpoint/lambdaToString.kt

@@ -0,0 +1,20 @@
+fun main() {
+    //Breakpoint!
+    val a = 5
+}
+
+private fun String.removeId(): String {
+    return substringBeforeLast('#') + "#id"
+}
+
+// EXPRESSION: {}.toString().removeId()
+// RESULT: "kotlin.jvm.internal.Lambda#id": Ljava/lang/String;
+
+// EXPRESSION: { 1 + 2 }.toString().removeId()
+// RESULT: "kotlin.jvm.internal.Lambda#id": Ljava/lang/String;
+
+// EXPRESSION: { s: String -> s.toString() }.toString().removeId()
+// RESULT: "kotlin.jvm.internal.Lambda#id": Ljava/lang/String;
+
+// EXPRESSION: { l: List<String> -> l.first() }.toString().removeId()
+// RESULT: "kotlin.jvm.internal.Lambda#id": Ljava/lang/String;

idea/jvm-debugger/jvm-debugger-test/testData/evaluation/singleBreakpoint/lambdaToString.out

@@ -0,0 +1,11 @@
+LineBreakpoint created at lambdaToString.kt:3
+Run Java
+Connected to the target VM
+lambdaToString.kt:3
+Compile bytecode for {}.toString().removeId()
+Compile bytecode for { 1 + 2 }.toString().removeId()
+Compile bytecode for { s: String -> s.toString() }.toString().removeId()
+Compile bytecode for { l: List<String> -> l.first() }.toString().removeId()
+Disconnected from the target VM
+
+Process finished with exit code 0