Watches: Hide 'this' if it's a continuation

idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/KotlinStackFrame.kt

@@ -23,6 +23,7 @@ import com.intellij.debugger.jdi.LocalVariableProxyImpl
 import com.intellij.debugger.jdi.StackFrameProxyImpl
 import com.intellij.debugger.ui.impl.watch.MethodsTracker
 import com.intellij.debugger.ui.impl.watch.StackFrameDescriptorImpl
+import com.intellij.xdebugger.frame.XValue
 import com.intellij.xdebugger.frame.XValueChildrenList
 import com.sun.jdi.Value
 import org.jetbrains.kotlin.codegen.AsmUtil
@@ -30,6 +31,11 @@ import org.jetbrains.kotlin.codegen.coroutines.CONTINUATION_PARAMETER_NAME
 import org.jetbrains.kotlin.codegen.inline.INLINE_FUN_VAR_SUFFIX
 import org.jetbrains.kotlin.codegen.inline.isFakeLocalVariableForInline
 import org.jetbrains.kotlin.idea.debugger.evaluate.THIS_NAME
+import org.jetbrains.kotlin.idea.debugger.evaluate.VariableFinder
+import org.jetbrains.kotlin.utils.getSafe
+import java.lang.reflect.Modifier
+import java.util.*
+import org.jetbrains.kotlin.idea.debugger.evaluate.LOG as DebuggerLog
 
 class KotlinStackFrame(frame: StackFrameProxyImpl) : JavaStackFrame(StackFrameDescriptorImpl(frame, MethodsTracker()), true) {
     private val kotlinVariableViewService = ToggleKotlinVariablesState.getService()
@@ -41,6 +47,8 @@ class KotlinStackFrame(frame: StackFrameProxyImpl) : JavaStackFrame(StackFrameDe
 
         val nodeManager = evaluationContext.debugProcess.xdebugProcess!!.nodeManager
 
+        removeThisObjectIfNeeded(evaluationContext, children)
+
         fun addItem(variable: LocalVariableProxyImpl) {
             val variableDescriptor = nodeManager.getLocalVariableDescriptor(null, variable)
             children.add(JavaValue.create(null, variableDescriptor, evaluationContext, nodeManager, false))
@@ -53,6 +61,80 @@ class KotlinStackFrame(frame: StackFrameProxyImpl) : JavaStackFrame(StackFrameDe
         otherVariables.forEach(::addItem)
     }
 
+    private fun removeThisObjectIfNeeded(evaluationContext: EvaluationContextImpl, children: XValueChildrenList) {
+        val thisObject = evaluationContext.frameProxy?.thisObject() ?: return
+        if (!thisObject.type().isSubtype(VariableFinder.CONTINUATION_TYPE)) {
+            return
+        }
+
+        ExistingVariable.find(children, "this")?.remove()
+    }
+
+    // Very Dirty Work-around.
+    // Hopefully, there will be an API for that in 2019.1.
+    private class ExistingVariable(
+        private val children: XValueChildrenList,
+        private val index: Int,
+        private val name: String,
+        private val value: XValue,
+        private val size: Int
+    ) {
+        companion object {
+            fun find(children: XValueChildrenList, name: String): ExistingVariable? {
+                val size = children.size()
+                for (i in 0 until size) {
+                    if (children.getName(i) == name) {
+                        val valueDescriptor = (children.getValue(i) as? JavaValue)?.descriptor
+                        @Suppress("FoldInitializerAndIfToElvis")
+                        if (valueDescriptor !is ThisDescriptorImpl) {
+                            return null
+                        }
+
+                        return ExistingInstanceThis(children, i, name, children.getValue(i), size)
+                    }
+                }
+
+                return null
+            }
+        }
+
+        fun remove() {
+            if (children.size() != size) {
+                throw IllegalStateException("Children list was modified")
+            }
+
+            var namesList: MutableList<*>? = null
+            var valuesList: MutableList<*>? = null
+
+            for (field in XValueChildrenList::class.java.declaredFields) {
+                val mods = field.modifiers
+                if (Modifier.isPrivate(mods) && Modifier.isFinal(mods) && !Modifier.isStatic(mods) && field.type == List::class.java) {
+                    val list = (field.getSafe(children) as? MutableList<*>)?.takeIf { it.size == size } ?: continue
+                    if (list[index] == name) {
+                        namesList = list
+                    } else if (list[index] === value) {
+                        valuesList = list
+                    }
+                }
+
+                if (namesList != null && valuesList != null) {
+                    break
+                }
+            }
+
+            if (namesList == null || valuesList == null) {
+                org.jetbrains.kotlin.idea.debugger.evaluate.LOG.error(
+                    "Can't find name/value lists, existing fields: "
+                            + Arrays.toString(XValueChildrenList::class.java.declaredFields)
+                )
+                return
+            }
+
+            namesList.removeAt(index)
+            valuesList.removeAt(index)
+        }
+    }
+
     override fun getVisibleVariables(): List<LocalVariableProxyImpl> {
         val allVisibleVariables = super.getStackFrameProxy().safeVisibleVariables()
 

idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/evaluate/VariableFinder.kt

@@ -34,7 +34,7 @@ import com.sun.jdi.Type as JdiType
 class VariableFinder private constructor(private val context: EvaluationContextImpl, private val frameProxy: StackFrameProxyImpl) {
     companion object {
         private val COROUTINE_CONTEXT_SIMPLE_NAME = COROUTINE_CONTEXT_1_3_FQ_NAME.shortName().asString()
-        private val CONTINUATION_TYPE = AsmType.getType(Continuation::class.java)
+        val CONTINUATION_TYPE: AsmType = AsmType.getType(Continuation::class.java)
 
         val SUSPEND_LAMBDA_CLASSES = listOf(
             "kotlin.coroutines.jvm.internal.SuspendLambda",

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/frame/hideContinuationThis.kt

@@ -0,0 +1,13 @@
+package hideContinuationThis
+
+suspend fun main() {
+    foo()
+}
+
+var foo: suspend () -> Unit = {
+    //Breakpoint!
+    val a = 5
+}
+
+// PRINT_FRAME
+// SHOW_KOTLIN_VARIABLES

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/frame/hideContinuationThis.out

@@ -0,0 +1,23 @@
+LineBreakpoint created at hideContinuationThis.kt:9
+Run Java
+Connected to the target VM
+hideContinuationThis.kt:9
+package hideContinuationThis
+
+suspend fun main() {
+    foo()
+}
+
+var foo: suspend () -> Unit = {
+    //Breakpoint!
+    val a = 5
+}
+
+// PRINT_FRAME
+// SHOW_KOTLIN_VARIABLES
+ frame    = invokeSuspend:9, HideContinuationThisKt$foo$1 {hideContinuationThis}
+   local    = result: java.lang.Object = {kotlin.Unit@uniqueID}kotlin.Unit (sp = null)
+              - No fields to display
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/KotlinEvaluateExpressionTestGenerated.java

@@ -735,6 +735,11 @@ public class KotlinEvaluateExpressionTestGenerated extends AbstractKotlinEvaluat
                 runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/frame/frameThis0This0.kt");
             }
 
+            @TestMetadata("hideContinuationThis.kt")
+            public void testHideContinuationThis() throws Exception {
+                runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/frame/hideContinuationThis.kt");
+            }
+
             @TestMetadata("suspendContinuation.kt")
             public void testSuspendContinuation() throws Exception {
                 runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/frame/suspendContinuation.kt");