Report UNUSED_DESTRUCTURED_PARAMETER_ENTRY

on destructured lambda parameters

 #KT-14347 Fixed

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowInformationProvider.kt

@@ -602,11 +602,17 @@ class ControlFlowInformationProvider private constructor(
     ) {
         element.nameIdentifier ?: return
         if (!VariableUseState.isUsed(variableUseState)) {
-            if (!element.isSingleUnderscore && KtPsiUtil.isRemovableVariableDeclaration(element)) {
-                report(Errors.UNUSED_VARIABLE.on(element, variableDescriptor), ctxt)
-            }
-            else if (element is KtParameter) {
-                processUnusedParameter(ctxt, element, variableDescriptor)
+            if (element.isSingleUnderscore) return
+            when {
+                // KtDestructuringDeclarationEntry -> KtDestructuringDeclaration -> KtParameter -> KtParameterList
+                element is KtDestructuringDeclarationEntry && element.parent?.parent?.parent is KtParameterList ->
+                    report(Errors.UNUSED_DESTRUCTURED_PARAMETER_ENTRY.on(element, variableDescriptor), ctxt)
+
+                KtPsiUtil.isRemovableVariableDeclaration(element) ->
+                    report(Errors.UNUSED_VARIABLE.on(element, variableDescriptor), ctxt)
+
+                element is KtParameter ->
+                    processUnusedParameter(ctxt, element, variableDescriptor)
             }
         }
         else if (variableUseState === ONLY_WRITTEN_NEVER_READ && KtPsiUtil.isRemovableVariableDeclaration(element)) {
@@ -626,7 +632,6 @@ class ControlFlowInformationProvider private constructor(
 
     private fun processUnusedParameter(ctxt: VariableUseContext, element: KtParameter, variableDescriptor: VariableDescriptor) {
         val owner = element.parent?.parent
-        if (element.isSingleUnderscore) return
         when (owner) {
             is KtPrimaryConstructor -> if (!element.hasValOrVar()) {
                 val containingClass = owner.getContainingClassOrObject()

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt

@@ -40,7 +40,10 @@ import org.jetbrains.kotlin.lexer.KtTokens.*
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getQualifiedElementSelector
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
-import org.jetbrains.kotlin.resolve.*
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.BindingContextUtils
+import org.jetbrains.kotlin.resolve.BindingTrace
+import org.jetbrains.kotlin.resolve.CompileTimeConstantUtils
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.ArgumentMatch
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
@@ -49,8 +52,8 @@ import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
 import org.jetbrains.kotlin.resolve.calls.tower.getFakeDescriptorForObject
 import org.jetbrains.kotlin.resolve.calls.util.FakeCallableDescriptorForObject
 import org.jetbrains.kotlin.resolve.constants.evaluate.ConstantExpressionEvaluator
-import org.jetbrains.kotlin.types.expressions.DoubleColonLHS
 import org.jetbrains.kotlin.resolve.scopes.receivers.*
+import org.jetbrains.kotlin.types.expressions.DoubleColonLHS
 import org.jetbrains.kotlin.types.expressions.OperatorConventions
 import java.util.*
 
@@ -970,6 +973,10 @@ class ControlFlowProcessor(private val trace: BindingTrace) {
                 builder.bindLabel(skipDefaultValue)
             }
             generateInitializer(parameter, computePseudoValueForParameter(parameter))
+
+            parameter.destructuringDeclaration?.let {
+                visitDestructuringDeclaration(it, generateWriteForEntries = true)
+            }
         }
 
         private fun computePseudoValueForParameter(parameter: KtParameter): PseudoValue {

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -667,6 +667,8 @@ public interface Errors {
 
     DiagnosticFactory1<KtNamedDeclaration, VariableDescriptor> UNUSED_VARIABLE = DiagnosticFactory1.create(WARNING, DECLARATION_NAME);
     DiagnosticFactory1<KtParameter, VariableDescriptor> UNUSED_PARAMETER = DiagnosticFactory1.create(WARNING, DECLARATION_NAME);
+    DiagnosticFactory1<KtDestructuringDeclarationEntry, VariableDescriptor> UNUSED_DESTRUCTURED_PARAMETER_ENTRY =
+            DiagnosticFactory1.create(WARNING, DECLARATION_NAME);
     DiagnosticFactory2<KtTypeParameter, TypeParameterDescriptor, KotlinType> UNUSED_TYPEALIAS_PARAMETER =
             DiagnosticFactory2.create(WARNING, DECLARATION_NAME);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -275,6 +275,7 @@ public class DefaultErrorMessages {
         MAP.put(UNINITIALIZED_ENUM_COMPANION, "Companion object of enum class ''{0}'' is uninitialized here", NAME);
         MAP.put(UNUSED_VARIABLE, "Variable ''{0}'' is never used", NAME);
         MAP.put(UNUSED_PARAMETER, "Parameter ''{0}'' is never used", NAME);
+        MAP.put(UNUSED_DESTRUCTURED_PARAMETER_ENTRY, "Destructured parameter ''{0}'' is never used", NAME);
         MAP.put(ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE, "Variable ''{0}'' is assigned but never accessed", NAME);
         MAP.put(VARIABLE_WITH_REDUNDANT_INITIALIZER, "Variable ''{0}'' initializer is redundant", NAME);
         MAP.put(UNUSED_VALUE, "The value ''{0}'' assigned to ''{1}'' is never used", ELEMENT_TEXT, FQ_NAMES_IN_TYPES);