UNUSED_VARIABLE is now reported only for last entry of destructuring declaration (if applicable) #KT-14221 Fixed

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

@@ -572,7 +572,7 @@ class ControlFlowInformationProvider private constructor(
                     val element = instruction.variableDeclarationElement as? KtNamedDeclaration ?: return@traverse
                     element.nameIdentifier ?: return@traverse
                     if (!VariableUseState.isUsed(variableUseState)) {
-                        if (KtPsiUtil.isVariableNotParameterDeclaration(element)) {
+                        if (KtPsiUtil.isRemovableVariableDeclaration(element)) {
                             report(Errors.UNUSED_VARIABLE.on(element, variableDescriptor), ctxt)
                         }
                         else if (element is KtParameter) {
@@ -607,7 +607,7 @@ class ControlFlowInformationProvider private constructor(
                             }
                         }
                     }
-                    else if (variableUseState === ONLY_WRITTEN_NEVER_READ && KtPsiUtil.isVariableNotParameterDeclaration(element)) {
+                    else if (variableUseState === ONLY_WRITTEN_NEVER_READ && KtPsiUtil.isRemovableVariableDeclaration(element)) {
                         report(Errors.ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE.on(element, variableDescriptor), ctxt)
                     }
                     else if (variableUseState === WRITTEN_AFTER_READ && element is KtVariableDeclaration) {

compiler/frontend/src/org/jetbrains/kotlin/psi/KtPsiUtil.java

@@ -276,12 +276,13 @@ public class KtPsiUtil {
         }
     }
 
-    public static boolean isVariableNotParameterDeclaration(@NotNull KtDeclaration declaration) {
+    public static boolean isRemovableVariableDeclaration(@NotNull KtDeclaration declaration) {
         if (!(declaration instanceof KtVariableDeclaration)) return false;
         if (declaration instanceof KtProperty) return true;
         assert declaration instanceof KtDestructuringDeclarationEntry;
-        KtDestructuringDeclarationEntry multiDeclarationEntry = (KtDestructuringDeclarationEntry) declaration;
+        KtDestructuringDeclaration parentDeclaration = (KtDestructuringDeclaration) declaration.getParent();
-        return !(multiDeclarationEntry.getParent().getParent().getParent() instanceof KtForExpression);
+        List<KtDestructuringDeclarationEntry> entries = parentDeclaration.getEntries();
+        return entries.size() > 1 && entries.get(entries.size() - 1) == declaration;
     }
 
     @Nullable

compiler/testData/diagnostics/tests/UnusedInDestructuring.kt

@@ -0,0 +1,9 @@
+data class D(val x: Int, val y: Int, val z: Int)
+fun foo(): Int {
+    val (x, y, z) = D(1, 2, 3)
+    return y + z // x is not used, but we cannot do anything with it
+}
+fun bar(): Int {
+    val (x, y, <!UNUSED_VARIABLE!>z<!>) = D(1, 2, 3)
+    return y + x // z is not used
+}

compiler/testData/diagnostics/tests/UnusedInDestructuring.txt

@@ -0,0 +1,18 @@
+package
+
+public fun bar(): kotlin.Int
+public fun foo(): kotlin.Int
+
+public final data class D {
+    public constructor D(/*0*/ x: kotlin.Int, /*1*/ y: kotlin.Int, /*2*/ z: kotlin.Int)
+    public final val x: kotlin.Int
+    public final val y: kotlin.Int
+    public final val z: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final operator /*synthesized*/ fun component2(): kotlin.Int
+    public final operator /*synthesized*/ fun component3(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ x: kotlin.Int = ..., /*1*/ y: kotlin.Int = ..., /*2*/ z: kotlin.Int = ...): D
+    public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*synthesized*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/annotations/forParameterAnnotationResolve.kt

@@ -8,7 +8,7 @@ fun foo() {
     for (@Ann(1) i in 1..100) {}
     for (@Ann(2) i in 1..100) {}
 
-    for (<!WRONG_ANNOTATION_TARGET!>@Ann(3)<!> (x, @Ann(4) y) in bar()) {}
+    for (<!WRONG_ANNOTATION_TARGET!>@Ann(3)<!> (x, @Ann(4) <!UNUSED_VARIABLE!>y<!>) in bar()) {}
 
-    for (@<!UNRESOLVED_REFERENCE!>Err<!>() (x,y) in bar()) {}
+    for (@<!UNRESOLVED_REFERENCE!>Err<!>() (x,<!UNUSED_VARIABLE!>y<!>) in bar()) {}
 }

compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.kt

@@ -22,11 +22,11 @@ fun f() {
 
     }
 
-    for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>val<!> (i,j) in Coll()) {
+    for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>val<!> (i,<!UNUSED_VARIABLE!>j<!>) in Coll()) {
 
     }
 
-    for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>var<!> (i,j) in Coll()) {
+    for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>var<!> (i,<!UNUSED_VARIABLE!>j<!>) in Coll()) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/ComponentFunctionReturnTypeMismatch.kt

@@ -4,5 +4,5 @@ class A {
 }
 
 fun a(aa : A) {
-    val (<!UNUSED_VARIABLE!>a<!>: String, <!UNUSED_VARIABLE!>b1<!>: String) = <!COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH, COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH!>aa<!>
+    val (a: String, <!UNUSED_VARIABLE!>b1<!>: String) = <!COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH, COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH!>aa<!>
 }

compiler/testData/diagnostics/tests/declarationChecks/DataFlowInfoInMultiDecl.kt

@@ -5,10 +5,10 @@ class A {
 
 fun a(aa : A?, b : Any) {
     if (aa != null) {
-        val (<!UNUSED_VARIABLE!>a1<!>, <!UNUSED_VARIABLE!>b1<!>) = <!DEBUG_INFO_SMARTCAST!>aa<!>;
+        val (a1, <!UNUSED_VARIABLE!>b1<!>) = <!DEBUG_INFO_SMARTCAST!>aa<!>;
     }
 
     if (b is A) {
-        val (<!UNUSED_VARIABLE!>a1<!>, <!UNUSED_VARIABLE!>b1<!>) = <!DEBUG_INFO_SMARTCAST!>b<!>;
+        val (a1, <!UNUSED_VARIABLE!>b1<!>) = <!DEBUG_INFO_SMARTCAST!>b<!>;
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/RedeclarationsInMultiDecl.kt

@@ -4,11 +4,11 @@ class A {
 }
 
 fun a() {
-    val (<!REDECLARATION, UNUSED_VARIABLE!>a<!>, <!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>a<!>) = A()
+    val (<!REDECLARATION!>a<!>, <!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>a<!>) = A()
-    val (<!UNUSED_VARIABLE!>x<!>, <!REDECLARATION, UNUSED_VARIABLE!>y<!>) = A();
+    val (x, <!REDECLARATION, UNUSED_VARIABLE!>y<!>) = A();
     val <!REDECLARATION!>b<!> = 1
     use(b)
-    val (<!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>b<!>, <!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>y<!>) = A();
+    val (<!NAME_SHADOWING, REDECLARATION!>b<!>, <!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>y<!>) = A();
 }
 
 

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/DoubleDeclForLoop.kt

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((x, y) in C()) {
+    for ((x, <!UNUSED_VARIABLE!>y<!>) in C()) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/FolLoopTypeComponentTypeMismatch.kt

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((x: Double, y: Int) in <!COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH, COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH!>C()<!>) {
+    for ((x: Double, <!UNUSED_VARIABLE!>y<!>: Int) in <!COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH, COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH!>C()<!>) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionAmbiguity.kt

@@ -9,7 +9,7 @@ class C {
 }
 
 fun test() {
-    for ((x, y) in <!COMPONENT_FUNCTION_AMBIGUITY!>C()<!>) {
+    for ((x, <!UNUSED_VARIABLE!>y<!>) in <!COMPONENT_FUNCTION_AMBIGUITY!>C()<!>) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionMissing.kt

@@ -7,7 +7,7 @@ class C {
 }
 
 fun test() {
-    for ((x, y) in <!COMPONENT_FUNCTION_MISSING!>C()<!>) {
+    for ((x, <!UNUSED_VARIABLE!>y<!>) in <!COMPONENT_FUNCTION_MISSING!>C()<!>) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopMissingLoopParameter.kt

@@ -6,7 +6,7 @@ fun useDeclaredVariables() {
 }
 
 fun checkersShouldRun() {
-    for ((@A a, <!UNDERSCORE_IS_RESERVED!>_<!>)<!SYNTAX!><!>) {
+    for ((@A a, <!UNDERSCORE_IS_RESERVED, UNUSED_VARIABLE!>_<!>)<!SYNTAX!><!>) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopWithExtensions.kt

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((x, y) in C()) {
+    for ((x, <!UNUSED_VARIABLE!>y<!>) in C()) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForWithExplicitTypes.kt

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((x: Int, y: Double) in C()) {
+    for ((x: Int, <!UNUSED_VARIABLE!>y<!>: Double) in C()) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/RedeclarationInForLoop.kt

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((<!REDECLARATION!>x<!>, <!NAME_SHADOWING, REDECLARATION!>x<!>) in C()) {
+    for ((<!REDECLARATION!>x<!>, <!NAME_SHADOWING, REDECLARATION, UNUSED_VARIABLE!>x<!>) in C()) {
 
     }
 }

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationAssignedUnresolved.kt

@@ -5,7 +5,7 @@ fun useDeclaredVariables() {
 }
 
 fun checkersShouldRun() {
-    val (@A <!UNUSED_VARIABLE!>a<!>, <!UNDERSCORE_IS_RESERVED, UNUSED_VARIABLE!>_<!>) = <!UNRESOLVED_REFERENCE!>unresolved<!>
+    val (@A a, <!UNDERSCORE_IS_RESERVED, UNUSED_VARIABLE!>_<!>) = <!UNRESOLVED_REFERENCE!>unresolved<!>
 }
 
 annotation class A

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationMissingInitializer.kt

@@ -5,7 +5,7 @@ fun useDeclaredVariables() {
 }
 
 fun checkersShouldRun() {
-    <!INITIALIZER_REQUIRED_FOR_DESTRUCTURING_DECLARATION!>val (@A <!UNUSED_VARIABLE!>a<!>, <!UNDERSCORE_IS_RESERVED, UNUSED_VARIABLE!>_<!>)<!>
+    <!INITIALIZER_REQUIRED_FOR_DESTRUCTURING_DECLARATION!>val (@A a, <!UNDERSCORE_IS_RESERVED, UNUSED_VARIABLE!>_<!>)<!>
 }
 
 annotation class A

compiler/testData/diagnostics/tests/declarationChecks/kt2643MultiDeclInControlFlow.kt

@@ -7,7 +7,7 @@ class C {
 }
 
 fun test1(c: C) {
-    val (<!UNUSED_VARIABLE!>a<!>, <!UNUSED_VARIABLE!>b<!>) = c
+    val (a, <!UNUSED_VARIABLE!>b<!>) = c
 }
 
 fun test2(c: C) {
@@ -16,7 +16,7 @@ fun test2(c: C) {
 }
 
 fun test3(c: C) {
-    var (<!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>a<!>, <!UNUSED_VARIABLE!>b<!>) = c
+    var (a, <!UNUSED_VARIABLE!>b<!>) = c
     <!UNUSED_VALUE!>a =<!> 3
 }
 

compiler/testData/diagnostics/tests/shadowing/ShadowMultiDeclarationWithFunParameter.kt

@@ -6,7 +6,7 @@ class A {
 fun foo(a: A, c: Int) {
     val (<!NAME_SHADOWING!>a<!>, b) = a
     val arr = Array(2) { A() }
-    for ((<!NAME_SHADOWING!>c<!>, d) in arr)  {
+    for ((<!NAME_SHADOWING!>c<!>, <!UNUSED_VARIABLE!>d<!>) in arr)  {
         
     }
 

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -745,6 +745,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("UnusedInDestructuring.kt")
+        public void testUnusedInDestructuring() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/UnusedInDestructuring.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("UnusedParameters.kt")
         public void testUnusedParameters() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/UnusedParameters.kt");

idea/testData/checker/Shadowing.kt

@@ -6,9 +6,9 @@ class A {
 fun arrayA(): Array<A> = null!!
 
 fun foo(a: A, <warning>c</warning>: Int) {
-    val (<warning descr="[NAME_SHADOWING] Name shadowed: a"><warning descr="[UNUSED_VARIABLE] Variable 'a' is never used">a</warning></warning>, <warning>b</warning>) = a
+    val (<warning descr="[NAME_SHADOWING] Name shadowed: a">a</warning>, <warning>b</warning>) = a
     val arr = arrayA()
-    for ((<warning descr="[NAME_SHADOWING] Name shadowed: c">c</warning>, d) in arr) {
+    for ((<warning descr="[NAME_SHADOWING] Name shadowed: c">c</warning>, <warning>d</warning>) in arr) {
     }
 }
 

idea/testData/checker/regression/DescructuringDeclarationInForLoop.kt

@@ -1,3 +1,3 @@
 fun main() {
-    for ((i, j)<error>)</error> {}
+    for ((i, <warning>j</warning>)<error>)</error> {}
 }