Report warning on unused entities that can be renamed to _

Currently it's all about lambda parameters/destructuring entries

 #KT-14347 In Progress

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

@@ -8,7 +8,7 @@ class C {
 }
 
 fun test() {
-    for ((x, <!UNUSED_VARIABLE!>y<!>) in C()) {
+    for ((<!UNUSED_VARIABLE!>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, <!UNUSED_VARIABLE!>y<!>: Int) in <!COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH, COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH!>C()<!>) {
+    for ((<!UNUSED_VARIABLE!>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, <!UNUSED_VARIABLE!>y<!>) in <!COMPONENT_FUNCTION_AMBIGUITY!>C()<!>) {
+    for ((<!UNUSED_VARIABLE!>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, <!UNUSED_VARIABLE!>y<!>) in <!COMPONENT_FUNCTION_MISSING!>C()<!>) {
+    for ((<!UNUSED_VARIABLE!>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, _)<!SYNTAX!><!>) {
+    for ((@A <!UNUSED_VARIABLE!>a<!>, _)<!SYNTAX!><!>) {
 
     }
 }

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

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

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

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

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

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

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

@@ -43,6 +43,8 @@ fun test() {
     val (_, <!NAME_SHADOWING, REDECLARATION!>`_`<!>) = A()
 
     foo(<!TYPE_MISMATCH!>_<!>, y)
+
+    val (<!UNUSED_VARIABLE!>unused<!>, _) = A()
 }
 
 fun foo(<!UNUSED_PARAMETER!>x<!>: Int, <!UNUSED_PARAMETER!>y<!>: String) {}