From df6d4f358ad388fe6512b264111f821e4e8f4845 Mon Sep 17 00:00:00 2001
From: Dmitry Petrov <dmitry.petrov@jetbrains.com>
Date: Tue, 24 Jul 2018 15:58:10 +0300
Subject: [PATCH] KT-22274 report warning on labels that can't be referenced

Labels are meaningful only if they can be referenced by 'break',
'continue', or 'return' expressions.
---
 .../kotlin/cfg/ControlFlowProcessor.kt        | 11 ++++++
 .../jetbrains/kotlin/diagnostics/Errors.java  |  2 +
 .../rendering/DefaultErrorMessages.java       |  2 +
 .../diagnostics/tests/BreakContinue.kt        |  4 +-
 compiler/testData/diagnostics/tests/Casts.kt  |  2 +-
 .../tests/FunctionCalleeExpressions.kt        |  2 +-
 .../diagnostics/tests/LValueAssignment.kt     | 10 ++---
 .../tests/PackageInExpressionPosition.kt      |  2 +-
 .../diagnostics/tests/ReserveYield2.kt        |  4 +-
 .../testData/diagnostics/tests/Underscore.kt  |  2 +-
 .../deadCode/commentsInDeadCode.kt            |  2 +-
 .../referenceToPropertyInitializer.kt         |  2 +-
 .../notAFunctionLabel_after.kt                |  4 +-
 .../notAFunctionLabel_before.kt               |  4 +-
 .../tests/controlStructures/redundantLabel.kt | 39 +++++++++++++++++++
 .../controlStructures/redundantLabel.txt      | 21 ++++++++++
 .../inference/labeledDelegatedExpression.kt   |  2 +-
 .../deparenthesize/ParenthesizedVariable.kt   |  2 +-
 .../checkDeparenthesizedType.kt               | 10 ++---
 .../tests/deparenthesize/labeledSafeCall.kt   |  2 +-
 .../expectedTypeFromCastParenthesized.kt      |  2 +-
 .../diagnostics/tests/inline/labeled.kt       |  8 ++--
 .../diagnostics/tests/inline/parenthesized.kt |  4 +-
 .../TypeMismatchOnUnaryOperations.kt          |  4 +-
 .../nestedCalls/argumentsInParentheses.kt     |  4 +-
 .../senselessComparison/parenthesized.kt      |  8 ++--
 .../checkers/DiagnosticsTestGenerated.java    |  5 +++
 .../DiagnosticsUsingJavacTestGenerated.java   |  5 +++
 28 files changed, 127 insertions(+), 42 deletions(-)
 create mode 100644 compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt
 create mode 100644 compiler/testData/diagnostics/tests/controlStructures/redundantLabel.txt

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt b/compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt
index 7324ef2f1d2..9f2ee0fd7d4 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt
@@ -298,6 +298,17 @@ class ControlFlowProcessor(
                 generateInstructions(baseExpression)
                 copyValue(baseExpression, expression)
             }
+
+            val labelNameExpression = expression.getTargetLabel()
+            if (labelNameExpression != null) {
+                val deparenthesizedBaseExpression = KtPsiUtil.deparenthesize(expression)
+                if (deparenthesizedBaseExpression !is KtLambdaExpression &&
+                    deparenthesizedBaseExpression !is KtLoopExpression &&
+                    deparenthesizedBaseExpression !is KtNamedFunction
+                ) {
+                    trace.report(Errors.REDUNDANT_LABEL_WARNING.on(labelNameExpression))
+                }
+            }
         }
 
         override fun visitBinaryExpression(expression: KtBinaryExpression) {
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
index 97344c48a0a..182337a178b 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
@@ -822,6 +822,8 @@ public interface Errors {
     DiagnosticFactory0<KtExpressionWithLabel> NOT_A_FUNCTION_LABEL = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtExpressionWithLabel> NOT_A_FUNCTION_LABEL_WARNING = DiagnosticFactory0.create(WARNING);
 
+    DiagnosticFactory0<KtElement> REDUNDANT_LABEL_WARNING = DiagnosticFactory0.create(WARNING);
+
     // Control flow / Data flow
 
     DiagnosticFactory1<KtElement, List<TextRange>> UNREACHABLE_CODE = DiagnosticFactory1.create(
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
index 6f1982dea51..6119a71fbf8 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
@@ -602,6 +602,8 @@ public class DefaultErrorMessages {
         MAP.put(NOT_A_FUNCTION_LABEL, "Target label does not denote a function");
         MAP.put(NOT_A_FUNCTION_LABEL_WARNING, "Target label does not denote a function");
 
+        MAP.put(REDUNDANT_LABEL_WARNING, "Label is redundant, because it can not be referenced in either ''break'', ''continue'', or ''return'' expression");
+
         MAP.put(ANONYMOUS_INITIALIZER_IN_INTERFACE, "Anonymous initializers are not allowed in interfaces");
         MAP.put(NULLABLE_SUPERTYPE, "A supertype cannot be nullable");
         MAP.put(DYNAMIC_SUPERTYPE, "A supertype cannot be dynamic");
diff --git a/compiler/testData/diagnostics/tests/BreakContinue.kt b/compiler/testData/diagnostics/tests/BreakContinue.kt
index 333f9ea024b..1916021cae2 100644
--- a/compiler/testData/diagnostics/tests/BreakContinue.kt
+++ b/compiler/testData/diagnostics/tests/BreakContinue.kt
@@ -2,7 +2,7 @@ class C {
 
     fun f (<!UNUSED_PARAMETER!>a<!> : Boolean, <!UNUSED_PARAMETER!>b<!> : Boolean) {
         b@ while (true)
-          a@ {
+          <!REDUNDANT_LABEL_WARNING!>a@<!> {
             <!NOT_A_LOOP_LABEL!>break@f<!>
             break
             <!UNREACHABLE_CODE!>break@b<!>
@@ -12,7 +12,7 @@ class C {
         <!BREAK_OR_CONTINUE_OUTSIDE_A_LOOP!>continue<!>
 
         b@ while (true)
-          a@ {
+          <!REDUNDANT_LABEL_WARNING!>a@<!> {
             <!NOT_A_LOOP_LABEL!>continue@f<!>
             continue
             <!UNREACHABLE_CODE!>continue@b<!>
diff --git a/compiler/testData/diagnostics/tests/Casts.kt b/compiler/testData/diagnostics/tests/Casts.kt
index e3826b63ff5..96c2679a163 100644
--- a/compiler/testData/diagnostics/tests/Casts.kt
+++ b/compiler/testData/diagnostics/tests/Casts.kt
@@ -17,7 +17,7 @@ fun test() : Unit {
 
   val <!UNUSED_VARIABLE!>s<!> = "" as Any
   ("" as String?)?.length
-  (data@("" as String?))?.length
+  (<!REDUNDANT_LABEL_WARNING!>data@<!>("" as String?))?.length
   (<!WRONG_ANNOTATION_TARGET!>@MustBeDocumented()<!>( "" as String?))?.length
   Unit
 }
diff --git a/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.kt b/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.kt
index 47bdfafefcc..388dc07641e 100644
--- a/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.kt
+++ b/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.kt
@@ -59,7 +59,7 @@ fun main1() {
     {1}();
     (fun (x : Int) = x)(1)
     1.(fun Int.(x : Int) = x)(1);
-    l@{1}()
+    <!OI;REDUNDANT_LABEL_WARNING!>l@<!>{1}()
     1.((fun Int.() = 1))()
     1.(f())()
     1.if(true){f()}else{f()}()
diff --git a/compiler/testData/diagnostics/tests/LValueAssignment.kt b/compiler/testData/diagnostics/tests/LValueAssignment.kt
index b98be9fd2e9..f0d3683c545 100644
--- a/compiler/testData/diagnostics/tests/LValueAssignment.kt
+++ b/compiler/testData/diagnostics/tests/LValueAssignment.kt
@@ -78,17 +78,17 @@ class Test() {
         (f@ <!VARIABLE_EXPECTED!>getInt()<!>) += 343
 
         <!VARIABLE_EXPECTED!>1<!>++
-        (r@ <!VARIABLE_EXPECTED!>1<!>)++
+        (<!REDUNDANT_LABEL_WARNING!>r@<!> <!VARIABLE_EXPECTED!>1<!>)++
 
         <!VARIABLE_EXPECTED!>getInt()<!>++
-        (m@ <!VARIABLE_EXPECTED!>getInt()<!>)++
+        (<!REDUNDANT_LABEL_WARNING!>m@<!> <!VARIABLE_EXPECTED!>getInt()<!>)++
 
         this<!UNRESOLVED_REFERENCE!>++<!>
 
         var s : String = "r"
         s += "ss"
         s += this
-        s += (a@ 2)
+        s += (<!REDUNDANT_LABEL_WARNING!>a@<!> 2)
     }
 
     fun testIncompleteSyntax() {
@@ -106,7 +106,7 @@ class Test() {
         <!VAL_REASSIGNMENT!>b<!> += 34
 
         a++
-        (l@ a)++
+        (<!REDUNDANT_LABEL_WARNING!>l@<!> a)++
         <!UNUSED_CHANGED_VALUE!>(a)++<!>
     }
 
@@ -126,7 +126,7 @@ class Test() {
         ab.getArray()[54] = 23
         ab.getArray()[54]++
 
-        (f@ a)[3] = 4
+        (<!REDUNDANT_LABEL_WARNING!>f@<!> a)[3] = 4
 
         this<!NO_SET_METHOD!><!UNRESOLVED_REFERENCE!>[<!>54<!UNRESOLVED_REFERENCE!>]<!><!> = 34
     }
diff --git a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
index fe2e2ca4e0c..330b7c424fd 100644
--- a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
+++ b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
@@ -22,6 +22,6 @@ fun main(args : Array<String>) {
     <!NO_COMPANION_OBJECT!>System<!> is Int
     <!INVISIBLE_MEMBER!>System<!>()
     (<!NO_COMPANION_OBJECT!>System<!>)
-    foo@ <!NO_COMPANION_OBJECT!>System<!>
+    <!OI;REDUNDANT_LABEL_WARNING!>foo@<!> <!NO_COMPANION_OBJECT!>System<!>
     null in <!NO_COMPANION_OBJECT!>System<!>
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ReserveYield2.kt b/compiler/testData/diagnostics/tests/ReserveYield2.kt
index 165989407f9..b12cfbdba6a 100644
--- a/compiler/testData/diagnostics/tests/ReserveYield2.kt
+++ b/compiler/testData/diagnostics/tests/ReserveYield2.kt
@@ -5,8 +5,8 @@
 annotation class yield
 
 fun bar(p: Int) {
-    <!YIELD_IS_RESERVED!>yield<!>@ p
-    `yield`@ p
+    <!REDUNDANT_LABEL_WARNING!><!YIELD_IS_RESERVED!>yield<!>@<!> p
+    <!REDUNDANT_LABEL_WARNING!>`yield`@<!> p
 
     @<!YIELD_IS_RESERVED!>yield<!>() p
     @`yield`() p
diff --git a/compiler/testData/diagnostics/tests/Underscore.kt b/compiler/testData/diagnostics/tests/Underscore.kt
index 0b66374cec2..a67f76ab0e7 100644
--- a/compiler/testData/diagnostics/tests/Underscore.kt
+++ b/compiler/testData/diagnostics/tests/Underscore.kt
@@ -21,7 +21,7 @@ fun <!UNDERSCORE_IS_RESERVED!>__<!>(<!UNDERSCORE_IS_RESERVED!>___<!>: Int, y: <!
 
     fun localFun(<!UNDERSCORE_IS_RESERVED!>_<!>: String) = 1
 
-    <!UNDERSCORE_IS_RESERVED!>__<!>@ return if (y != null) <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>__<!>(<!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>____<!>, y) else <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>__<!>(`_`, <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>______<!>)
+    <!REDUNDANT_LABEL_WARNING!><!UNDERSCORE_IS_RESERVED!>__<!>@<!> return if (y != null) <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>__<!>(<!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>____<!>, y) else <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>__<!>(`_`, <!UNDERSCORE_USAGE_WITHOUT_BACKTICKS!>______<!>)
 }
 
 
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt
index 315b6b2b8fc..839d543d20b 100644
--- a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt
@@ -12,7 +12,7 @@ fun test2() {
     <!UNREACHABLE_CODE!>bar(<!>11, todo()/*comment1*/, <!UNREACHABLE_CODE!>""/*comment2*/)<!>
 }
 fun test3() {
-    <!UNREACHABLE_CODE!>bar(<!>11, l@(todo()/*comment*/), <!UNREACHABLE_CODE!>"")<!>
+    <!UNREACHABLE_CODE!>bar(<!>11, <!REDUNDANT_LABEL_WARNING!>l@<!>(todo()/*comment*/), <!UNREACHABLE_CODE!>"")<!>
 }
 
 fun todo(): Nothing = throw Exception()
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.kt
index 56af736b6d0..4e8bca9bdf7 100644
--- a/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.kt
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.kt
@@ -19,7 +19,7 @@ class TestObjectLiteral {
             val y = <!UNINITIALIZED_VARIABLE!>obj<!>
         }
     }
-    val obj1: A = l@ ( object: A(<!UNINITIALIZED_VARIABLE!>obj1<!>) {
+    val obj1: A = <!REDUNDANT_LABEL_WARNING!>l@<!> ( object: A(<!UNINITIALIZED_VARIABLE!>obj1<!>) {
         init {
             val x = <!UNINITIALIZED_VARIABLE!>obj1<!>
         }
diff --git a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.kt b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.kt
index ba4ec6da0e4..52d15ee4e69 100644
--- a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.kt
+++ b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.kt
@@ -51,12 +51,12 @@ fun testLoopLabelInReturn(xs: List<Int>) {
 }
 
 fun testValLabelInReturn() {
-    L@ val fn = { <!NOT_A_FUNCTION_LABEL!>return@L<!> }
+    <!REDUNDANT_LABEL_WARNING!>L@<!> val fn = { <!NOT_A_FUNCTION_LABEL!>return@L<!> }
     fn()
 }
 
 fun testHighOrderFunctionCallLabelInReturn() {
-    L@ run {
+    <!REDUNDANT_LABEL_WARNING!>L@<!> run {
         <!NOT_A_FUNCTION_LABEL!>return@L<!>
     }
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt
index 84714135a02..00a174f3a88 100644
--- a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt
+++ b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt
@@ -51,12 +51,12 @@ fun testLoopLabelInReturn(xs: List<Int>) {
 }
 
 fun testValLabelInReturn() {
-    L@ val fn = { <!NOT_A_FUNCTION_LABEL_WARNING!>return@L<!> }
+    <!REDUNDANT_LABEL_WARNING!>L@<!> val fn = { <!NOT_A_FUNCTION_LABEL_WARNING!>return@L<!> }
     fn()
 }
 
 fun testHighOrderFunctionCallLabelInReturn() {
-    L@ run {
+    <!REDUNDANT_LABEL_WARNING!>L@<!> run {
         <!NOT_A_FUNCTION_LABEL_WARNING!>return@L<!>
     }
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt
new file mode 100644
index 00000000000..06267698864
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt
@@ -0,0 +1,39 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann
+
+fun testLambdaLabel() = l@ { 42 }
+
+fun testAnonymousFunctionLabel() = l@ fun() {}
+
+fun testAnnotatedLambdaLabel() = lambda@ @Ann {}
+
+fun testParenthesizedLambdaLabel() = lambda@ ( {} )
+
+fun testLabelBoundToInvokeOperatorExpression() = <!REDUNDANT_LABEL_WARNING!>l@<!> { 42 }()
+
+fun testLabelBoundToLambda() = (l@ { 42 })()
+
+fun testWhileLoopLabel() {
+    L@ while (true) {}
+}
+
+fun testDoWhileLoopLabel() {
+    L@ do {} while (true)
+}
+
+fun testForLoopLabel(xs: List<Any>) {
+    L@ for (x in xs) {}
+}
+
+fun testValLabel() {
+    <!REDUNDANT_LABEL_WARNING!>L@<!> val fn = {}
+    fn()
+}
+
+fun testHighOrderFunctionCallLabel() {
+    <!REDUNDANT_LABEL_WARNING!>L@<!> run {}
+}
+
+fun testAnonymousObjectLabel() =
+    <!REDUNDANT_LABEL_WARNING!>L@<!> object {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.txt b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.txt
new file mode 100644
index 00000000000..61993b83ece
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.txt
@@ -0,0 +1,21 @@
+package
+
+public fun testAnnotatedLambdaLabel(): () -> kotlin.Unit
+public fun testAnonymousFunctionLabel(): () -> kotlin.Unit
+public fun testAnonymousObjectLabel(): kotlin.Any
+public fun testDoWhileLoopLabel(): kotlin.Unit
+public fun testForLoopLabel(/*0*/ xs: kotlin.collections.List<kotlin.Any>): kotlin.Unit
+public fun testHighOrderFunctionCallLabel(): kotlin.Unit
+public fun testLabelBoundToInvokeOperatorExpression(): kotlin.Int
+public fun testLabelBoundToLambda(): kotlin.Int
+public fun testLambdaLabel(): () -> kotlin.Int
+public fun testParenthesizedLambdaLabel(): () -> kotlin.Unit
+public fun testValLabel(): kotlin.Unit
+public fun testWhileLoopLabel(): kotlin.Unit
+
+@kotlin.annotation.Target(allowedTargets = {AnnotationTarget.EXPRESSION}) @kotlin.annotation.Retention(value = AnnotationRetention.SOURCE) public final annotation class Ann : kotlin.Annotation {
+    public constructor Ann()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.kt
index f8290772eae..e5b1e6b3584 100644
--- a/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.kt
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.kt
@@ -1,7 +1,7 @@
 import kotlin.reflect.KProperty
 
 class A3 {
-    val a: String by l@ MyProperty()
+    val a: String by <!REDUNDANT_LABEL_WARNING!>l@<!> MyProperty()
 
     class MyProperty<T> {}
 
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.kt b/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.kt
index fd48e57fb02..1d6225b7bc2 100644
--- a/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.kt
+++ b/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.kt
@@ -1,3 +1,3 @@
 fun test() {
-    (d@ <!DECLARATION_IN_ILLEGAL_CONTEXT!>val <!UNUSED_VARIABLE!>bar<!> = 2<!>)
+    (<!REDUNDANT_LABEL_WARNING!>d@<!> <!DECLARATION_IN_ILLEGAL_CONTEXT!>val <!UNUSED_VARIABLE!>bar<!> = 2<!>)
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.kt b/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.kt
index 8ab51d936e6..eedeedee207 100644
--- a/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.kt
+++ b/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.kt
@@ -5,19 +5,19 @@ package m
 
 fun test(i: Int?) {
     if (i != null) {
-        foo(l1@ <!DEBUG_INFO_SMARTCAST!>i<!>)
+        foo(<!OI;REDUNDANT_LABEL_WARNING!>l1@<!> <!DEBUG_INFO_SMARTCAST!>i<!>)
         foo((<!DEBUG_INFO_SMARTCAST!>i<!>))
-        foo(l2@ (<!DEBUG_INFO_SMARTCAST!>i<!>))
-        foo((l3@ <!DEBUG_INFO_SMARTCAST!>i<!>))
+        foo(<!OI;REDUNDANT_LABEL_WARNING!>l2@<!> (<!DEBUG_INFO_SMARTCAST!>i<!>))
+        foo((<!OI;REDUNDANT_LABEL_WARNING!>l3@<!> <!DEBUG_INFO_SMARTCAST!>i<!>))
     }
 
-    val a: Int = l4@ <!TYPE_MISMATCH!>""<!>
+    val a: Int = <!OI;REDUNDANT_LABEL_WARNING!>l4@<!> <!TYPE_MISMATCH!>""<!>
     val b: Int = (<!TYPE_MISMATCH!>""<!>)
     val c: Int = checkSubtype<Int>(<!TYPE_MISMATCH!>""<!>)
     val d: Int = <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, TYPE_MISMATCH!>checkSubtype<Long>(<!TYPE_MISMATCH!>""<!>)<!>
 
 
-    foo(l4@ <!TYPE_MISMATCH!>""<!>)
+    foo(<!OI;REDUNDANT_LABEL_WARNING!>l4@<!> <!TYPE_MISMATCH!>""<!>)
     foo((<!TYPE_MISMATCH!>""<!>))
     foo(checkSubtype<Int>(<!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, TYPE_MISMATCH!>""<!>))
     foo(<!NI;TYPE_MISMATCH, TYPE_MISMATCH!>checkSubtype<Long>(<!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, TYPE_MISMATCH!>""<!>)<!>)
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.kt b/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.kt
index e270df0ec1d..a9e8b9255bc 100644
--- a/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.kt
+++ b/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.kt
@@ -1,3 +1,3 @@
 fun f(s : String?) : Boolean {
-    return foo@(s?.equals("a"))!!
+    return <!REDUNDANT_LABEL_WARNING!>foo@<!>(s?.equals("a"))!!
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.kt
index 0bdaa750a1c..471612aaaf8 100644
--- a/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.kt
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.kt
@@ -11,7 +11,7 @@ fun <V> id(value: V) = value
 val par1 = (foo()) as String
 val par2 = ((foo())) as String
 
-val par3 = (dd@ (foo())) as String
+val par3 = (<!REDUNDANT_LABEL_WARNING!>dd@<!> (foo())) as String
 
 val par4 = ( @bar() (foo())) as String
 
diff --git a/compiler/testData/diagnostics/tests/inline/labeled.kt b/compiler/testData/diagnostics/tests/inline/labeled.kt
index 0599469f5e1..fa36e7540bd 100644
--- a/compiler/testData/diagnostics/tests/inline/labeled.kt
+++ b/compiler/testData/diagnostics/tests/inline/labeled.kt
@@ -24,17 +24,17 @@ inline fun foo(bar1: (String.() -> Int) -> Int, bar2: (()->Int) -> Int) {
 }
 
 inline fun foo2(bar1: (String.() -> Int) -> Int) {
-    l1@ <!USAGE_IS_NOT_INLINABLE!>bar1<!>
+    <!REDUNDANT_LABEL_WARNING!>l1@<!> <!USAGE_IS_NOT_INLINABLE!>bar1<!>
 
-    l2@ bar1 {
+    <!REDUNDANT_LABEL_WARNING!>l2@<!> bar1 {
         11
     }
 
-    (l3@ bar1) {
+    (<!REDUNDANT_LABEL_WARNING!>l3@<!> bar1) {
         11
     }
 
-    (l5@ (l4@ bar1)) {
+    (<!REDUNDANT_LABEL_WARNING!>l5@<!> (<!REDUNDANT_LABEL_WARNING!>l4@<!> bar1)) {
         11
     }
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/parenthesized.kt b/compiler/testData/diagnostics/tests/inline/parenthesized.kt
index a7423f6b5fc..046f9755a7f 100644
--- a/compiler/testData/diagnostics/tests/inline/parenthesized.kt
+++ b/compiler/testData/diagnostics/tests/inline/parenthesized.kt
@@ -22,6 +22,6 @@ inline fun inlineFunWithInvoke2(s: (p: Int) -> Unit) {
 }
 
 inline fun propagation(s: (p: Int) -> Unit) {
-    inlineFunWithInvoke((label@ s))
-    inlineFunWithInvoke((label2@ label@ s))
+    inlineFunWithInvoke((<!REDUNDANT_LABEL_WARNING!>label@<!> s))
+    inlineFunWithInvoke((<!REDUNDANT_LABEL_WARNING!>label2@<!> <!REDUNDANT_LABEL_WARNING!>label@<!> s))
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt b/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt
index e9fcaffc8dd..93b072acbf4 100644
--- a/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt
+++ b/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt
@@ -9,8 +9,8 @@ fun main(args : Array<String>) {
     val <!UNUSED_VARIABLE!>h<!> : String = <!TYPE_MISMATCH!>v--<!>;
     val <!UNUSED_VARIABLE!>h1<!> : String = <!TYPE_MISMATCH!>--v<!>;
     val <!UNUSED_VARIABLE!>i<!> : String = <!TYPE_MISMATCH!>!true<!>;
-    val <!UNUSED_VARIABLE!>j<!> : String = foo@ <!CONSTANT_EXPECTED_TYPE_MISMATCH!>true<!>;
-    val <!UNUSED_VARIABLE!>k<!> : String = foo@ bar@ <!CONSTANT_EXPECTED_TYPE_MISMATCH!>true<!>;
+    val <!UNUSED_VARIABLE!>j<!> : String = <!OI;REDUNDANT_LABEL_WARNING!>foo@<!> <!CONSTANT_EXPECTED_TYPE_MISMATCH!>true<!>;
+    val <!UNUSED_VARIABLE!>k<!> : String = <!OI;REDUNDANT_LABEL_WARNING!>foo@<!> <!OI;REDUNDANT_LABEL_WARNING!>bar@<!> <!CONSTANT_EXPECTED_TYPE_MISMATCH!>true<!>;
     val <!UNUSED_VARIABLE!>l<!> : String = <!TYPE_MISMATCH!>-1<!>;
     val <!UNUSED_VARIABLE!>m<!> : String = <!TYPE_MISMATCH!>+1<!>;
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.kt
index 1ffa3472243..aab2243f1d5 100644
--- a/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.kt
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.kt
@@ -14,7 +14,7 @@ fun test(bar: Bar, a: A) {
     // no elements with error types
     fooInt((bar()))
     fooInt(if (true) bar() else bar())
-    fooInt(label@ bar())
+    fooInt(<!REDUNDANT_LABEL_WARNING!>label@<!> bar())
     fooInt(a.bar())
-    fooInt(((label@ if (true) (a.bar()) else bar())))
+    fooInt(((<!REDUNDANT_LABEL_WARNING!>label@<!> if (true) (a.bar()) else bar())))
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.kt b/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.kt
index 1d3b5f73d77..1c8ae0da59f 100644
--- a/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.kt
+++ b/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.kt
@@ -1,23 +1,23 @@
 fun testEquals(x: Int) {
     if (<!SENSELESS_COMPARISON!>x == null<!>) {}
     if (<!SENSELESS_COMPARISON!>x == (null)<!>) {}
-    if (<!SENSELESS_COMPARISON!>x == foo@ null<!>) {}
+    if (<!SENSELESS_COMPARISON!>x == <!REDUNDANT_LABEL_WARNING!>foo@<!> null<!>) {}
 }
 
 fun testEqualsFlipped(x: Int) {
     if (<!SENSELESS_COMPARISON!>null == x<!>) {}
     if (<!SENSELESS_COMPARISON!>(null) == x<!>) {}
-    if (<!SENSELESS_COMPARISON!>foo@ null == x<!>) {}
+    if (<!SENSELESS_COMPARISON!><!REDUNDANT_LABEL_WARNING!>foo@<!> null == x<!>) {}
 }
 
 fun testNotEquals(x: Int) {
     if (<!SENSELESS_COMPARISON!>x != null<!>) {}
     if (<!SENSELESS_COMPARISON!>x != (null)<!>) {}
-    if (<!SENSELESS_COMPARISON!>x != foo@ null<!>) {}
+    if (<!SENSELESS_COMPARISON!>x != <!REDUNDANT_LABEL_WARNING!>foo@<!> null<!>) {}
 }
 
 fun testNotEqualsFlipped(x: Int) {
     if (<!SENSELESS_COMPARISON!>null != x<!>) {}
     if (<!SENSELESS_COMPARISON!>(null) != x<!>) {}
-    if (<!SENSELESS_COMPARISON!>foo@ null != x<!>) {}
+    if (<!SENSELESS_COMPARISON!><!REDUNDANT_LABEL_WARNING!>foo@<!> null != x<!>) {}
 }
\ No newline at end of file
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index a87f8812a62..0484606d77c 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -4140,6 +4140,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt");
             }
 
+            @TestMetadata("redundantLabel.kt")
+            public void testRedundantLabel() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt");
+            }
+
             @TestMetadata("specialConstructsAndPlatformTypes.kt")
             public void testSpecialConstructsAndPlatformTypes() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/controlStructures/specialConstructsAndPlatformTypes.kt");
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
index d4fff9f78be..df63df64a4d 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
@@ -4140,6 +4140,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.kt");
             }
 
+            @TestMetadata("redundantLabel.kt")
+            public void testRedundantLabel() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/controlStructures/redundantLabel.kt");
+            }
+
             @TestMetadata("specialConstructsAndPlatformTypes.kt")
             public void testSpecialConstructsAndPlatformTypes() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/controlStructures/specialConstructsAndPlatformTypes.kt");