[FIR] Forbid multiple labels per statement

^KT-53629: Fixed

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -4957,6 +4957,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.MULTIPLE_LABELS_ARE_FORBIDDEN) { firDiagnostic ->
+        MultipleLabelsAreForbiddenImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.DEPRECATED_ACCESS_TO_ENUM_ENTRY_COMPANION_PROPERTY) { firDiagnostic ->
         DeprecatedAccessToEnumEntryCompanionPropertyImpl(
             firDiagnostic as KtPsiDiagnostic,

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -3450,6 +3450,10 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = RedundantLabelWarning::class
     }
 
+    interface MultipleLabelsAreForbidden : KtFirDiagnostic<KtLabelReferenceExpression> {
+        override val diagnosticClass get() = MultipleLabelsAreForbidden::class
+    }
+
     interface DeprecatedAccessToEnumEntryCompanionProperty : KtFirDiagnostic<PsiElement> {
         override val diagnosticClass get() = DeprecatedAccessToEnumEntryCompanionProperty::class
     }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -4161,6 +4161,11 @@ internal class RedundantLabelWarningImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<KtLabelReferenceExpression>(firDiagnostic, token), KtFirDiagnostic.RedundantLabelWarning
 
+internal class MultipleLabelsAreForbiddenImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtLabelReferenceExpression>(firDiagnostic, token), KtFirDiagnostic.MultipleLabelsAreForbidden
+
 internal class DeprecatedAccessToEnumEntryCompanionPropertyImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -23901,6 +23901,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
             public void testLabelsMustBeNamed() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.kt");
             }
+
+            @Test
+            @TestMetadata("multipleLabels.kt")
+            public void testMultipleLabels() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/labels/multipleLabels.kt");
+            }
         }
 
         @Nested

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -23901,6 +23901,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
             public void testLabelsMustBeNamed() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.kt");
             }
+
+            @Test
+            @TestMetadata("multipleLabels.kt")
+            public void testMultipleLabels() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/labels/multipleLabels.kt");
+            }
         }
 
         @Nested

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java

@@ -23895,6 +23895,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             public void testLabelsMustBeNamed() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.kt");
             }
+
+            @Test
+            @TestMetadata("multipleLabels.kt")
+            public void testMultipleLabels() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/labels/multipleLabels.kt");
+            }
         }
 
         @Nested

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java

@@ -23901,6 +23901,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             public void testLabelsMustBeNamed() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.kt");
             }
+
+            @Test
+            @TestMetadata("multipleLabels.kt")
+            public void testMultipleLabels() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/labels/multipleLabels.kt");
+            }
         }
 
         @Nested

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -1751,6 +1751,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
 
     val LABEL by object : DiagnosticGroup("label") {
         val REDUNDANT_LABEL_WARNING by warning<KtLabelReferenceExpression>(PositioningStrategy.LABEL)
+        val MULTIPLE_LABELS_ARE_FORBIDDEN by error<KtLabelReferenceExpression>(PositioningStrategy.LABEL)
     }
 
     val ENUM_ENTRIES_DEPRECATIONS by object : DiagnosticGroup("Enum.entries resolve deprecations") {

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -872,6 +872,7 @@ object FirErrors {
 
     // label
     val REDUNDANT_LABEL_WARNING: KtDiagnosticFactory0 by warning0<KtLabelReferenceExpression>(SourceElementPositioningStrategies.LABEL)
+    val MULTIPLE_LABELS_ARE_FORBIDDEN: KtDiagnosticFactory0 by error0<KtLabelReferenceExpression>(SourceElementPositioningStrategies.LABEL)
 
     // Enum.entries resolve deprecations
     val DEPRECATED_ACCESS_TO_ENUM_ENTRY_COMPANION_PROPERTY: KtDiagnosticFactory0 by warning0<PsiElement>()

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt

@@ -572,6 +572,7 @@ val FIR_NON_SUPPRESSIBLE_ERROR_NAMES: Set<String> = setOf(
     "RETURN_FOR_BUILT_IN_SUSPEND",
     "MIXING_SUSPEND_AND_NON_SUSPEND_SUPERTYPES",
     "MIXING_FUNCTIONAL_KINDS_IN_SUPERTYPES",
+    "MULTIPLE_LABELS_ARE_FORBIDDEN",
     "INCOMPATIBLE_CLASS",
     "PRE_RELEASE_CLASS",
     "IR_WITH_UNSTABLE_ABI_COMPILED_CLASS",

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt

@@ -501,6 +501,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PACKAGE_CANNOT_BE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PACKAGE_OR_CLASSIFIER_REDECLARATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PLATFORM_CLASS_MAPPED_TO_KOTLIN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.COMPILER_REQUIRED_ANNOTATION_AMBIGUITY
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_LABELS_ARE_FORBIDDEN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_AND_ACTUAL_IN_THE_SAME_MODULE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.POTENTIALLY_NON_REPORTED_ANNOTATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRE_RELEASE_CLASS
@@ -2538,6 +2539,8 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
             "Label is redundant, because it cannot be referenced in a 'break', 'continue', or 'return' expression."
         )
 
+        map.put(MULTIPLE_LABELS_ARE_FORBIDDEN, "Multiple labels per statement are forbidden.")
+
         // Enum entries deprecations
         map.put(
             DEPRECATED_ACCESS_TO_ENUM_ENTRY_COMPANION_PROPERTY,

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt

@@ -194,6 +194,7 @@ private fun ConeDiagnostic.toKtDiagnostic(
     is ConeAmbiguousFunctionTypeKinds -> FirErrors.AMBIGUOUS_FUNCTION_TYPE_KIND.createOn(source, kinds)
     is ConeUnsupportedClassLiteralsWithEmptyLhs -> FirErrors.UNSUPPORTED_CLASS_LITERALS_WITH_EMPTY_LHS.createOn(source)
     is ConeMissingConstructorKeyword -> FirErrors.MISSING_CONSTRUCTOR_KEYWORD.createOn(source)
+    is ConeMultipleLabelsAreForbidden -> FirErrors.MULTIPLE_LABELS_ARE_FORBIDDEN.createOn(this.source)
     else -> throw IllegalArgumentException("Unsupported diagnostic type: ${this.javaClass}")
 }
 

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/LightTreeRawFirExpressionBuilder.kt

@@ -397,19 +397,19 @@ class LightTreeRawFirExpressionBuilder(
      */
     private fun convertLabeledExpression(labeledExpression: LighterASTNode): FirElement {
         var firExpression: FirElement? = null
-        var errorLabelSource: KtSourceElement? = null
+        var labelSource: KtSourceElement? = null
+        var forbiddenLabelKind: ForbiddenLabelKind? = null
+
+        val isRepetitiveLabel = labeledExpression.getLabeledExpression()?.tokenType == LABELED_EXPRESSION
 
         labeledExpression.forEachChildren {
             context.setNewLabelUserNode(it)
             when (it.tokenType) {
                 LABEL_QUALIFIER -> {
-                    val rawName = it.toString()
+                    val name = it.asText.dropLast(1)
-                    val pair = buildLabelAndErrorSource(
+                    labelSource = it.getChildNodesByType(LABEL).single().toFirSourceElement()
-                        rawName.substring(0, rawName.length - 1),
+                    context.addNewLabel(buildLabel(name, labelSource!!))
-                        it.getChildNodesByType(LABEL).single().toFirSourceElement()
+                    forbiddenLabelKind = getForbiddenLabelKind(name, isRepetitiveLabel)
-                    )
-                    context.addNewLabel(pair.first)
-                    errorLabelSource = pair.second
                 }
                 BLOCK -> firExpression = declarationBuilder.convertBlock(it)
                 PROPERTY -> firExpression = declarationBuilder.convertPropertyDeclaration(it)
@@ -419,7 +419,7 @@ class LightTreeRawFirExpressionBuilder(
 
         context.dropLastLabel()
 
-        return buildExpressionWithErrorLabel(firExpression, errorLabelSource, labeledExpression.toFirSourceElement())
+        return buildExpressionHandlingErrors(firExpression, labeledExpression.toFirSourceElement(), forbiddenLabelKind, labelSource)
     }
 
     /**

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/PsiRawFirBuilder.kt

@@ -51,7 +51,10 @@ import org.jetbrains.kotlin.types.ConstantValueKind
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.types.expressions.OperatorConventions
 import org.jetbrains.kotlin.util.OperatorNameConventions
-import org.jetbrains.kotlin.utils.addToStdlib.*
+import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
+import org.jetbrains.kotlin.utils.addToStdlib.runUnless
+import org.jetbrains.kotlin.utils.addToStdlib.shouldNotBeCalled
 import org.jetbrains.kotlin.utils.exceptions.errorWithAttachment
 import org.jetbrains.kotlin.utils.exceptions.requireWithAttachment
 import org.jetbrains.kotlin.utils.exceptions.withPsiEntry
@@ -3135,20 +3138,24 @@ open class PsiRawFirBuilder(
 
         override fun visitLabeledExpression(expression: KtLabeledExpression, data: FirElement?): FirElement {
             val label = expression.getTargetLabel()
-            var errorLabelSource: KtSourceElement? = null
+            var labelSource: KtSourceElement? = null
+            var forbiddenLabelKind: ForbiddenLabelKind? = null
+
+            val isRepetitiveLabel = expression.baseExpression is KtLabeledExpression
 
             val result = if (label != null) {
-                val rawName = label.getReferencedNameElement().node!!.text
+                val name = label.getReferencedNameElement().node!!.text
-                val labelAndErrorSource = buildLabelAndErrorSource(rawName, label.toKtPsiSourceElement())
+                forbiddenLabelKind = getForbiddenLabelKind(name, isRepetitiveLabel)
-                errorLabelSource = labelAndErrorSource.second
+                labelSource = label.toKtPsiSourceElement()
-                context.withNewLabel(labelAndErrorSource.first, expression.baseExpression) {
+                val firLabel = buildLabel(name, labelSource)
+                context.withNewLabel(firLabel, expression.baseExpression) {
                     expression.baseExpression?.accept(this, data)
                 }
             } else {
                 expression.baseExpression?.accept(this, data)
             }
 
-            return buildExpressionWithErrorLabel(result, errorLabelSource, expression.toFirSourceElement())
+            return buildExpressionHandlingErrors(result, expression.toFirSourceElement(), forbiddenLabelKind, labelSource)
         }
 
         override fun visitAnnotatedExpression(expression: KtAnnotatedExpression, data: FirElement?): FirElement {

compiler/fir/raw-fir/raw-fir.common/src/org/jetbrains/kotlin/fir/builder/AbstractRawFirBuilder.kt

@@ -1044,26 +1044,41 @@ abstract class AbstractRawFirBuilder<T>(val baseSession: FirSession, val context
         initContainingClassAttr(context)
     }
 
-    protected fun buildLabelAndErrorSource(rawName: String, source: KtSourceElement): Pair<FirLabel, KtSourceElement?> {
+    protected fun buildLabel(rawName: String, source: KtSourceElement): FirLabel {
         val firLabel = buildLabel {
             name = KtPsiUtil.unquoteIdentifier(rawName)
             this.source = source
         }
 
-        return Pair(firLabel, if (rawName.isUnderscore) firLabel.source else null)
+        return firLabel
     }
 
-    protected fun buildExpressionWithErrorLabel(
+    protected fun getForbiddenLabelKind(rawName: String, isMultipleLabel: Boolean): ForbiddenLabelKind? = when {
+        rawName.isUnderscore -> ForbiddenLabelKind.UNDERSCORE_IS_RESERVED
+        isMultipleLabel -> ForbiddenLabelKind.MULTIPLE_LABEL
+        else -> null
+    }
+
+    protected enum class ForbiddenLabelKind {
+        UNDERSCORE_IS_RESERVED, MULTIPLE_LABEL
+    }
+
+    protected fun buildExpressionHandlingErrors(
         element: FirElement?,
-        errorLabelSource: KtSourceElement?,
         elementSource: KtSourceElement,
+        forbiddenLabelKind: ForbiddenLabelKind?,
+        forbiddenLabelSource: KtSourceElement?,
     ): FirElement {
         return if (element != null) {
-            if (errorLabelSource != null) {
+            if (forbiddenLabelKind != null) {
+                require(forbiddenLabelSource != null)
                 buildErrorExpression {
                     this.source = element.source
                     this.expression = element as? FirExpression
-                    diagnostic = ConeUnderscoreIsReserved(errorLabelSource)
+                    diagnostic = when (forbiddenLabelKind) {
+                        ForbiddenLabelKind.UNDERSCORE_IS_RESERVED -> ConeUnderscoreIsReserved(forbiddenLabelSource)
+                        ForbiddenLabelKind.MULTIPLE_LABEL -> ConeMultipleLabelsAreForbidden(forbiddenLabelSource)
+                    }
                 }
             } else {
                 element

compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt

@@ -27,6 +27,10 @@ class ConeUnderscoreIsReserved(source: KtSourceElement) : ConeDiagnosticWithSour
     override val reason: String get() = "Names _, __, ___, ..., are reserved in Kotlin"
 }
 
+class ConeMultipleLabelsAreForbidden(source: KtSourceElement) : ConeDiagnosticWithSource(source) {
+    override val reason: String get() = "Multiple labels per statement are forbidden"
+}
+
 class ConeCannotInferTypeParameterType(
     val typeParameter: FirTypeParameterSymbol,
     override val reason: String = "Cannot infer type for parameter ${typeParameter.name}"

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirExpressionUtil.kt

@@ -102,7 +102,7 @@ fun <T : FirStatement> FirBlock.replaceFirstStatement(factory: (T) -> FirStateme
 }
 
 fun FirExpression.unwrapErrorExpression(): FirExpression? =
-    if (this is FirErrorExpression) expression?.run { unwrapErrorExpression() } else this
+    if (this is FirErrorExpression) expression?.unwrapErrorExpression() else this
 
 fun FirExpression.unwrapArgument(): FirExpression = (this as? FirWrappedArgumentExpression)?.expression ?: this
 

compiler/testData/diagnostics/tests/controlStructures/nestedLoopsWithMultipleLabels.fir.kt

@@ -0,0 +1,10 @@
+// K2: See KT-65342
+
+fun test() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>a@<!> b@ while(true) {
+        val f = {
+            return@a
+        }
+        break@b
+    }
+}

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

@@ -1,4 +1,5 @@
-// FIR_IDENTICAL
+// K2: See KT-65342
+
 fun test() {
     a@ b@ while(true) {
         val f = {

compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.fir.kt

@@ -30,12 +30,12 @@ fun testAnnotatedLambdaLabel() =
     }
 
 fun testLambdaMultipleLabels1() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         <!NOT_A_FUNCTION_LABEL!>return@lambda1<!>
     }
 
 fun testLambdaMultipleLabels2() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         return@lambda2
     }
 
@@ -62,7 +62,7 @@ fun testHighOrderFunctionCallLabelInReturn() {
 }
 
 fun testMultipleLabelsWithNestedLambda() {
-    l1@ l2@{
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l1@<!> l2@{
         {
             <!NOT_A_FUNCTION_LABEL!>return@l1<!>
         }

compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.fir.kt

@@ -30,12 +30,12 @@ fun testAnnotatedLambdaLabel() =
     }
 
 fun testLambdaMultipleLabels1() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         <!NOT_A_FUNCTION_LABEL!>return@lambda1<!>
     }
 
 fun testLambdaMultipleLabels2() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         return@lambda2
     }
 
@@ -62,7 +62,7 @@ fun testHighOrderFunctionCallLabelInReturn() {
 }
 
 fun testMultipleLabelsWithNestedLambda() {
-    l1@ l2@{
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l1@<!> l2@{
         {
             <!NOT_A_FUNCTION_LABEL!>return@l1<!>
         }

compiler/testData/diagnostics/tests/inline/labelsAndNonInlineUsage.fir.kt

@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED -MULTIPLE_LABELS_ARE_FORBIDDEN
 
 // See KT-65337
 // !DIAGNOSTICS: -UNRESOLVED_REFERENCE

compiler/testData/diagnostics/tests/inline/labelsAndNonInlineUsage.kt

@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED -MULTIPLE_LABELS_ARE_FORBIDDEN
 
 // See KT-65337
 // !DIAGNOSTICS: -UNRESOLVED_REFERENCE

compiler/testData/diagnostics/tests/inline/parenthesized.fir.kt

@@ -23,5 +23,5 @@ inline fun inlineFunWithInvoke2(s: (p: Int) -> Unit) {
 
 inline fun propagation(s: (p: Int) -> Unit) {
     inlineFunWithInvoke((label@ s))
-    inlineFunWithInvoke((label2@ label@ s))
+    inlineFunWithInvoke((<!MULTIPLE_LABELS_ARE_FORBIDDEN!>label2@<!> label@ s))
 }

compiler/testData/diagnostics/tests/labels/multipleLabels.fir.kt

@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING
+
+fun foo1() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+    } while (true)
+}
+
+fun foo2() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l4@<!> <!UNDERSCORE_IS_RESERVED!>_<!>@ <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l3@<!> <!UNDERSCORE_IS_RESERVED!>__<!>@ <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ while (true) {
+    }
+}
+
+fun foo3() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ 42
+}
+
+fun foo4() {
+    l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo5() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo6() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+        l4@ l3@{ true }
+    } while (true)
+}
+
+fun foo7() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l3@<!> <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ fun bar() {}
+}

compiler/testData/diagnostics/tests/labels/multipleLabels.kt

@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING
+
+fun foo1() {
+    l2@ l1@ do {
+    } while (true)
+}
+
+fun foo2() {
+    l4@ <!UNDERSCORE_IS_RESERVED!>_<!>@ l3@ <!UNDERSCORE_IS_RESERVED!>__<!>@ l2@ l1@ while (true) {
+    }
+}
+
+fun foo3() {
+    l2@ l1@ 42
+}
+
+fun foo4() {
+    l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo5() {
+    l2@ l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo6() {
+    l2@ l1@ do {
+        l4@ l3@{ true }
+    } while (true)
+}
+
+fun foo7() {
+    l3@ l2@ l1@ fun bar() {}
+}

compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.fir.kt

@@ -1,3 +1,5 @@
+// K2: See KT-65342
+
 fun main() {
     val a : Int? = null;
     var v = 1
@@ -9,7 +11,7 @@ fun main() {
     val h1 : String = <!INITIALIZER_TYPE_MISMATCH!>--v<!>;
     val i : String = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>!true<!>;
     val j : String = <!INITIALIZER_TYPE_MISMATCH!>foo@ true<!>;
-    val k : String = <!INITIALIZER_TYPE_MISMATCH!>foo@ bar@ true<!>;
+    val k : String = <!MULTIPLE_LABELS_ARE_FORBIDDEN!>foo@<!> bar@ true;
     val l : String = <!INITIALIZER_TYPE_MISMATCH!>-1<!>;
     val m : String = <!INITIALIZER_TYPE_MISMATCH!>+1<!>;
 }

compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt

@@ -1,3 +1,5 @@
+// K2: See KT-65342
+
 fun main() {
     val a : Int? = null;
     var v = 1

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -23901,6 +23901,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             public void testLabelsMustBeNamed() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.kt");
             }
+
+            @Test
+            @TestMetadata("multipleLabels.kt")
+            public void testMultipleLabels() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/labels/multipleLabels.kt");
+            }
         }
 
         @Nested