[FIR] Fix local variable tests.

- Mangle names for extension receivers in lambdas
 - Correctly mark anonymous variables and variables for arguments
   for destructuring declaration.

There is one failure remaining which is cause by lambda
type inference differences that leads to FIR having an explicit
return from the lambda whereas old frontend leads to an implicit
return. This difference is visible in debug stepping that the
local variables tests do because the implicit return has the line
number of the closing brace of the lambda. This change adds an
IrText test to make the difference clear.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/ConversionUtils.kt

@@ -55,12 +55,15 @@ import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrErrorTypeImpl
 import org.jetbrains.kotlin.ir.util.SymbolTable
 import org.jetbrains.kotlin.ir.util.functions
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.psi
+import org.jetbrains.kotlin.psi.KtParameter
 import org.jetbrains.kotlin.psi.KtQualifiedExpression
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffsetSkippingComments
+import org.jetbrains.kotlin.resolve.calls.util.isSingleUnderscore
 import org.jetbrains.kotlin.types.ConstantValueKind
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.util.OperatorNameConventions
@@ -488,16 +491,18 @@ internal fun IrDeclarationParent.declareThisReceiverParameter(
     thisType: IrType,
     thisOrigin: IrDeclarationOrigin,
     startOffset: Int = this.startOffset,
-    endOffset: Int = this.endOffset
+    endOffset: Int = this.endOffset,
-): IrValueParameter =
+    name: Name = SpecialNames.THIS
-    symbolTable.irFactory.createValueParameter(
+): IrValueParameter {
+    return symbolTable.irFactory.createValueParameter(
         startOffset, endOffset, thisOrigin, IrValueParameterSymbolImpl(),
-        SpecialNames.THIS, UNDEFINED_PARAMETER_INDEX, thisType,
+        name, UNDEFINED_PARAMETER_INDEX, thisType,
         varargElementType = null, isCrossinline = false, isNoinline = false,
         isHidden = false, isAssignable = false
     ).apply {
         this.parent = this@declareThisReceiverParameter
     }
+}
 
 fun FirClass.irOrigin(firProvider: FirProvider): IrDeclarationOrigin = when {
     firProvider.getFirClassifierContainerFileIfAny(symbol) != null -> IrDeclarationOrigin.DEFINED
@@ -615,6 +620,15 @@ fun FirSession.createFilesWithGeneratedDeclarations(): List<FirFile> {
 fun FirDeclaration?.computeIrOrigin(predefinedOrigin: IrDeclarationOrigin? = null): IrDeclarationOrigin {
     return predefinedOrigin
         ?: (this?.origin as? FirDeclarationOrigin.Plugin)?.let { IrPluginDeclarationOrigin(it.key) }
+        ?: ((this as? FirValueParameter)?.source.psi as? KtParameter)?.let {
+            if (it.isSingleUnderscore) {
+                IrDeclarationOrigin.UNDERSCORE_PARAMETER
+            } else if (it.destructuringDeclaration != null) {
+                IrDeclarationOrigin.DESTRUCTURED_OBJECT_PARAMETER
+            } else {
+                null
+            }
+        }
         ?: IrDeclarationOrigin.DEFINED
 }
 

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -338,12 +338,17 @@ class Fir2IrDeclarationStorage(
                     else parentPropertyReceiverType
                 if (receiverTypeRef != null) {
                     extensionReceiverParameter = receiverTypeRef.convertWithOffsets { startOffset, endOffset ->
+                        val name = (function as? FirAnonymousFunction)?.label?.name?.let {
+                            val suffix = it.takeIf(Name::isValidIdentifier) ?: "\$receiver"
+                            Name.identifier("\$this\$$suffix")
+                        } ?: SpecialNames.THIS
                         declareThisReceiverParameter(
                             symbolTable,
                             thisType = receiverTypeRef.toIrType(typeContext),
                             thisOrigin = thisOrigin,
                             startOffset = startOffset,
-                            endOffset = endOffset
+                            endOffset = endOffset,
+                            name = name
                         )
                     }
                 }

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/Fir2IrTextTestGenerated.java

@@ -2462,6 +2462,12 @@ public class Fir2IrTextTestGenerated extends AbstractFir2IrTextTest {
             runTest("compiler/testData/ir/irText/lambdas/justLambda.kt");
         }
 
+        @Test
+        @TestMetadata("lambdaReturningUnit.kt")
+        public void testLambdaReturningUnit() throws Exception {
+            runTest("compiler/testData/ir/irText/lambdas/lambdaReturningUnit.kt");
+        }
+
         @Test
         @TestMetadata("localFunction.kt")
         public void testLocalFunction() throws Exception {

compiler/testData/codegen/box/fir/noSymbolForIntRangeIterator.fir.ir.txt

@@ -69,7 +69,7 @@ FILE fqName:<root> fileName:/noSymbolForIntRangeIterator.kt
                     CALL 'public final fun buildString (builderAction: @[ExtensionFunctionType] kotlin.Function1<java.lang.StringBuilder, kotlin.Unit>): kotlin.String [inline] declared in kotlin.text.StringsKt' type=kotlin.String origin=null
                       builderAction: FUN_EXPR type=kotlin.Function1<java.lang.StringBuilder, kotlin.Unit> origin=LAMBDA
                         FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:java.lang.StringBuilder) returnType:kotlin.Unit
-                          $receiver: VALUE_PARAMETER name:<this> type:java.lang.StringBuilder
+                          $receiver: VALUE_PARAMETER name:$this$buildString type:java.lang.StringBuilder
                           BLOCK_BODY
                             BLOCK type=kotlin.Unit origin=FOR_LOOP
                               VAR FOR_LOOP_ITERATOR name:tmp_2 type:kotlin.collections.IntIterator [val]
@@ -85,7 +85,7 @@ FILE fqName:<root> fileName:/noSymbolForIntRangeIterator.kt
                                     CALL 'public final fun next (): kotlin.Int [operator] declared in kotlin.collections.IntIterator' type=kotlin.Int origin=FOR_LOOP_NEXT
                                       $this: GET_VAR 'val tmp_2: kotlin.collections.IntIterator [val] declared in <root>.test.localFunc.<anonymous>' type=kotlin.collections.IntIterator origin=null
                                   CALL 'public final fun appendLine (value: kotlin.String?): java.lang.StringBuilder [inline] declared in kotlin.text.StringsKt' type=java.lang.StringBuilder origin=null
-                                    $receiver: GET_VAR '<this>: java.lang.StringBuilder declared in <root>.test.localFunc.<anonymous>' type=java.lang.StringBuilder origin=null
+                                    $receiver: GET_VAR '$this$buildString: java.lang.StringBuilder declared in <root>.test.localFunc.<anonymous>' type=java.lang.StringBuilder origin=null
                                     value: STRING_CONCATENATION type=kotlin.String
                                       CALL 'public final fun times (other: kotlin.Int): kotlin.Int [operator] declared in kotlin.Int' type=kotlin.Int origin=MUL
                                         $this: GET_VAR 'val i: kotlin.Int [val] declared in <root>.test.localFunc' type=kotlin.Int origin=null

compiler/testData/debug/localVariables/suspend/mergeLvt.kt

@@ -41,7 +41,9 @@ suspend fun box() {
 // test.kt:16 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int, $this$extensionFun$iv$iv:AtomicInt=AtomicInt, $i$f$extensionFun:int=0:int
 // test.kt:20 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int
 // test.kt:21 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int, $i$a$-suspendCoroutineUninterceptedOrReturn-TestKt$suspendBar$2$iv:int=0:int
+// EXPECTATIONS CLASSIC_FRONTEND
 // test.kt:22 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int, $i$a$-suspendCoroutineUninterceptedOrReturn-TestKt$suspendBar$2$iv:int=0:int
+// EXPECTATIONS
 // test.kt:20 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int
 // test.kt:23 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null, $i$f$suspendBar:int=0:int
 // test.kt:26 box: $continuation:kotlin.coroutines.Continuation=TestKt$box$1, $result:java.lang.Object=null

compiler/testData/ir/irText/classes/initValInLambda.fir.ir.txt

@@ -22,7 +22,7 @@ FILE fqName:<root> fileName:/initValInLambda.kt
           $receiver: CONST Int type=kotlin.Int value=1
           block: FUN_EXPR type=kotlin.Function1<kotlin.Int, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:kotlin.Int) returnType:kotlin.Unit
-              $receiver: VALUE_PARAMETER name:<this> type:kotlin.Int
+              $receiver: VALUE_PARAMETER name:$this$run type:kotlin.Int
               BLOCK_BODY
                 SET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:x type:kotlin.Int visibility:private [final]' type=kotlin.Unit origin=null
                   receiver: GET_VAR '<this>: <root>.TestInitValInLambdaCalledOnce declared in <root>.TestInitValInLambdaCalledOnce' type=<root>.TestInitValInLambdaCalledOnce origin=null

compiler/testData/ir/irText/expressions/kt37570.fir.ir.txt

@@ -26,11 +26,11 @@ FILE fqName:<root> fileName:/kt37570.kt
             $receiver: CALL 'public final fun a (): kotlin.String declared in <root>' type=kotlin.String origin=null
             block: FUN_EXPR type=kotlin.Function1<kotlin.String, kotlin.Unit> origin=LAMBDA
               FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:kotlin.String) returnType:kotlin.Unit
-                $receiver: VALUE_PARAMETER name:<this> type:kotlin.String
+                $receiver: VALUE_PARAMETER name:$this$apply type:kotlin.String
                 BLOCK_BODY
                   SET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:b type:kotlin.String visibility:private [final]' type=kotlin.Unit origin=null
                     receiver: GET_VAR '<this>: <root>.A declared in <root>.A' type=<root>.A origin=null
-                    value: GET_VAR '<this>: kotlin.String declared in <root>.A.<anonymous>' type=kotlin.String origin=null
+                    value: GET_VAR '$this$apply: kotlin.String declared in <root>.A.<anonymous>' type=kotlin.String origin=null
     FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
       overridden:
         public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any

compiler/testData/ir/irText/expressions/kt37570.fir.kt.txt

@@ -14,9 +14,10 @@ class A {
 
   init {
     a().apply<String>(block = local fun String.<anonymous>() {
-      <this>.#b = <this>
+      <this>.#b = $this$apply
     }
 ) /*~> Unit */
   }
 
 }
+

compiler/testData/ir/irText/expressions/kt47082.fir.ir.txt

@@ -74,14 +74,14 @@ FILE fqName:<root> fileName:/kt47082.kt
           <E>: R of <root>.foo
           block: FUN_EXPR type=kotlin.Function1<<root>.Derived<IrErrorType(null)>, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.Derived<IrErrorType(null)>) returnType:kotlin.Unit
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.Derived<IrErrorType(null)>
+              $receiver: VALUE_PARAMETER name:$this$produce type:<root>.Derived<IrErrorType(null)>
               BLOCK_BODY
                 TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                   CALL 'public final fun toChannel <E, C> (destination: C of <root>.toChannel): C of <root>.toChannel declared in <root>' type=<root>.Derived<IrErrorType(null)> origin=null
                     <E>: R of <root>.foo
                     <C>: <root>.Derived<IrErrorType(null)>
                     $receiver: GET_VAR 'r: <root>.Receiver<R of <root>.foo> declared in <root>.foo' type=<root>.Receiver<R of <root>.foo> origin=null
-                    destination: GET_VAR '<this>: <root>.Derived<IrErrorType(null)> declared in <root>.foo.<anonymous>' type=<root>.Derived<IrErrorType(null)> origin=null
+                    destination: GET_VAR '$this$produce: <root>.Derived<IrErrorType(null)> declared in <root>.foo.<anonymous>' type=<root>.Derived<IrErrorType(null)> origin=null
   FUN name:box visibility:public modality:FINAL <> () returnType:kotlin.String
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='public final fun box (): kotlin.String declared in <root>'

compiler/testData/ir/irText/expressions/kt47082.fir.kt.txt

@@ -20,7 +20,7 @@ fun <E : Any?, C : Base<E>> Receiver<E>.toChannel(destination: C): C {
 
 fun <R : Any?> foo(r: Receiver<R>): R {
   return produce<R>(block = local fun Derived<ErrorType>.<anonymous>() {
-    r.toChannel<R, Derived<ErrorType>>(destination = <this>) /*~> Unit */
+    r.toChannel<R, Derived<ErrorType>>(destination = $this$produce) /*~> Unit */
   }
 )
 }
@@ -28,3 +28,4 @@ fun <R : Any?> foo(r: Receiver<R>): R {
 fun box(): String {
   return "OK"
 }
+

compiler/testData/ir/irText/firProblems/AllCandidates.fir.ir.txt

@@ -61,10 +61,10 @@ FILE fqName:<root> fileName:/AllCandidates.kt
             <R>: @[FlexibleNullability] A of <root>.allCandidatesResult?
           block: FUN_EXPR type=kotlin.Function1<@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?) returnType:kotlin.Unit
-              $receiver: VALUE_PARAMETER name:<this> type:@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?
+              $receiver: VALUE_PARAMETER name:$this$apply type:@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?
               BLOCK_BODY
                 CALL 'public open fun setAllCandidates (allCandidates: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] <root>.ResolvedCall<@[FlexibleNullability] D of <root>.OverloadResolutionResultsImpl?>?>?): kotlin.Unit declared in <root>.OverloadResolutionResultsImpl' type=kotlin.Unit origin=EQ
-                  $this: GET_VAR '<this>: @[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? declared in <root>.allCandidatesResult.<anonymous>' type=@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? origin=null
+                  $this: GET_VAR '$this$apply: @[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? declared in <root>.allCandidatesResult.<anonymous>' type=@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? origin=null
                   allCandidates: CALL 'public final fun map <T, R> (transform: kotlin.Function1<T of kotlin.collections.CollectionsKt.map, R of kotlin.collections.CollectionsKt.map>): kotlin.collections.List<R of kotlin.collections.CollectionsKt.map> [inline] declared in kotlin.collections.CollectionsKt' type=kotlin.collections.List<<root>.ResolvedCall<A of <root>.allCandidatesResult>> origin=null
                     <T>: <root>.MyCandidate
                     <R>: <root>.ResolvedCall<A of <root>.allCandidatesResult>

compiler/testData/ir/irText/firProblems/AllCandidates.fir.kt.txt

@@ -22,10 +22,11 @@ class MyCandidate {
 
 private fun <A : Any?> allCandidatesResult(allCandidates: Collection<MyCandidate>): @FlexibleNullability OverloadResolutionResultsImpl<@FlexibleNullability A?>? {
   return nameNotFound<@FlexibleNullability A?>().apply<@FlexibleNullability OverloadResolutionResultsImpl<@FlexibleNullability A?>?>(block = local fun @FlexibleNullability OverloadResolutionResultsImpl<@FlexibleNullability A?>?.<anonymous>() {
-    <this>.setAllCandidates(allCandidates = allCandidates.map<MyCandidate, ResolvedCall<A>>(transform = local fun <anonymous>(it: MyCandidate): ResolvedCall<A> {
+    $this$apply.setAllCandidates(allCandidates = allCandidates.map<MyCandidate, ResolvedCall<A>>(transform = local fun <anonymous>(it: MyCandidate): ResolvedCall<A> {
       return it.<get-resolvedCall>() as ResolvedCall<A>
     }
 ))
   }
 )
 }
+

compiler/testData/ir/irText/firProblems/typeVariableAfterBuildMap.fir.ir.txt

@@ -622,31 +622,31 @@ FILE fqName:<root> fileName:/typeVariableAfterBuildMap.kt
             <V>: kotlin.Int
             builderAction: FUN_EXPR type=kotlin.Function1<kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int>, kotlin.Unit> origin=LAMBDA
               FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int>) returnType:kotlin.Unit
-                $receiver: VALUE_PARAMETER name:<this> type:kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int>
+                $receiver: VALUE_PARAMETER name:$this$buildMap type:kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int>
                 BLOCK_BODY
                   TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                     CALL 'public abstract fun put (key: K of kotlin.collections.MutableMap, value: V of kotlin.collections.MutableMap): V of kotlin.collections.MutableMap? declared in kotlin.collections.MutableMap' type=kotlin.Int? origin=null
-                      $this: GET_VAR '<this>: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
+                      $this: GET_VAR '$this$buildMap: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
                       key: GET_OBJECT 'CLASS OBJECT name:PrivateToThis modality:FINAL visibility:public superTypes:[<root>.Visibility]' type=<root>.Visibilities.PrivateToThis
                       value: CONST Int type=kotlin.Int value=0
                   TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                     CALL 'public abstract fun put (key: K of kotlin.collections.MutableMap, value: V of kotlin.collections.MutableMap): V of kotlin.collections.MutableMap? declared in kotlin.collections.MutableMap' type=kotlin.Int? origin=null
-                      $this: GET_VAR '<this>: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
+                      $this: GET_VAR '$this$buildMap: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
                       key: GET_OBJECT 'CLASS OBJECT name:Private modality:FINAL visibility:public superTypes:[<root>.Visibility]' type=<root>.Visibilities.Private
                       value: CONST Int type=kotlin.Int value=0
                   TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                     CALL 'public abstract fun put (key: K of kotlin.collections.MutableMap, value: V of kotlin.collections.MutableMap): V of kotlin.collections.MutableMap? declared in kotlin.collections.MutableMap' type=kotlin.Int? origin=null
-                      $this: GET_VAR '<this>: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
+                      $this: GET_VAR '$this$buildMap: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
                       key: GET_OBJECT 'CLASS OBJECT name:Internal modality:FINAL visibility:public superTypes:[<root>.Visibility]' type=<root>.Visibilities.Internal
                       value: CONST Int type=kotlin.Int value=1
                   TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                     CALL 'public abstract fun put (key: K of kotlin.collections.MutableMap, value: V of kotlin.collections.MutableMap): V of kotlin.collections.MutableMap? declared in kotlin.collections.MutableMap' type=kotlin.Int? origin=null
-                      $this: GET_VAR '<this>: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
+                      $this: GET_VAR '$this$buildMap: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
                       key: GET_OBJECT 'CLASS OBJECT name:Protected modality:FINAL visibility:public superTypes:[<root>.Visibility]' type=<root>.Visibilities.Protected
                       value: CONST Int type=kotlin.Int value=1
                   TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                     CALL 'public abstract fun put (key: K of kotlin.collections.MutableMap, value: V of kotlin.collections.MutableMap): V of kotlin.collections.MutableMap? declared in kotlin.collections.MutableMap' type=kotlin.Int? origin=null
-                      $this: GET_VAR '<this>: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
+                      $this: GET_VAR '$this$buildMap: kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> declared in <root>.Visibilities.ORDERED_VISIBILITIES.<anonymous>' type=kotlin.collections.MutableMap<<root>.Visibility, kotlin.Int> origin=null
                       key: GET_OBJECT 'CLASS OBJECT name:Public modality:FINAL visibility:public superTypes:[<root>.Visibility]' type=<root>.Visibilities.Public
                       value: CONST Int type=kotlin.Int value=2
       FUN DEFAULT_PROPERTY_ACCESSOR name:<get-ORDERED_VISIBILITIES> visibility:private modality:FINAL <> ($this:<root>.Visibilities) returnType:kotlin.collections.Map<<root>.Visibility, kotlin.Int>

compiler/testData/ir/irText/firProblems/typeVariableAfterBuildMap.fir.kt.txt

@@ -163,13 +163,14 @@ object Visibilities {
 
   private val ORDERED_VISIBILITIES: Map<Visibility, Int>
     field = buildMap<Visibility, Int>(builderAction = local fun MutableMap<Visibility, Int>.<anonymous>() {
-      <this>.put(key = PrivateToThis, value = 0) /*~> Unit */
+      $this$buildMap.put(key = PrivateToThis, value = 0) /*~> Unit */
-      <this>.put(key = Private, value = 0) /*~> Unit */
+      $this$buildMap.put(key = Private, value = 0) /*~> Unit */
-      <this>.put(key = Internal, value = 1) /*~> Unit */
+      $this$buildMap.put(key = Internal, value = 1) /*~> Unit */
-      <this>.put(key = Protected, value = 1) /*~> Unit */
+      $this$buildMap.put(key = Protected, value = 1) /*~> Unit */
-      <this>.put(key = Public, value = 2) /*~> Unit */
+      $this$buildMap.put(key = Public, value = 2) /*~> Unit */
     }
 )
     private get
 
 }
+

compiler/testData/ir/irText/lambdas/destructuringInLambda.fir.ir.txt

@@ -140,7 +140,7 @@ FILE fqName:<root> fileName:/destructuringInLambda.kt
       EXPRESSION_BODY
         FUN_EXPR type=kotlin.Function1<<root>.A, kotlin.Int> origin=LAMBDA
           FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> (<destruct>:<root>.A) returnType:kotlin.Int
-            VALUE_PARAMETER name:<destruct> index:0 type:<root>.A
+            VALUE_PARAMETER DESTRUCTURED_OBJECT_PARAMETER name:<destruct> index:0 type:<root>.A
             BLOCK_BODY
               VAR name:y type:kotlin.Int [val]
                 CALL 'public final fun component2 (): kotlin.Int [operator] declared in <root>.A' type=kotlin.Int origin=COMPONENT_N(index=2)

compiler/testData/ir/irText/lambdas/extensionLambda.fir.ir.txt

@@ -8,8 +8,8 @@ FILE fqName:<root> fileName:/extensionLambda.kt
           $receiver: CONST String type=kotlin.String value="42"
           block: FUN_EXPR type=kotlin.Function1<kotlin.String, kotlin.Int> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:kotlin.String) returnType:kotlin.Int
-              $receiver: VALUE_PARAMETER name:<this> type:kotlin.String
+              $receiver: VALUE_PARAMETER name:$this$run type:kotlin.String
               BLOCK_BODY
                 RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.Int declared in <root>.test1'
                   CALL 'public open fun <get-length> (): kotlin.Int declared in kotlin.String' type=kotlin.Int origin=GET_PROPERTY
-                    $this: GET_VAR '<this>: kotlin.String declared in <root>.test1.<anonymous>' type=kotlin.String origin=null
+                    $this: GET_VAR '$this$run: kotlin.String declared in <root>.test1.<anonymous>' type=kotlin.String origin=null

compiler/testData/ir/irText/lambdas/extensionLambda.fir.kt.txt

@@ -1,6 +1,7 @@
 fun test1(): Int {
   return "42".run<String, Int>(block = local fun String.<anonymous>(): Int {
-    return <this>.<get-length>()
+    return $this$run.<get-length>()
   }
 )
 }
+

compiler/testData/ir/irText/lambdas/lambdaReturningUnit.fir.ir.txt

@@ -0,0 +1,15 @@
+FILE fqName:<root> fileName:/lambdaReturningUnit.kt
+  FUN name:flaf visibility:public modality:FINAL <> (block:kotlin.Function0<kotlin.Any?>) returnType:kotlin.Unit [inline]
+    VALUE_PARAMETER name:block index:0 type:kotlin.Function0<kotlin.Any?>
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        CALL 'public abstract fun invoke (): R of kotlin.Function0 [operator] declared in kotlin.Function0' type=kotlin.Any? origin=INVOKE
+          $this: GET_VAR 'block: kotlin.Function0<kotlin.Any?> declared in <root>.flaf' type=kotlin.Function0<kotlin.Any?> origin=VARIABLE_AS_FUNCTION
+  FUN name:box visibility:public modality:FINAL <> () returnType:kotlin.Unit [suspend]
+    BLOCK_BODY
+      CALL 'public final fun flaf (block: kotlin.Function0<kotlin.Any?>): kotlin.Unit [inline] declared in <root>' type=kotlin.Unit origin=null
+        block: FUN_EXPR type=kotlin.Function0<kotlin.Any?> origin=LAMBDA
+          FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> () returnType:kotlin.Any?
+            BLOCK_BODY
+              RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.Any? declared in <root>.box'
+                GET_OBJECT 'CLASS IR_EXTERNAL_DECLARATION_STUB OBJECT name:Unit modality:FINAL visibility:public superTypes:[kotlin.Any]' type=kotlin.Unit

compiler/testData/ir/irText/lambdas/lambdaReturningUnit.fir.kt.txt

@@ -0,0 +1,10 @@
+inline fun flaf(block: Function0<Any?>) {
+  block.invoke() /*~> Unit */
+}
+
+suspend fun box() {
+  flaf(block = local fun <anonymous>(): Any? {
+    return Unit
+  }
+)
+}

compiler/testData/ir/irText/lambdas/lambdaReturningUnit.ir.txt

@@ -0,0 +1,14 @@
+FILE fqName:<root> fileName:/lambdaReturningUnit.kt
+  FUN name:flaf visibility:public modality:FINAL <> (block:kotlin.Function0<kotlin.Any?>) returnType:kotlin.Unit [inline]
+    VALUE_PARAMETER name:block index:0 type:kotlin.Function0<kotlin.Any?>
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        CALL 'public abstract fun invoke (): R of kotlin.Function0 [operator] declared in kotlin.Function0' type=kotlin.Any? origin=INVOKE
+          $this: GET_VAR 'block: kotlin.Function0<kotlin.Any?> declared in <root>.flaf' type=kotlin.Function0<kotlin.Any?> origin=VARIABLE_AS_FUNCTION
+  FUN name:box visibility:public modality:FINAL <> () returnType:kotlin.Unit [suspend]
+    BLOCK_BODY
+      CALL 'public final fun flaf (block: kotlin.Function0<kotlin.Any?>): kotlin.Unit [inline] declared in <root>' type=kotlin.Unit origin=null
+        block: FUN_EXPR type=kotlin.Function0<kotlin.Unit> origin=LAMBDA
+          FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> () returnType:kotlin.Unit
+            BLOCK_BODY
+              GET_OBJECT 'CLASS IR_EXTERNAL_DECLARATION_STUB OBJECT name:Unit modality:FINAL visibility:public superTypes:[kotlin.Any]' type=kotlin.Unit

compiler/testData/ir/irText/lambdas/lambdaReturningUnit.kt

@@ -0,0 +1,12 @@
+// With FIR the type of the lambda in box is () -> Any?
+// With old frontend the type of the lambda is () -> Unit
+
+inline fun flaf(block: () -> Any?) {
+    block()
+}
+
+suspend fun box() {
+    flaf {
+        Unit
+    }
+}

compiler/testData/ir/irText/lambdas/lambdaReturningUnit.kt.txt

@@ -0,0 +1,11 @@
+inline fun flaf(block: Function0<Any?>) {
+  block.invoke() /*~> Unit */
+}
+
+suspend fun box() {
+  flaf(block = local fun <anonymous>() {
+    Unit
+  }
+)
+}
+

compiler/testData/ir/irText/lambdas/multipleImplicitReceivers.fir.ir.txt

@@ -92,7 +92,7 @@ FILE fqName:<root> fileName:/multipleImplicitReceivers.kt
           receiver: GET_OBJECT 'CLASS OBJECT name:A modality:FINAL visibility:public superTypes:[kotlin.Any]' type=<root>.A
           block: FUN_EXPR type=kotlin.Function1<<root>.A, kotlin.Int> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.A) returnType:kotlin.Int
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.A
+              $receiver: VALUE_PARAMETER name:$this$with type:<root>.A
               BLOCK_BODY
                 RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.Int declared in <root>.test'
                   CALL 'public final fun with <T, R> (receiver: T of kotlin.StandardKt.with, block: @[ExtensionFunctionType] kotlin.Function1<T of kotlin.StandardKt.with, R of kotlin.StandardKt.with>): R of kotlin.StandardKt.with [inline] declared in kotlin.StandardKt' type=kotlin.Int origin=null
@@ -101,7 +101,7 @@ FILE fqName:<root> fileName:/multipleImplicitReceivers.kt
                     receiver: GET_VAR 'fooImpl: <root>.IFoo declared in <root>.test' type=<root>.IFoo origin=null
                     block: FUN_EXPR type=kotlin.Function1<<root>.IFoo, kotlin.Int> origin=LAMBDA
                       FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.IFoo) returnType:kotlin.Int
-                        $receiver: VALUE_PARAMETER name:<this> type:<root>.IFoo
+                        $receiver: VALUE_PARAMETER name:$this$with type:<root>.IFoo
                         BLOCK_BODY
                           RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.Int declared in <root>.test.<anonymous>'
                             CALL 'public final fun with <T, R> (receiver: T of kotlin.StandardKt.with, block: @[ExtensionFunctionType] kotlin.Function1<T of kotlin.StandardKt.with, R of kotlin.StandardKt.with>): R of kotlin.StandardKt.with [inline] declared in kotlin.StandardKt' type=kotlin.Int origin=null
@@ -110,11 +110,11 @@ FILE fqName:<root> fileName:/multipleImplicitReceivers.kt
                               receiver: GET_VAR 'invokeImpl: <root>.IInvoke declared in <root>.test' type=<root>.IInvoke origin=null
                               block: FUN_EXPR type=kotlin.Function1<<root>.IInvoke, kotlin.Int> origin=LAMBDA
                                 FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.IInvoke) returnType:kotlin.Int
-                                  $receiver: VALUE_PARAMETER name:<this> type:<root>.IInvoke
+                                  $receiver: VALUE_PARAMETER name:$this$with type:<root>.IInvoke
                                   BLOCK_BODY
                                     RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.Int declared in <root>.test.<anonymous>.<anonymous>'
                                       CALL 'public open fun invoke (): kotlin.Int [operator] declared in <root>.IInvoke' type=kotlin.Int origin=null
-                                        $this: GET_VAR '<this>: <root>.IInvoke declared in <root>.test.<anonymous>.<anonymous>.<anonymous>' type=<root>.IInvoke origin=null
+                                        $this: GET_VAR '$this$with: <root>.IInvoke declared in <root>.test.<anonymous>.<anonymous>.<anonymous>' type=<root>.IInvoke origin=null
                                         $receiver: CALL 'public open fun <get-foo> (): <root>.B declared in <root>.IFoo' type=<root>.B origin=GET_PROPERTY
-                                          $this: GET_VAR '<this>: <root>.IFoo declared in <root>.test.<anonymous>.<anonymous>' type=<root>.IFoo origin=null
+                                          $this: GET_VAR '$this$with: <root>.IFoo declared in <root>.test.<anonymous>.<anonymous>' type=<root>.IFoo origin=null
-                                          $receiver: GET_VAR '<this>: <root>.A declared in <root>.test.<anonymous>' type=<root>.A origin=null
+                                          $receiver: GET_VAR '$this$with: <root>.A declared in <root>.test.<anonymous>' type=<root>.A origin=null

compiler/testData/ir/irText/lambdas/multipleImplicitReceivers.fir.kt.txt

@@ -35,7 +35,7 @@ fun test(fooImpl: IFoo, invokeImpl: IInvoke) {
   with<A, Int>(receiver = A, block = local fun A.<anonymous>(): Int {
     return with<IFoo, Int>(receiver = fooImpl, block = local fun IFoo.<anonymous>(): Int {
       return with<IInvoke, Int>(receiver = invokeImpl, block = local fun IInvoke.<anonymous>(): Int {
-        return (<this>, (<this>, <this>).<get-foo>()).invoke()
+        return ($this$with, ($this$with, $this$with).<get-foo>()).invoke()
       }
 )
     }
@@ -43,3 +43,4 @@ fun test(fooImpl: IFoo, invokeImpl: IInvoke) {
   }
 ) /*~> Unit */
 }
+

compiler/testData/ir/irText/stubs/builtinMap.fir.ir.txt

@@ -24,11 +24,11 @@ FILE fqName:<root> fileName:/builtinMap.kt
                 p0: GET_VAR '<this>: kotlin.collections.Map<out K1 of <root>.plus, V1 of <root>.plus> declared in <root>.plus' type=kotlin.collections.Map<out K1 of <root>.plus, V1 of <root>.plus> origin=null
               block: FUN_EXPR type=kotlin.Function1<java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?>, kotlin.Unit> origin=LAMBDA
                 FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?>) returnType:kotlin.Unit
-                  $receiver: VALUE_PARAMETER name:<this> type:java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?>
+                  $receiver: VALUE_PARAMETER name:$this$apply type:java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?>
                   BLOCK_BODY
                     TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
                       CALL 'public open fun put (p0: @[FlexibleNullability] K of java.util.LinkedHashMap?, p1: @[FlexibleNullability] V of java.util.LinkedHashMap?): V of java.util.LinkedHashMap? [fake_override] declared in java.util.LinkedHashMap' type=V1 of <root>.plus? origin=null
-                        $this: GET_VAR '<this>: java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> declared in <root>.plus.<anonymous>' type=java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> origin=null
+                        $this: GET_VAR '$this$apply: java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> declared in <root>.plus.<anonymous>' type=java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> origin=null
                         p0: CALL 'public final fun <get-first> (): A of kotlin.Pair declared in kotlin.Pair' type=K1 of <root>.plus origin=GET_PROPERTY
                           $this: GET_VAR 'pair: kotlin.Pair<K1 of <root>.plus, V1 of <root>.plus> declared in <root>.plus' type=kotlin.Pair<K1 of <root>.plus, V1 of <root>.plus> origin=null
                         p1: CALL 'public final fun <get-second> (): B of kotlin.Pair declared in kotlin.Pair' type=V1 of <root>.plus origin=GET_PROPERTY

compiler/testData/ir/irText/stubs/builtinMap.fir.kt.txt

@@ -2,8 +2,9 @@ fun <K1 : Any?, V1 : Any?> Map<out K1, V1>.plus(pair: Pair<K1, V1>): Map<K1, V1>
   return when {
     <this>.isEmpty() -> mapOf<K1, V1>(pair = pair)
     else -> LinkedHashMap<@FlexibleNullability K1?, @FlexibleNullability V1?>(p0 = <this>).apply<LinkedHashMap<@FlexibleNullability K1?, @FlexibleNullability V1?>>(block = local fun LinkedHashMap<@FlexibleNullability K1?, @FlexibleNullability V1?>.<anonymous>() {
-      <this>.put(p0 = pair.<get-first>(), p1 = pair.<get-second>()) /*~> Unit */
+      $this$apply.put(p0 = pair.<get-first>(), p1 = pair.<get-second>()) /*~> Unit */
     }
 )
   }
 }
+

compiler/testData/ir/irText/types/castsInsideCoroutineInference.fir.ir.txt

@@ -12,19 +12,19 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
           <T>: R of <root>.scopedFlow
           block: FUN_EXPR type=kotlin.coroutines.SuspendFunction1<<root>.FlowCollector<R of <root>.scopedFlow>, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.FlowCollector<R of <root>.scopedFlow>) returnType:kotlin.Unit [suspend]
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.FlowCollector<R of <root>.scopedFlow>
+              $receiver: VALUE_PARAMETER name:$this$flow type:<root>.FlowCollector<R of <root>.scopedFlow>
               BLOCK_BODY
                 VAR name:collector type:<root>.FlowCollector<R of <root>.scopedFlow> [val]
-                  GET_VAR '<this>: <root>.FlowCollector<R of <root>.scopedFlow> declared in <root>.scopedFlow.<anonymous>' type=<root>.FlowCollector<R of <root>.scopedFlow> origin=null
+                  GET_VAR '$this$flow: <root>.FlowCollector<R of <root>.scopedFlow> declared in <root>.scopedFlow.<anonymous>' type=<root>.FlowCollector<R of <root>.scopedFlow> origin=null
                 CALL 'public final fun flowScope <R> (block: @[ExtensionFunctionType] kotlin.coroutines.SuspendFunction1<<root>.CoroutineScope, R of <root>.flowScope>): R of <root>.flowScope [suspend] declared in <root>' type=kotlin.Unit origin=null
                   <R>: kotlin.Unit
                   block: FUN_EXPR type=kotlin.coroutines.SuspendFunction1<<root>.CoroutineScope, kotlin.Unit> origin=LAMBDA
                     FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.CoroutineScope) returnType:kotlin.Unit [suspend]
-                      $receiver: VALUE_PARAMETER name:<this> type:<root>.CoroutineScope
+                      $receiver: VALUE_PARAMETER name:$this$flowScope type:<root>.CoroutineScope
                       BLOCK_BODY
                         CALL 'public abstract fun invoke (p1: P1 of kotlin.coroutines.SuspendFunction2, p2: P2 of kotlin.coroutines.SuspendFunction2): R of kotlin.coroutines.SuspendFunction2 [suspend,operator] declared in kotlin.coroutines.SuspendFunction2' type=kotlin.Unit origin=null
                           $this: GET_VAR 'block: @[ExtensionFunctionType] kotlin.coroutines.SuspendFunction2<<root>.CoroutineScope, <root>.FlowCollector<R of <root>.scopedFlow>, kotlin.Unit> declared in <root>.scopedFlow' type=@[ExtensionFunctionType] kotlin.coroutines.SuspendFunction2<<root>.CoroutineScope, <root>.FlowCollector<R of <root>.scopedFlow>, kotlin.Unit> origin=VARIABLE_AS_FUNCTION
-                          p1: GET_VAR '<this>: <root>.CoroutineScope declared in <root>.scopedFlow.<anonymous>.<anonymous>' type=<root>.CoroutineScope origin=null
+                          p1: GET_VAR '$this$flowScope: <root>.CoroutineScope declared in <root>.scopedFlow.<anonymous>.<anonymous>' type=<root>.CoroutineScope origin=null
                           p2: GET_VAR 'val collector: <root>.FlowCollector<R of <root>.scopedFlow> [val] declared in <root>.scopedFlow.<anonymous>' type=<root>.FlowCollector<R of <root>.scopedFlow> origin=null
   FUN name:onCompletion visibility:public modality:FINAL <T> ($receiver:<root>.Flow<T of <root>.onCompletion>, action:@[ExtensionFunctionType] kotlin.coroutines.SuspendFunction2<<root>.FlowCollector<T of <root>.onCompletion>, @[ParameterName(name = 'cause')] kotlin.Throwable?, kotlin.Unit>) returnType:<root>.Flow<T of <root>.onCompletion>
     TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?]
@@ -36,12 +36,12 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
           <T>: T of <root>.onCompletion
           block: FUN_EXPR type=kotlin.coroutines.SuspendFunction1<<root>.FlowCollector<T of <root>.onCompletion>, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.FlowCollector<T of <root>.onCompletion>) returnType:kotlin.Unit [suspend]
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.FlowCollector<T of <root>.onCompletion>
+              $receiver: VALUE_PARAMETER name:$this$unsafeFlow type:<root>.FlowCollector<T of <root>.onCompletion>
               BLOCK_BODY
                 VAR name:safeCollector type:<root>.SafeCollector<T of <root>.onCompletion> [val]
                   CONSTRUCTOR_CALL 'public constructor <init> (collector: <root>.FlowCollector<T of <root>.SafeCollector>) [primary] declared in <root>.SafeCollector' type=<root>.SafeCollector<T of <root>.onCompletion> origin=null
                     <class: T>: T of <root>.onCompletion
-                    collector: GET_VAR '<this>: <root>.FlowCollector<T of <root>.onCompletion> declared in <root>.onCompletion.<anonymous>' type=<root>.FlowCollector<T of <root>.onCompletion> origin=null
+                    collector: GET_VAR '$this$unsafeFlow: <root>.FlowCollector<T of <root>.onCompletion> declared in <root>.onCompletion.<anonymous>' type=<root>.FlowCollector<T of <root>.onCompletion> origin=null
                 CALL 'public final fun invokeSafely <T> (action: @[ExtensionFunctionType] kotlin.coroutines.SuspendFunction2<<root>.FlowCollector<T of <root>.invokeSafely>, @[ParameterName(name = 'cause')] kotlin.Throwable?, kotlin.Unit>): kotlin.Unit [suspend] declared in <root>' type=kotlin.Unit origin=null
                   <T>: T of <root>.onCompletion
                   $receiver: GET_VAR 'val safeCollector: <root>.SafeCollector<T of <root>.onCompletion> [val] declared in <root>.onCompletion.<anonymous>' type=<root>.SafeCollector<T of <root>.onCompletion> origin=null
@@ -74,7 +74,7 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
           $receiver: GET_VAR '<this>: <root>.Flow<T of <root>.onCompletion> declared in <root>.onCompletion' type=<root>.Flow<T of <root>.onCompletion> origin=null
           action: FUN_EXPR type=kotlin.coroutines.SuspendFunction2<<root>.FlowCollector<T of <root>.onCompletion>, @[ParameterName(name = 'cause')] kotlin.Throwable?, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.FlowCollector<T of <root>.onCompletion>, it:@[ParameterName(name = 'cause')] kotlin.Throwable?) returnType:kotlin.Unit [suspend]
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.FlowCollector<T of <root>.onCompletion>
+              $receiver: VALUE_PARAMETER name:$this$onCompletion type:<root>.FlowCollector<T of <root>.onCompletion>
               VALUE_PARAMETER name:it index:0 type:@[ParameterName(name = 'cause')] kotlin.Throwable?
               BLOCK_BODY
                 CALL 'public abstract fun invoke (p1: P1 of kotlin.coroutines.SuspendFunction1): R of kotlin.coroutines.SuspendFunction1 [suspend,operator] declared in kotlin.coroutines.SuspendFunction1' type=kotlin.Unit origin=null
@@ -90,12 +90,12 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
           $receiver: GET_VAR '<this>: <root>.CoroutineScope declared in <root>.asFairChannel' type=<root>.CoroutineScope origin=null
           block: FUN_EXPR type=kotlin.coroutines.SuspendFunction1<<root>.ProducerScope<kotlin.Any>, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.ProducerScope<kotlin.Any>) returnType:kotlin.Unit [suspend]
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.ProducerScope<kotlin.Any>
+              $receiver: VALUE_PARAMETER name:$this$produce type:<root>.ProducerScope<kotlin.Any>
               BLOCK_BODY
                 VAR name:channel type:<root>.ChannelCoroutine<kotlin.Any> [val]
                   TYPE_OP type=<root>.ChannelCoroutine<kotlin.Any> origin=CAST typeOperand=<root>.ChannelCoroutine<kotlin.Any>
                     CALL 'public abstract fun <get-channel> (): <root>.SendChannel<E of <root>.ProducerScope> declared in <root>.ProducerScope' type=<root>.SendChannel<kotlin.Nothing> origin=GET_PROPERTY
-                      $this: GET_VAR '<this>: <root>.ProducerScope<kotlin.Any> declared in <root>.asFairChannel.<anonymous>' type=<root>.ProducerScope<kotlin.Nothing> origin=null
+                      $this: GET_VAR '$this$produce: <root>.ProducerScope<kotlin.Any> declared in <root>.asFairChannel.<anonymous>' type=<root>.ProducerScope<kotlin.Nothing> origin=null
                 CALL 'public final fun collect <T> (action: kotlin.coroutines.SuspendFunction1<@[ParameterName(name = 'value')] T of <root>.collect, kotlin.Unit>): kotlin.Unit [inline,suspend] declared in <root>' type=kotlin.Unit origin=null
                   <T>: kotlin.Any?
                   $receiver: GET_VAR 'flow: <root>.Flow<*> declared in <root>.asFairChannel' type=<root>.Flow<*> origin=null
@@ -128,7 +128,7 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
           $receiver: GET_VAR '<this>: <root>.CoroutineScope declared in <root>.asChannel' type=<root>.CoroutineScope origin=null
           block: FUN_EXPR type=kotlin.coroutines.SuspendFunction1<<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any>, kotlin.Unit> origin=LAMBDA
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any>) returnType:kotlin.Unit [suspend]
-              $receiver: VALUE_PARAMETER name:<this> type:<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any>
+              $receiver: VALUE_PARAMETER name:$this$produce type:<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any>
               BLOCK_BODY
                 CALL 'public final fun collect <T> (action: kotlin.coroutines.SuspendFunction1<@[ParameterName(name = 'value')] T of <root>.collect, kotlin.Unit>): kotlin.Unit [inline,suspend] declared in <root>' type=kotlin.Unit origin=null
                   <T>: kotlin.Any?
@@ -140,7 +140,7 @@ FILE fqName:<root> fileName:/castsInsideCoroutineInference.kt
                         RETURN type=kotlin.Nothing from='local final fun <anonymous> (value: @[ParameterName(name = 'value')] kotlin.Any?): kotlin.Unit [suspend] declared in <root>.asChannel.<anonymous>'
                           CALL 'public abstract fun send (e: E of <root>.SendChannel): kotlin.Unit [suspend] declared in <root>.SendChannel' type=kotlin.Unit origin=null
                             $this: CALL 'public abstract fun <get-channel> (): <root>.SendChannel<E of <root>.ProducerScope> declared in <root>.ProducerScope' type=<root>.SendChannel<@[ParameterName(name = 'value')] kotlin.Any> origin=GET_PROPERTY
-                              $this: GET_VAR '<this>: <root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any> declared in <root>.asChannel.<anonymous>' type=<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any> origin=null
+                              $this: GET_VAR '$this$produce: <root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any> declared in <root>.asChannel.<anonymous>' type=<root>.ProducerScope<@[ParameterName(name = 'value')] kotlin.Any> origin=null
                             e: BLOCK type=@[ParameterName(name = 'value')] kotlin.Any origin=ELVIS
                               VAR IR_TEMPORARY_VARIABLE name:tmp_1 type:@[ParameterName(name = 'value')] kotlin.Any? [val]
                                 GET_VAR 'value: @[ParameterName(name = 'value')] kotlin.Any? declared in <root>.asChannel.<anonymous>.<anonymous>' type=@[ParameterName(name = 'value')] kotlin.Any? origin=null

compiler/testData/ir/irText/types/castsInsideCoroutineInference.fir.kt.txt

@@ -1,9 +1,9 @@
 @OptIn(markerClass = [ExperimentalTypeInference::class])
 fun <R : Any?> scopedFlow(@BuilderInference block: @ExtensionFunctionType SuspendFunction2<CoroutineScope, FlowCollector<R>, Unit>): Flow<R> {
   return flow<R>(block = local suspend fun FlowCollector<R>.<anonymous>() {
-    val collector: FlowCollector<R> = <this>
+    val collector: FlowCollector<R> = $this$flow
     flowScope<Unit>(block = local suspend fun CoroutineScope.<anonymous>() {
-      block.invoke(p1 = <this>, p2 = collector)
+      block.invoke(p1 = $this$flowScope, p2 = collector)
     }
 )
   }
@@ -12,7 +12,7 @@ fun <R : Any?> scopedFlow(@BuilderInference block: @ExtensionFunctionType Suspen
 
 fun <T : Any?> Flow<T>.onCompletion(action: @ExtensionFunctionType SuspendFunction2<FlowCollector<T>, @ParameterName(name = "cause") Throwable?, Unit>): Flow<T> {
   return unsafeFlow<T>(block = local suspend fun FlowCollector<T>.<anonymous>() {
-    val safeCollector: SafeCollector<T> = SafeCollector<T>(collector = <this>)
+    val safeCollector: SafeCollector<T> = SafeCollector<T>(collector = $this$unsafeFlow)
     safeCollector.invokeSafely<T>(action = action)
   }
 )
@@ -36,7 +36,7 @@ fun <T : Any?> Flow<T>.onCompletion(action: SuspendFunction1<@ParameterName(name
 
 private fun CoroutineScope.asFairChannel(flow: Flow<*>): ReceiveChannel<Any> {
   return <this>.produce<Any>(block = local suspend fun ProducerScope<Any>.<anonymous>() {
-    val channel: ChannelCoroutine<Any> = <this>.<get-channel>() as ChannelCoroutine<Any>
+    val channel: ChannelCoroutine<Any> = $this$produce.<get-channel>() as ChannelCoroutine<Any>
     flow.collect<Any?>(action = local suspend fun <anonymous>(value: @ParameterName(name = "value") Any?) {
       return channel.sendFair(element = { // BLOCK
         val <elvis>: @ParameterName(name = "value") Any? = value
@@ -54,7 +54,7 @@ private fun CoroutineScope.asFairChannel(flow: Flow<*>): ReceiveChannel<Any> {
 private fun CoroutineScope.asChannel(flow: Flow<*>): ReceiveChannel<Any> {
   return <this>.produce<@ParameterName(name = "value") Any>(block = local suspend fun ProducerScope<@ParameterName(name = "value") Any>.<anonymous>() {
     flow.collect<Any?>(action = local suspend fun <anonymous>(value: @ParameterName(name = "value") Any?) {
-      return <this>.<get-channel>().send(e = { // BLOCK
+      return $this$produce.<get-channel>().send(e = { // BLOCK
         val <elvis>: @ParameterName(name = "value") Any? = value
         when {
           EQEQ(arg0 = <elvis>, arg1 = null) -> Any()
@@ -141,3 +141,4 @@ interface SendChannel<in E : Any?> {
   abstract suspend fun send(e: E)
 
 }
+

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

@@ -2462,6 +2462,12 @@ public class IrTextTestGenerated extends AbstractIrTextTest {
             runTest("compiler/testData/ir/irText/lambdas/justLambda.kt");
         }
 
+        @Test
+        @TestMetadata("lambdaReturningUnit.kt")
+        public void testLambdaReturningUnit() throws Exception {
+            runTest("compiler/testData/ir/irText/lambdas/lambdaReturningUnit.kt");
+        }
+
         @Test
         @TestMetadata("localFunction.kt")
         public void testLocalFunction() throws Exception {

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/backend/handlers/DebugRunner.kt

@@ -11,6 +11,8 @@ import com.sun.jdi.request.EventRequest.SUSPEND_ALL
 import com.sun.jdi.request.StepRequest
 import com.sun.tools.jdi.SocketAttachingConnector
 import org.jetbrains.kotlin.test.TargetBackend
+import org.jetbrains.kotlin.test.model.FrontendKind
+import org.jetbrains.kotlin.test.model.FrontendKinds
 import org.jetbrains.kotlin.test.model.TestModule
 import org.jetbrains.kotlin.test.services.JUnit5Assertions.assertEqualsToFile
 import org.jetbrains.kotlin.test.services.TestServices
@@ -27,12 +29,15 @@ abstract class DebugRunner(testServices: TestServices) : JvmBoxRunner(testServic
         const val FORCE_STEP_INTO_MARKER = "// FORCE_STEP_INTO"
         const val JVM_EXPECTATIONS_MARKER = "$EXPECTATIONS_MARKER JVM"
         const val JVM_IR_EXPECTATIONS_MARKER = "$EXPECTATIONS_MARKER JVM_IR"
+        const val CLASSIC_FRONTEND_EXPECTATIONS_MARKER = "$EXPECTATIONS_MARKER CLASSIC_FRONTEND"
+        const val FIR_EXPECTATIONS_MARKER = "$EXPECTATIONS_MARKER FIR"
 
         val BOX_MAIN_FILE_CLASS_NAME = BOX_MAIN_FILE_NAME.replace(".kt", "Kt")
     }
 
     private var wholeFile = File("")
     private var backend = TargetBackend.JVM
+    private var frontend: FrontendKind<*> = FrontendKinds.ClassicFrontend
 
     abstract fun storeStep(loggedItems: ArrayList<LoggedData>, event: Event)
 
@@ -42,8 +47,9 @@ abstract class DebugRunner(testServices: TestServices) : JvmBoxRunner(testServic
         classPath: List<URL>,
         mainClassAndArguments: List<String>
     ): Process {
-        // Extract target backend and the full test file used to extract test expectations.
+        // Extract target backend, frontend, and the full test file used to extract test expectations.
         backend = module.targetBackend ?: backend
+        frontend = module.frontendKind
         wholeFile = module.files.single { it.name == "test.kt" }.originalFile
 
         // Setup the java process to suspend waiting for debugging connection on a free port.
@@ -187,6 +193,7 @@ abstract class DebugRunner(testServices: TestServices) : JvmBoxRunner(testServic
         }
 
         var currentBackend = TargetBackend.ANY
+        var currentFrontend = frontend
         for (line in lineIterator) {
             if (line.isEmpty()) {
                 actual.add(line)
@@ -198,11 +205,22 @@ abstract class DebugRunner(testServices: TestServices) : JvmBoxRunner(testServic
                     EXPECTATIONS_MARKER -> TargetBackend.ANY
                     JVM_EXPECTATIONS_MARKER -> TargetBackend.JVM
                     JVM_IR_EXPECTATIONS_MARKER -> TargetBackend.JVM_IR
+                    CLASSIC_FRONTEND_EXPECTATIONS_MARKER -> currentBackend
+                    FIR_EXPECTATIONS_MARKER -> currentBackend
+                    else -> error("Expected JVM backend: $line")
+                }
+                currentFrontend = when (line) {
+                    EXPECTATIONS_MARKER -> frontend
+                    JVM_EXPECTATIONS_MARKER -> currentFrontend
+                    JVM_IR_EXPECTATIONS_MARKER -> currentFrontend
+                    CLASSIC_FRONTEND_EXPECTATIONS_MARKER -> FrontendKinds.ClassicFrontend
+                    FIR_EXPECTATIONS_MARKER -> FrontendKinds.FIR
                     else -> error("Expected JVM backend: $line")
                 }
                 continue
             }
-            if (currentBackend == TargetBackend.ANY || currentBackend == backend) {
+            if ((currentBackend == TargetBackend.ANY || currentBackend == backend) &&
+                currentFrontend == frontend) {
                 if (actualLineNumbersIterator.hasNext()) {
                     actual.add(actualLineNumbersIterator.next())
                 }

compiler/tests-gen/org/jetbrains/kotlin/ir/KlibTextTestCaseGenerated.java

@@ -1831,6 +1831,11 @@ public class KlibTextTestCaseGenerated extends AbstractKlibTextTestCase {
             runTest("compiler/testData/ir/irText/lambdas/justLambda.kt");
         }
 
+        @TestMetadata("lambdaReturningUnit.kt")
+        public void testLambdaReturningUnit() throws Exception {
+            runTest("compiler/testData/ir/irText/lambdas/lambdaReturningUnit.kt");
+        }
+
         @TestMetadata("localFunction.kt")
         public void testLocalFunction() throws Exception {
             runTest("compiler/testData/ir/irText/lambdas/localFunction.kt");