FIR2IR: introduce implicit casts for extension receivers

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/CallAndReferenceGenerator.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.fir.backend.generators
 
-import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.fir.FirFakeSourceElementKind
 import org.jetbrains.kotlin.fir.backend.*
 import org.jetbrains.kotlin.fir.declarations.*
@@ -720,7 +719,18 @@ class CallAndReferenceGenerator(
                     dispatchReceiver = qualifiedAccess.findIrDispatchReceiver(explicitReceiverExpression)
                 }
                 if (ownerFunction?.extensionReceiverParameter != null) {
-                    extensionReceiver = qualifiedAccess.findIrExtensionReceiver(explicitReceiverExpression)
+                    extensionReceiver = qualifiedAccess.findIrExtensionReceiver(explicitReceiverExpression)?.let {
+                        ((qualifiedAccess.calleeReference as FirResolvedNamedReference)
+                            .resolvedSymbol.fir as? FirCallableMemberDeclaration)?.receiverTypeRef?.let { receiverType ->
+                            with(visitor.implicitCastInserter) {
+                                it.cast(
+                                    qualifiedAccess.extensionReceiver,
+                                    qualifiedAccess.extensionReceiver.typeRef,
+                                    receiverType
+                                )
+                            }
+                        } ?: it
+                    }
                 }
                 this
             }

compiler/testData/codegen/box/javaInterop/notNullAssertions/nullabilityAssertionOnInlineFunExtensionReceiver.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: test.kt

compiler/testData/codegen/box/javaInterop/notNullAssertions/nullabilityAssertionOnPrivateMemberExtensionReceiver.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: test.kt

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

@@ -9,5 +9,5 @@ private operator fun J.component2(): Int {
 fun test() {
   val <destruct>: J? = j()
   val a: Int = <destruct>.component1()
-  val b: Int = <destruct>.component2()
+  val b: Int = <destruct> /*!! J */.component2()
 }

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

@@ -18,4 +18,5 @@ FILE fqName:<root> fileName:/implicitNotNullInDestructuringAssignment.kt
           $receiver: GET_VAR 'val tmp_0: <root>.J? [val] declared in <root>.test' type=<root>.J? origin=null
       VAR name:b type:kotlin.Int [val]
         CALL 'private final fun component2 (): kotlin.Int [operator] declared in <root>' type=kotlin.Int origin=null
-          $receiver: GET_VAR 'val tmp_0: <root>.J? [val] declared in <root>.test' type=<root>.J? origin=null
+          $receiver: TYPE_OP type=<root>.J origin=IMPLICIT_NOTNULL typeOperand=<root>.J
+            GET_VAR 'val tmp_0: <root>.J? [val] declared in <root>.test' type=<root>.J? origin=null

compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.kt.txt

@@ -80,7 +80,7 @@ fun test3() {
 }
 
 fun test4() {
-  val <destruct>: IndexedValue<P?> = listOfNotNull().withIndex<P?>().first<IndexedValue<P?>>()
+  val <destruct>: IndexedValue<P?> = listOfNotNull() /*!! List<P?> */.withIndex<P?>().first<IndexedValue<P?>>()
   val x: Int = <destruct>.component1()
   val y: P? = <destruct>.component2()
   use(x = x, y = y /*!! P */)

compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.txt

@@ -179,7 +179,8 @@ FILE fqName:<root> fileName:/enhancedNullabilityInDestructuringAssignment.kt
           <T>: kotlin.collections.IndexedValue<<root>.P?>
           $receiver: CALL 'public final fun withIndex <T> (): kotlin.collections.Iterable<kotlin.collections.IndexedValue<T of kotlin.collections.withIndex>> declared in kotlin.collections' type=kotlin.collections.Iterable<kotlin.collections.IndexedValue<<root>.P?>> origin=null
             <T>: <root>.P?
-            $receiver: CALL 'public open fun listOfNotNull (): kotlin.collections.List<<root>.P?>? declared in <root>.J' type=kotlin.collections.List<<root>.P?>? origin=null
+            $receiver: TYPE_OP type=kotlin.collections.List<<root>.P?> origin=IMPLICIT_NOTNULL typeOperand=kotlin.collections.List<<root>.P?>
+              CALL 'public open fun listOfNotNull (): kotlin.collections.List<<root>.P?>? declared in <root>.J' type=kotlin.collections.List<<root>.P?>? origin=null
       VAR name:x type:kotlin.Int [val]
         CALL 'public final fun component1 (): kotlin.Int [operator] declared in kotlin.collections.IndexedValue' type=kotlin.Int origin=null
           $this: GET_VAR 'val tmp_3: kotlin.collections.IndexedValue<<root>.P?> [val] declared in <root>.test4' type=kotlin.collections.IndexedValue<<root>.P?> origin=null

compiler/testData/ir/irText/types/nullChecks/nullabilityAssertionOnExtensionReceiver.fir.kt.txt

@@ -14,9 +14,9 @@ class C {
 }
 
 fun testExt() {
-  s().extension()
+  s() /*!! String */.extension()
 }
 
 fun C.testMemberExt() {
-  (<this>, s()).memberExtension()
+  (<this>, s() /*!! String */).memberExtension()
 }

compiler/testData/ir/irText/types/nullChecks/nullabilityAssertionOnExtensionReceiver.fir.txt

@@ -28,10 +28,12 @@ FILE fqName:<root> fileName:/nullabilityAssertionOnExtensionReceiver.kt
   FUN name:testExt visibility:public modality:FINAL <> () returnType:kotlin.Unit
     BLOCK_BODY
       CALL 'public final fun extension (): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
-        $receiver: CALL 'public open fun s (): kotlin.String? declared in <root>.J' type=kotlin.String? origin=null
+        $receiver: TYPE_OP type=kotlin.String origin=IMPLICIT_NOTNULL typeOperand=kotlin.String
+          CALL 'public open fun s (): kotlin.String? declared in <root>.J' type=kotlin.String? origin=null
   FUN name:testMemberExt visibility:public modality:FINAL <> ($receiver:<root>.C) returnType:kotlin.Unit
     $receiver: VALUE_PARAMETER name:<this> type:<root>.C
     BLOCK_BODY
       CALL 'public final fun memberExtension (): kotlin.Unit declared in <root>.C' type=kotlin.Unit origin=null
         $this: GET_VAR '<this>: <root>.C declared in <root>.testMemberExt' type=<root>.C origin=null
-        $receiver: CALL 'public open fun s (): kotlin.String? declared in <root>.J' type=kotlin.String? origin=null
+        $receiver: TYPE_OP type=kotlin.String origin=IMPLICIT_NOTNULL typeOperand=kotlin.String
+          CALL 'public open fun s (): kotlin.String? declared in <root>.J' type=kotlin.String? origin=null