FIR: Make LHS of FirVariableAssignment a FirExpression

This way references can even be resolved for erroneous assignments
(e.g. function call, if expression, ... on LHS)

^KT-54648 Fixed

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/BuilderConfigurator.kt

@@ -45,8 +45,8 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
             withCopy()
         }
 
-        val qualifiedAccessBuilder by builder {
-            fields from qualifiedAccess without "calleeReference"
+        val qualifiedAccessExpressionBuilder by builder {
+            fields from qualifiedAccessExpression without "calleeReference"
         }
 
         val callBuilder by builder {
@@ -79,7 +79,7 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
         }
 
         val abstractFunctionCallBuilder by builder {
-            parents += qualifiedAccessBuilder
+            parents += qualifiedAccessExpressionBuilder
             parents += callBuilder
             fields from functionCall
         }
@@ -152,12 +152,12 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
         }
 
         builder(propertyAccessExpression) {
-            parents += qualifiedAccessBuilder
+            parents += qualifiedAccessExpressionBuilder
             defaultNoReceivers()
         }
 
         builder(callableReferenceAccess) {
-            parents += qualifiedAccessBuilder
+            parents += qualifiedAccessExpressionBuilder
             defaultNull("explicitReceiver")
             defaultNoReceivers()
             defaultFalse("hasQuestionMarkAtLHS")
@@ -245,7 +245,7 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
         }
 
         builder(thisReceiverExpression) {
-            parents += qualifiedAccessBuilder
+            parents += qualifiedAccessExpressionBuilder
             default("isImplicit", "false")
         }
 
@@ -257,11 +257,6 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
             default("contextReceiverNumber", "-1")
         }
 
-        builder(variableAssignment) {
-            parents += qualifiedAccessBuilder
-            defaultNoReceivers()
-        }
-
         builder(anonymousFunction) {
             parents += functionBuilder
             defaultNull("invocationKind", "label", "body", "controlFlowGraphReference")

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FirTreeBuilder.kt

@@ -108,7 +108,6 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val whenExpression by element(Expression, expression, resolvable)
     val whenBranch by element(Expression)
     val contextReceiverArgumentListOwner by element(Expression)
-    val qualifiedAccess by element(Expression, resolvable, statement, contextReceiverArgumentListOwner)
     val checkNotNullCall by element(Expression, expression, call, resolvable)
     val elvisExpression by element(Expression, expression, resolvable)
 
@@ -119,7 +118,7 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val errorFunction by element(Declaration, function, diagnosticHolder)
     val errorProperty by element(Declaration, variable, diagnosticHolder)
     val danglingModifierList by element(Declaration, declaration, diagnosticHolder)
-    val qualifiedAccessExpression by element(Expression, expression, qualifiedAccess)
+    val qualifiedAccessExpression by element(Expression, expression, resolvable, contextReceiverArgumentListOwner)
     val qualifiedErrorAccessExpression by element(Expression, expression, diagnosticHolder)
     val propertyAccessExpression by element(Expression, qualifiedAccessExpression)
     val functionCall by element(Expression, qualifiedAccessExpression, call)
@@ -147,8 +146,9 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val returnExpression by element(Expression, jump)
     val stringConcatenationCall by element(Expression, call, expression)
     val throwExpression by element(Expression, expression)
-    val variableAssignment by element(Expression, qualifiedAccess)
+    val variableAssignment by element(Expression, statement)
     val whenSubjectExpression by element(Expression, expression)
+    val desugaredAssignmentValueReferenceExpression by element(Expression, expression)
 
     val wrappedDelegateExpression by element(Expression, wrappedExpression)
 

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/ImplementationConfigurator.kt

@@ -354,13 +354,6 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
             publicImplementation()
         }
 
-        impl(variableAssignment) {
-            default("lValue") {
-                value = "calleeReference"
-                customSetter = "calleeReference = value"
-            }
-        }
-
         impl(anonymousFunction) {
             default("resolvePhase", "FirResolvePhase.DECLARATIONS")
         }
@@ -392,6 +385,10 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
             useTypes(whenExpression)
         }
 
+        impl(desugaredAssignmentValueReferenceExpression) {
+            useTypes(expression)
+        }
+
         impl(wrappedDelegateExpression) {
             default("typeRef") {
                 delegate = "expression"

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -205,7 +205,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +fieldList("contextReceiverArguments", expression, useMutableOrEmpty = true, withReplace = true)
         }
 
-        qualifiedAccess.configure {
+        qualifiedAccessExpression.configure {
             +typeArguments.withTransform()
             +receivers
             +field("source", sourceElementType, nullable = true, withReplace = true)
@@ -563,7 +563,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
         }
 
         checkedSafeCallSubject.configure {
-            +field("originalReceiverRef", safeCallOriginalReceiverReferenceType)
+            +field("originalReceiverRef", referenceToSimpleExpressionType)
         }
 
         callableReferenceAccess.configure {
@@ -611,8 +611,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
         }
 
         variableAssignment.configure {
-            +field("lValue", reference)
-            +field("lValueTypeRef", typeRef).withReplace()
+            +field("lValue", expression).withTransform().withReplace()
             +field("rValue", expression).withTransform()
         }
 
@@ -620,6 +619,10 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +field("whenRef", whenRefType)
         }
 
+        desugaredAssignmentValueReferenceExpression.configure {
+            +field("expressionRef", referenceToSimpleExpressionType)
+        }
+
         wrappedExpression.configure {
             +field(expression).withReplace()
         }

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt

@@ -46,7 +46,7 @@ val coneKotlinTypeType = type(ConeKotlinType::class)
 val coneSimpleKotlinTypeType = type(ConeSimpleKotlinType::class)
 
 val whenRefType = generatedType("", "FirExpressionRef<FirWhenExpression>")
-val safeCallOriginalReceiverReferenceType = generatedType("", "FirExpressionRef<FirExpression>")
+val referenceToSimpleExpressionType = generatedType("", "FirExpressionRef<FirExpression>")
 val safeCallCheckedSubjectReferenceType = generatedType("", "FirExpressionRef<FirCheckedSafeCallSubject>")
 
 val firModuleDataType = type("fir", "FirModuleData")

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/printer/element.kt

@@ -106,7 +106,8 @@ fun SmartPrinter.printElement(element: Element) {
             }
 
             allFields.filter { it.withReplace }.forEach {
-                val override = overridenFields[it, it] && !(it.name == "source" && fullQualifiedName.endsWith("FirQualifiedAccess"))
+                val override = overridenFields[it, it] &&
+                        !(it.name == "source" && fullQualifiedName.endsWith("FirQualifiedAccessExpression"))
                 it.replaceDeclaration(override, forceNullable = it.useNullableForReplace)
                 for (overridenType in it.overridenTypes) {
                     it.replaceDeclaration(true, overridenType)